TORTINI

For your delectation and delight, desultory dicta on the law of delicts.

Reference Manual’s Chapter on Expert Witness Testimony Admissibility – Part 5

March 7th, 2026

By ignoring Milward’s expert witnesses’ omissions from, and abridgements of, WOE and IBE, the appellate court blinded itself to these witnesses’ distortions of scientific method. The need for judgment, which the Milward court was keen to honor, does not mean that there are not aberrant or deviant judgments, or deviations from the standard of scientific care that are disqualifying. The need for judgment must also allow for equipoise and uncertainty that stands in the way of an inculpatory or exonerative verdict. And then there is the business of questionable research practices that subvert causal judgment. The district court had followed and acknowledged the showing of questionable research practices that pervaded Martyn Smith’s for-litigation opinions. The cheerleaders for Milward seem eager to obscure these practices by their insistence that causation is, after all, only a judgment.

The Milward decision, in its embrace of some truly aberrant methodology and judgment, and some absence of methodology, made some of its own whoopers. Martyn Smith’s incompetent analyses of the epidemiologic evidence had been thoroughly debunked in the district court, but the circuit court glibly adopted Smith’s characterizations. The appellate court failed to understand and come to grips with Smith’s rejiggering of data, and his inconsistently redefining exposures and outcomes in epidemiologic studies to make up new, fanciful results that favored his WOE-ful opinion. The appellate court also failed to understand that scientific judgment is not some vague, amorphous, unstructured decision that turns on whatever looks to be “explanatory.” Even the International Agency for Research on Cancer, which issues hazard classifications that are distorted by non-scientific precautionary principle reasoning, insists that three streams of evidence (epidemiologic, toxicologic, mechanistic) be considered separately, in accordance with criteria, with attention to the validity of each study, and synthesized into a judgment of causality following a carefully structured analysis.[1]

The appellate court in Milward took the demonstration of Smith’s failure to calculate odds ratios correctly to be something that merely went to the weight, not the admissibility, on the theory that a jury, which does not have access to the Reference Manual or to the actual studies as published, could sort it all out. And yet, when the court improvidently set out a definition of what an odds ratio is, it bungled the definition beyond understanding:

“An odds ratio represents the difference in the incidence of a disease between a population that has been exposed to benzene and one that has not.”[2]

The court’s definition is not even wrong. The difference between incidence of a disease in an exposed group and a non-exposed group is the risk difference. It is not an odds ratio. Perhaps the court might have realized what most third graders know, that there is a difference between a ratio (division) and a difference (subtraction). And of course, the odds of exposure is not the same as the incidence of a disease. The relevant odds ratio represents the odds of exposure in cases with APML diagnoses divided by the odds of exposure in study subjects without APML. The odds ratio does involve measurements of incidence although in some cases the odds ratio will approximate a risk ratio, which does involve a ratio of incidences. This is not some hyper-technicality; it is a vivid display that Chief Judge Lynch, writing for a panel of three judges of the First Circuit, had no idea of what she was reviewing or writing.

Richter and Capra devote two pages to a discussion of the Milward case and its embrace of WOE and IBE. There is not, in this discussion, a single adjective of approval or of disapproval. The attention to this one intermediate appellate court opinion far exceeds any other case decided at a level below the Supreme Court, and an engaged reader must ask why the authors of the first chapter of the new Reference Manual wrote about this case at all, especially given the 2023 amendments to Rule 702, which would suggest that Milward was bad law when decided in 2011, and clearly and emphatically bad law in December 2025, when the new Manual was published.

The chapter provides one not-so-subtle clue of the authors’ intent. At the conclusion of their extended, uncritical, and incomplete exposition of Milward,[3] Richter and Capra refer the reader to a law review symposium,[4] “[f]or a detailed analysis of the Milward decision and the weight of the evidence approach to scientific reasoning.” Like Richter and Capra’s coverage of Milward, the cited symposium was hardly an objective analysis; rather, it was more like a drunken celebration at a family reunion.

There have been many law review articles that have discussed the Milward case, but Richter and Capra chose to cite to one particular symposium, which was sponsored by two corporations, the Center for Progressive Reform (CPR) and the Robert A. Habush Foundation. The Center for Progressive Reform (CPR) is a not-for-profit corporation. Its website describes the CPR as a “research and advocacy organization that works in the service of responsive government; climate justice, mitigation, and adaptation; and protecting against environmental harm.”[5] CPR describes one of its key activities as defending science from corporate interference. Presumably its own corporate activities and those of the lawsuit industry are acceptable, but those of corporate manufacturing industry are not. From reviewing CPR’s website, it is not clear that the CPR believes manufacturing corporations should even be allowed to defend against lawsuits. Milward’s retained expert witness Carl Cranor is a “member scholar” at CPR, which makes CPR’s sponsorship of the symposium rather incestuous.[6]

CPR is also apparently comfortable with one highly politicized “corporation,” namely the American Association for Justice (AAJ), which is the trade group for the American lawsuit industry.[7] The AAJ describes itself as a corporation, or a “collective,” that supports plaintiff trial lawyers as their “collective voice … on Capitol Hill and in courthouses across the nation … .” The Robert A. Habush Foundation is endowed by the AAJ, and serves its “educational” mission.  Through the Habush Foundation, the AAJ funds educational programs, “think tanks,” and writing projects designed to influence judges, law professors, lawyers, and the public, on issues of importance to the AAJ:  “the civil justice system and individual rights” for bigger, better, and more profitable litigation outcomes. The AAJ may be a “not-for-profit” corporation, but it represents the interests of one of the most powerful, wealthiest, interest groups in American society — the plaintiffs’ bar.

The Milward symposium agenda and papers from its participants were published at the website for the Wake Forest Journal of Law and Public Policy, but now are marked as “currently private. If you would like to request access, we’ll send your username to the site owner for approval.”

The symposium cited by Richter and Capra for “analysis,” was very much a family affair. The choice of venue, at the Wake Forest Law School, was connected to the web of interests involved. CPR board member, Sid Shapiro, is a law professor at Wake Forest. Shapiro presented at the symposium, along with the Wake Forest professor Michael Green. Cranor, Shapiro’s CPR colleague, and party expert witness for plaintiff, presented.[8] There was only one practicing lawyer who presented at the symposium, Steven Baughman Jensen, who was a past chair of the AAJ’s Section on Toxic, Environmental, and Pharmaceutical Torts. Jensen represented Milward, and hired Cranor as one of the plaintiff’s expert witnesses. Attorney Jensen’s contribution to the symposium has been published along with Cranor’s as well, in the proceedings of the Milward symposium were published volume 3, no. 1 of the Wake Forest Journal of Law and Public Policy,[9] which is now also marked private. Jensen also published an abbreviated paean to Milward in in the AAJ’s trade journal.[10] No defense counsel or defense expert witness participated at the symposium, referenced by Richter and Capra.

Consistent with the financial, advocacy, and political interests of the symposium sponsors, the articles are almost all partisan high-fives for the Milward decision. Writing for the Federal Judicial Center and the National Academies, the authors of a chapter on the law of expert witnesses, a legal issue, for the Reference Manual, should have been aware of the partisan nature of the CPR-AAJ sponsored symposium. They should have flagged the advocacy nature of the symposium, and identified the funding sources and the conflicts created. Furthermore, Richter and Capra should have cited papers that criticized the Milward case, from various perspectives, including its failure to adhere to the law of Rule 702.[11] Their failure to do so is a significant failure of this chapter.


[1] IARC MONOGRAPHS ON THE IDENTIFICATION OF CARCINOGENIC HAZARDS TO HUMANS – PREAMBLE (2019).

[2] Milward, 639 F.3d at 23.

[3] Richter & Capra at 33n.96 (“For a detailed analysis of the Milward decision and the weight of the evidence approach to scientific reasoning…”).

[4] Symposium: Toxic Tort Litigation: After Milward v. Acuity Products, 3 WAKE FOREST JOURNAL OF LAW & POLICY 1 (2013).

[5] The Center for Progressive Reform, at https://progressivereform.org/, last visited on Feb. 24, 2026

[6] Carl Cranor Biography, Center for Progressive Reform, Member Scholars, at https://progressivereform.org/member-scholars/

[7] The AAJ was previously known by the more revealing name, Association of Trial Lawyers of America (ATLA®). 

[8] Carl F. Cranor, Milward v. Acuity Specialty Products: Advances in General Causation Testimony in Toxic Tort Litigation, 3 WAKE FOREST JOURNAL OF LAW & POLICY 105 (2013).

[9] Steve Baughman Jensen, Sometimes Doubt Doesn’t Sell: A Plaintiffs’ Lawyer’s Perspective on Milward v. Acuity Products, 3 WAKE FOREST JOURNAL OF LAW & POLICY 177 (2013).

[10] Steve Baughman Jensen, Reframing the Daubert Issue in Toxic Tort Cases, 49 TRIAL 46 (Feb. 2013).

[11] See Eric Lasker, Manning the Daubert Gate: A Defense Primer in Response to Milward v. Acuity Specialty Products, 79 DEF. COUNS. J. 128, 128 (2012);

David E. Bernstein, The Misbegotten Judicial Resistance to the Daubert Revolution, 89 NOTRE DAME L. REV. 27, 29, 53-58 (2013); David E. Bernstein & Eric G. Lasker, Defending Daubert: It’s Time to Amend Federal Rule of Evidence 702, 57 WM. & MARY L. REV. 1, 33 (2015); Richard Collin Mangrum, Comment on the Proposed Revision of Federal Rule 702: “Clarifying” the Court’s Gatekeeping Responsibility over Expert Testimony, 56 CREIGHTON LAW REVIEW 97, 106 & n.45 (2022); Thomas D. Schroeder, Toward a More Apparent Approach to Considering the Admission of Expert Testimony, 95 NOTRE DAME L. REV. 2039, 2045 (2020); Lawrence A. Kogan, Weight of the Evidence: A Lower Expert Evidence Standard Metastasizes in Federal Court, Washington Legal Foundation Critical Legal Issues WORKING PAPER Series no. 215 (Mar. 2020); Note, Judicial Conference Amends Rule 702. — Federal Rule of Evidence 702, 138 HARV. L. REV. 899, 903 (2025); Nathan A. Schachtman, Desultory Thoughts on Milward v. Acuity Specialty Products, DOI: 10.13140/RG.2.1.5011.5285 (Oct. 2015), available at https://www.researchgate.net/publication/282816421_Desultory_Thoughts_on_Milward_v_Acuity_Specialty_Products .

Reference Manual’s Chapter on Expert Witness Testimony Admissibility – Part 4

March 5th, 2026

In the district court, Judge George O’Toole conducted a pre-trial hearing over four days, and heard testimony from Smith and Cranor, as well as from defense expert witnesses. Judge O’Toole’s published opinion carefully and accurately stated the facts, the applicable law, and presented a well-reasoned judgment as to why Smith’s opinion was not admissible under Rule 702. Without admissible opinions on general causation to support Milward’s case, Judge O’Toole granted summary judgment to the defendants.

Milward appealed the judgment. A panel of judges in the First Circuit heard argument, and reversed in an opinion that is riddled with serious errors.[1] In reviewing the district court’s application of Rule 702, the panel, in an opinion written by Chief Judge Lynch, credulously accepted most of Smith’s and Cranor’s arguments that an ill-defined WOE approach is acceptable method of guiding scientific judgment. Cranor equated WOE, as used by Smith, to the approach that Sir Austin Bradford Hill described, in 1965, for identifying causal associations from epidemiologic data.[2] Chief Judge Lynch’s opinion tracked accurately Cranor’s and Milward’s lawyers’ misrepresentations about Sir Austin’s paper:

“Dr. Smith’s opinion was based on a ‘‘weight of the evidence’’ methodology in which he followed the guidelines articulated by world-renowned epidemiologist Sir Arthur [sic] Bradford Hill in his seminal methodological article on inferences of causality. See Arthur [sic] Bradford Hill, The Environment and Disease: Association or Causation?, 58 Proc. Royal Soc’y Med. 295 (1965).

Hill’s article explains that one should not conclude that an observed association between a disease and a feature of the environment (e.g., a chemical) is causal without first considering a variety of ‘viewpoints’ on the issue.”[3]

The quoted language from the First Circuit opinion, which twice refers to “Arthur Bradford Hill,” rather than Austin Bradford Hill, may suggest that neither Chief Judge Lynch nor his judicial colleagues and their law clerks read the classic paper. An even stronger indicator that the appellate court did not actually read this paper is evidenced in the court’s equating WOE to Bradford Hill viewpoints, without consideration of the necessary predicate for those nine viewpoints. In his short paper, Sir Austin clearly spelled out that there was a foundation needed before parsing the nine viewpoints:

“Disregarding then any such problem in semantics we have this situation. Our observations reveal an association between two variables, perfectly clear-cut and beyond what we would care to attribute to the play of chance. What aspects of that association should we especially consider before deciding that the most likely interpretation of it is causation?”[4]

Whatever Sir Arthur had to say about the matter, Sir Austin defined the starting point of causal analysis as an association free of invalidating bias and random error. The Milward decision ignored this all important predicate for assessing the various considerations that might allow for a valid association to be considered a causal association.[5] The resulting abridgement was a failure of scientific due process that distorted the Bradford Hill paper.

The First Circuit amplified its error when it asserted that from the nine considerations “no one type of evidence must be present before causality may be inferred.”[6] Although Sir Austin said something similar, one of the considerations he noted was “temporality,” in which the putative cause must come before the effect.  Most scientists would consider this consideration to be essential, unless they were observing events that were moving faster than the speed of light. The other eight considerations are more dependent upon context of the exposures and outcomes of interest, but surely strength and consistency of the clear-cut association across multiple studies is an extremely important consideration.

The First Circuit proceeds from misreading Sir Austin’s paper to misunderstanding another paper invoked by Cranor and by Milward’s lawyers. Carelessly tracking Cranor, the appellate court suggested that there was no “hierarchy of evidence”:

“For example, when a group from the National Cancer Institute was asked to rank the different types of evidence, it concluded that ‘‘[t]here should be no such hierarchy.’’ Michele Carbon [sic] et al., Modern Criteria to Establish Human Cancer Etiology, 64 Cancer Res. 5518, 5522 (2004); see also Sheldon Krimsky, The Weight of Scientific Evidence in Policy and Law, 95 Am. J. Pub. Health S129, S130 (2005).”[7]

This quoted language from the Milward opinion shows how slavishly and credulously the court adopted and regurgitated plaintiff’s argument. Sheldon Krimky was actively involved with SKAPP, and his article was presented at the SKAPP-funded Coronado Conference, discussed earlier in this series. Krimsky actually acknowledged that although “the term [WOE] is applied quite liberally in the regulatory literature, the methodology behind it is rarely explicated.”

As for the article by Carbon [sic], this publication never rejected a hierarchy of evidence. The court’s language, quoted above, follows immediately after the court’s discussion of Sir Austin’s nine types of corroborating evidence that would support the causal interpretation of an association. As such, the court seems to imply, incorrectly, that there was no hierarchy of these considerations.[8]

The court’s language also suggests that the quoted language came from the National Cancer Institute (NCI), but its provenance is quite different. The cited article’s lead author, Michele Carbone (not Carbon), was reporting on a workshop hosted by the NCI at an NCI building; it was not an official NCI event or publication. The NCI did sponsor or conduct the meeting, and Carbone’s paper was not an official statement of the NCI. Carbone’s paper was styled “Meeting Report,” and published as a paid advertisement in Cancer Research, not in the Journal of the National Cancer Institute as a scholarly article.

The discipline of epidemiology was not strongly represented at the meeting; most of the chairpersons and scientists in attendance were pathologists, cell biologists, virologists, and toxicologists. The authors of the meeting report reflect the interests and focus of the scientists in attendance. The lead author, Michele Carbone, a pathologist at the University of Hawaii, was an enthusiastic proponent of Simian Virus 40 as a cause of mesothelioma, a hypothesis that has not fared terribly well in the crucible of epidemiologic science.

The cited article did report some suggestions for modifying Bradford Hill’s criteria in the light of modern molecular biology, as well as a sense of the group that there was no “hierarchy” in which epidemiology was at the top of disciplines.  The group definitely did not address the established concept that some types of epidemiologic studies are analytically more powerful to support inferences of causality than others — the hierarchy of epidemiologic evidence. The group also did not address or reject a ranking of importance of Bradford Hill’s nine viewpoints. There was nothing remarkable about the tumor biologists’ statement that in some cases causality can be determined by careful identification of genetic inheritance or molecular biological pathways. There was no evidence of this sort in the Milward case, and the citation by Cranor and Milward’s lawyers was nothing more than hand waving.

Carbone’s meeting report summarizes informal discussion sessions at the 2003 meeting.  Those in attendance broke out into two groups, one chaired by Brook Mossman, a pathologist, and the other group chaired by Dr. Harald zur Hausen, a virologist. The meeting report included a narrative of how the two groups responded to twelve questions. Drawing from plaintiff’s (and Cranor’s) argument, the court’s citation to this meeting report is based upon one sentence in Carbone’s report, about one of twelve questions:

6. What is the hierarchy of state-of-the-art approaches needed for confirmation criteria, and which bioassays are critical for decisions: epidemiology, animal testing, cell culture, genomics, and so forth?

There should be no such hierarchy. Epidemiology, animal, tissue culture and molecular pathology should be seen as integrating evidences in the determination of human carcinogenicity.”[9]

Considering the fuller context of the meeting, there is nothing particularly surprising about this statement.  The full question and answer in the meeting report does not even remotely support the weight given to it by the court. There was quite a bit of disagreement among meeting participants over criteria for different kinds of carcinogens, as seen the report on another question:

“2. Should the criteria be the same for different agents (viruses, chemicals, physical agents, promoting agents versus initiating DNA-damaging agents)?

There were different opinions. Group 1 debated this issue and concluded that the current listing of criteria should remain the same because we lack sufficient evidence to develop a separate classification. Group 2 strongly supported the view that it is useful to separate the biological or infectious agents from chemical and physical carcinogens due to their frequently entirely different mode of action.”[10]

Carbone and the other authors of the meeting report noted the importance to epidemiology for general causation, while acknowledging its limitations for determining specific causation:

“Concerning the respective roles of epidemiology and molecular pathology, it was noted that epidemiology allows the determination of the overall effect of a given carcinogen in the human population (e.g., hepatitis B virus and hepatocellular carcinoma) but cannot prove causality in the individual tumor patient.”[11]

Clearly, the report was not disavowing the necessity for epidemiology to confirm carcinogenicity in humans. Specific causation of Mr. Milward’s APML was irrelevant to his first appeal to the First Circuit. Carbone’s report emphasized the need to integrate epidemiologic findings with molecular biology; it did not suggest that epidemiology was not necessary or urge that epidemiology be ignored or disregarded:

“A general consensus was often reached on several topics such as the need to integrate molecular pathology and epidemiology for a more accurate and rapid identification of human carcinogens.”[12]

                 * * * * *

“Ideally, before labeling an agent as a human carcinogen, it is important to have epidemiological, experimental animals, and mechanistic evidence (molecular pathology).”[13]

The court’s implication that there was “no hierarchy of evidence” is unsupported by the meeting report. The suggestion that WOE allows some loosey-goosey, ad hoc, unstructured assessment of diverse lines of evidence is rejected in the meeting report with a careful admonition about the lack of validity of some animal models and mechanistic research:

“Moreover, carcinogens and anticarcinogens can have different effects in different situations. As shown by the example of addition of β-carotene in the diet, β- carotene has chemopreventive effects in many experimental systems, yet it appears to have increased the incidence of lung cancer in heavy smokers. Animal experiments can be very useful in predicting the carcinogenicity of a given chemical. However, there are significant differences in susceptibility among species and within organs in the same species, and differences in the metabolic pathway of a given chemical among human and animals could lead to error.”[14]

Inference to the Best Explanation

The First Circuit asserted that “no serious argument can be made that the weight of the evidence approach is inherently unreliable.”[15] As discussed above, this assertion is demonstrably false. In his testimony at the Rule 702 pre-trial hearing, Cranor classified WOE as based upon “inference to the best explanation,” and the First Circuit obsequiously accepted this claim. In articulating and accepting Cranor’s reduction of scientific method to IBE, the appellate court seemed unaware that IBE as an epistemic theory has been roundly criticized. In a very general sense, IBE draws on Charles Pierce’s description of abduction as a mode of reasoning, although many writers have been eager to distinguish abduction from IBE. Bas van Fraassen criticized IBE as lacking merit as a mode of argument in a way germane to Cranor’s presentation of the notion, and the First Circuit’s uncritical acceptance:

“As long as the pattern of Inference to the Best Explanation—henceforth, IBE—is left vague, it seems to fit much rational activity. But when we scrutinize its credentials, we find it seriously wanting.”[16]

The IBE approach raises thorny problems of knowing how to discern the best explanation, or how to tell whether an explanation is simply the best of a bad lot. Other philosophers of science have questioned why explanatoriness should matter as opposed to predictive ability and resistance to falsification upon severe or robust testing.

In the hands of Smith and Cranor, these philosophical quandries become largely beside the point. For Smith and Cranor IBE becomes telling just so stories, which transform “but for” causation into “could be” causation. Drawing directly from Cranor, the Circuit Court explained that an inference to the best explanation involves six general steps for scientists:

“(1) identify an association between an exposure and a disease,

(2) consider a range of plausible explanations for the association,

(3) rank the rival explanations according to their plausibility,

(4) seek additional evidence to separate the more plausible from the less plausible explanations,

(5) consider all of the relevant available evidence, and

(6) integrate the evidence  using professional judgment to come to a conclusion about the best explanation.”[17]

Of course assessing causation requires judgment, but Cranor and Smith radically abridge the process of judging by eliminating:

  • the robust testing of, and attempts to falsify, hypotheses,
  • the weighting of study designs,
  • the pre-specification of kinds of studies to be included or excluded, the assignment of weights to different kinds and qualities of studies, and
  • the pre-specification of criteria of study validity, experimental design, consistency, and exposure-response.

The vague, contentless IBE and WOE, in the hands of Smith, operates just as van Fraassen anticipated. With Cranor’s “philosophizing,” IBE creates a permission structure to reach any desired conclusion. Indeed, Cranor’s approach makes no allowance for when careful scientists withhold judgment because the evidence is inadequate to the task. Furthermore, Cranor’s approach and the Milward decision would cheerily approve cherry picking of studies and data within studies, post hoc weighing of evidence, and even fabricating and rejiggering of evidence, all of which was on display in Smith’s for-litigation opinion.

The First Circuit uttered its mantra of approval of Smith’s scientific delicts in language that became the target of the revision of Rule 702 in 2023:

“the alleged flaws identified by the [district] court go to the weight of Dr. Smith’s opinion, not its admissibility. There is an important difference between what is unreliable support and what a trier of fact may conclude is insufficient support for an expert’s conclusion.”[18]

Earlier in its opinion, the appellate court quoted from the version of Rule 702 in effect when it heard the appeal:

“if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.”[19]

Sufficiency, reliability, and validity were all preliminary questions to be decided by the court as part of its gatekeeping responsibility.  The appellate court simply ignored the law in its decision to green light Smith’s testimony.

                    (to be continued)


[1] Milward v. Acuity Specialty Products Group, Inc., 639 F.3d 11 (1st Cir. 2011), cert. denied sub nom., U.S. Steel Corp. v. Milward, 565 U.S. 1111 (2012).

[2] Austin Bradford Hill, The Environment and Disease: Association or Causation?, 58 PROC. ROYAL SOC’Y MED. 295 (1965).

[3] Milward, 639 F.3d at 17.

[4] Id. at 295.

[5] See Frank C. Woodside, III & Allison G. Davis, The Bradford Hill Criteria: The Forgotten Predicate, 35 THOMAS JEFFERSON L. REV. 103 (2013).

[6] Milward, 639 F.3d at 17.

[7] Id. (internal citations omitted).

[8] The Reference Manual chapter on medical testimony carefully discusses the hierarchy of evidence as it factors into the assessment of medical causation. John B. Wong, Lawrence O. Gostin & Oscar A. Cabrera, Reference Guide on Medical Testimony, in National Academies of Sciences, Engineering and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 687, 723 -24 (2011); John B. Wong, Lawrence O. Gostin, & Oscar A. Cabrera, Reference Guide on Medical Testimony, in National Academies of Sciences, Engineering and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 1105, 1150-52 (4th ed. 2025). Interestingly, the chapter on epidemiology in the third edition of the Reference Manual cited to the Carbone workshop with apparent approval, but the same chapter in the fourth edition has dropped the reference. Compare Michael D. Green, D. Michal Freedman & Leon Gordis, Reference Guide on Epidemiology, in National Academies of Sciences, Engineering and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 549, 564 n.48 (3rd ed. 2011) with Steve C. Gold, Michael D. Green, Jonathan Chevrier, & Brenda Eskenazi, Reference Guide on Epidemiology, in National Academies of Sciences, Engineering and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 897 (4th ed. 2025).

[9] Carbone at 5522.

[10] Carbone at 5521.

[11] Carbone at 5518 (emphasis added).

[12] Carbone at 5518.

[13] Carbone at 5519.

[14] Carbone at 5521.

[15] Milward, 639 F.3d at 18-19.

[16] Bas van Fraassen, LAWS AND SYMMETRY 131 (1989).

[17] Milward, 639 F.3d at 18.

[18] Milward, 639 F.3d at 22.

[19] Milward, 639 F.3d at 14.

Reference Manual’s Chapter on Expert Witness Testimony Admissibility – Part 3

March 2nd, 2026

Richter and Capra treat WOE in Justice Steven’s lone dissenting opinion in Joiner as if it were the law. Of course, it was not; nor was it a particularly insightful analysis into scientific method, Rule 702, or the law of expert witnesses. The Manual authors elevate WOE by their complete failure to offer any criticisms or by citing to the scientific and legal scholars who have criticized WOE.

Richter and Capra do cite to a couple of cases that are skeptical of expert witnesses who had offered WOE opinions, but they fail to cite to any cases that disparage WOE itself.[1] In aggravation of their misplaced focus on the Joiner dissent, Richter and Capra proceed to spend two full pages on the Milward case, which had posthumously appeared in Professor Berger’s version of the law chapter in the 2011, third edition of the Reference Manual. The attention given to Milward in the fourth edition is greater than to any other non-Supreme Court case, including Frye. Richter and Capra offer no commentary or analysis critical of the case, although many legal commentators have criticized the Milward opinion on WOE.[2]

Richter and Capra’s chapter fails to note that a dark cloud hangs over the Milward case due to the unethical non-disclosure of CERT’s amicus brief filed in support of reversing the exclusion of CERT’s founders, Carl Cranor and Martyn Smith,[3] or CERT’s funding Smith’s research, or CERT’s involvement in shaking down corporations in California for Prop 65 bounties.

In their extensive coverage of the 2011 Milward decision, Richter and Capra failed to report that after the First Circuit reversed and remanded, the trial court again excluded plaintiffs’ expert witnesses for failing to give a valid opinion on specific causation. On the second appeal, the First Circuit affirmed the exclusion of specific causation expert witness testimony and the entry of final judgment for defendants.[4] Given that the first appellate decision was no longer necessary to the final disposition of the case, it is questionable whether there is any holding with respect to general causation in the case.

The most salient aspect of Richter and Capra’s uncritical coverage of the Milward case is their complete failure to identify the legal errors made by the First Circuit in its decision on Rule 702 and general causation. As the Reporter to the Rules Advisory Committee, Professor Capra was intimately involved in many meetings and memoranda that addressed the failings of courts to engage properly in gatekeeping. These failings were the gravamen of the basis for the 2023 amendments to Rule 702. The Milward decision in 2011 managed to check almost every box for bad decision making: the appellate panel ignored the text of Rule 702, disregarded Supreme Court precedent in the Joiner case, relied upon over-ruled, obsolete, pre-Daubert decisions, ignored the policy considerations urged by the Supreme Court, bungled basic scientific concepts, and egregiously and credulously endorsed WOE as advocated as a scientific methodology. Professor David E. Bernstein has pointed to the 2011 Milward decision, as “the most notorious,” and “[t]he most prominent example of such judicial truculence” in resisting following the requirements of Rule 702, as it existed in 2011.[5]

Milward is an important case, much as the Berenstain Bears stories are important and helpful in teaching children what not to do. Unfortunately, Richter and Capra discuss Milward in a way that might lead readers to believe that the case represents a reasonable or proper treatment of the science involved in the case. To correct this biased coverage of Milward, readers will have to roll up their sleeves and actually look at what the court did and did not do, and what scientific methodology issues were involved.

Perhaps the best place to begin is the beginning. Brian Milward filed a lawsuit in which he claimed that he was exposed to benzene as a refrigerator technician.[6] He developed acute promyelocytic leukeumia (APML), and claimed that he had been exposed to benzene from having used products made or sold by roughly two dozen companies. APML is a rare disease, type M3 of acute myeloid leukemia (AML), defined by specific chromosomal abnormalities that are necessary but not sufficient to result in APML. APML has an incidence of fewer than five cases per million per year. APML occurs with equal frequency in both sexes; there are no known environmental or occupational causes of APML.[7] APML occurs in the general population without benzene exposure, and its occurrence in all populations is sparse. There are no biomarkers that suggest that some putative benzene-related mechanism is involved in some APML cases, which biomarker would identify the rarity of benzene involvement in causation.

Milward’s General Causation Expert Witness, Martyn T. Smith

Milward did not serve a report from an epidemiologist, or anyone with significant expertise in epidemiology. His only general causation expert witness was Martyn Smith, a toxicologist, who testified that the “weight of the evidence” supported his opinion that benzene exposure causes APML.[8] As noted above, Smith is a member of the advocacy group, the Collegium Ramazzini; and for over 30 years, he has been a frequent testifier for plaintiffs in chemical exposure cases.[9]

Despite the low but widespread prevalence of APML in the general population, with no sex specificity, and the absence of any identifying biomarker of supposed benzene-related etiology in individual cases, Smith maintained that epidemiology was not necessary to reach a causal opinion about benzene and APML. The principal thrust of Smith’s proffered testimony is that APML is a plausible outcome of benzene exposure, because benzene can cause other varieties of AML, by structurally altering chromosomes (clastogenic) by breaking them and causing re-arrangements.[10]

The trial court found that Smith’s extrapolations were problematic and lacking in supporting evidence. The clear differences among AML subtypes made the extrapolation to APML, a unique clinical entity, inappropriate. The characteristic translocation in APML is absent from other varieties of AML, and APML, unlike other AML varieties, is treatable with all-trans retinoic acid.[11]

Smith advanced speculation that benzene targeted cells in the pathway of  leukemic transformation to APML, but the state of science was clearly devoid of sufficient evidence to show that benzene was involved in the APML translocations. Although the parties agreed that mechanistic evidence showed that benzene can effectuate chromosome damage that are characteristic of some AML subtypes other than APML, the trial court found that:

“[n]o evidence has been published making a similar connection between benzene exposure and the t(15;17) translocation, characteristic of APL [APML].”[12]

The trial court assessed Smith’s extrapolation from benzene’s clastogenic effect in breaking and rearranging chromosomes to induce some types of AML to its causing the specific APML t(15;17) translocation, as a

“bull in the china shop generalization: since the bull smashes the teacups, it must also smash the crystal. Whether that is so, of course, would depend on the bull having equal access to both teacups and crystal. If the teacups were easily knocked over, but the crystal securely stored away, a reason would exist to question, if not to reject, the proposition that the crystal was in as much danger as the teacups.”[13]

The trial judge clearly saw that Smith’s plausibility proved too much, and would support attributing virtually any disease to benzene through a putative mechanism of breaking chromosomes.

Lacking the courage of his convictions, Smith, non-epidemiologist, proceeded to offer opinions about the epidemiology of benzene and APML, some of them quite fanciful. No published or unpublished study showed a statistically significant increase in APML among benzene-exposed workers. The most Smith could draw from the published epidemiologic studies on benzene was one Chinese study that found a small risk ratio, without even nominal statistical significance: a crude odds ratio of 1.42 for benzene exposure and APML. Despite Smith’s hand waving about lack of power,[14] this Chinese study suggested that chloramphenicol was a risk factor for APML (M3), and it was able to identify a nominally statistically significant association between benzene and another sub-type of AML (M2a), with an odds ratio of 1.54.[15]

Smith offered no meta-analysis to show that the available studies collectively established a summary estimate of increased risk for APML among benzene workers. Undaunted, Smith set about to re-jigger the numbers in published studies to make something out of nothing. Neither physician nor epidemiologist, Smith altered diagnoses and exposure status as reported in published papers so that his reclassified cases and controls would yield, where none existed. These re-analyses were done speculatively, inconsistently, and incompetently, and were driven by the motivation to make something out of nothing. His approach was unsupported, unprincipled, and lacking in any reasonable methodology. The proffered re-analyses were never published, never presented at a professional society meeting, and never could comply with the standards used by epidemiologists used in their non-litigation activities. As a toxicologist, Smith did not have any non-litigation epidemiologic activities of note.

Smith’s representation of the relevant epidemiologic methods and studies was misleading and contained numerous errors that cumulatively led to erroneous conclusions; his own re-jiggering was carried out to reach a preferred conclusion to support plaintiff’s litigation case.[16]

One of the epidemiologic studies relied upon by Smith was Golumb (1982).[17] This study did not explore associations with benzene; it was a study of insecticides, chemicals and solvents, and petroleum. Crude oil contains very little benzene, typically about 0.1 percent.[18] Smith, without any evidentiary support, assumed that petroleum exposure equated to benzene exposure.

There were eight cases of cases of leukemia with petroleum exposure; one of those cases was APML. The authors of Golumb (1982) reported that this particular case with APML was actually a crane operator.[19]

In analyzing published epidemiologic studies, Smith insisted that he could re-classify APML cases to non-APML in control subjects, in studies, when the karyotype was normal. Karyotype analysis identifies the defining translocations of specific chromosomes in APML, and is found in virtually all such cases. The obvious result of Smith’s ad hoc reclassifications were to increase risk ratios for APML among benzene-exposed subjects. His arbitrary reclassifications of data allowed him to create the result he desired. In reviewing other published studies, Smith insisted that normal karyotype did not require reclassifying cases out of the APML category, when this approach would yield a risk ratio above one. 

Taking data from the Golumb 1982 paper, Smith attempted to inflate his calculation of an odds ratio, which would support his causation opinion. He arbitrarily discarded two APML from the non-exposed cases, and he discarded eight non-APML cases from the exposed subjects. He did not report p-values or confidence intervals for his reanalyses. At the hearing, the defense epidemiologist showed that Smith’s rejiggered odds ratio (1.51) had a p-value of 0.72, and a 95 percent confidence interval of 0.15 – 14.91. Not only was the result not statistically significant, the confidence interval shows that there was a range of alternative hypotheses over an order of magnitude in range, with none of them being rejected based upon the sample data at an alpha of 0.05. Without the rejiggering of exposed and unexposed cases, the odds ratio would have been 0.71, p = 0.76. All results, both as reported in the published article and as rejiggered by Smith were highly compatible with no association whatsoever.

In discussing other studies, Smith repeated his re-labeling of leukemia cases as APML, in the absence of karyotyping, to support his claims that there were more APML cases observed than expect on general population rates.[20] Smith also cited studies improvidently in supposed support of his opinion (Rinsky 1981; updated in 1994), where there was no association at all. Even workers heavily exposed to benzene in these studies did not develop APML.[21]  Similarly, in support of his opinion, Smith cited another Chinese study, which actually declared that:

“Acute promyelocytic leukemia has been reported infrequently in benzene-exposed groups as well as in t-ANLL. Although ANLL-M3 occurred in at least 4 patients in this series, its general representation among the subtypes of ANLL was similar in its distribution in de novo ANLL in China.”[22]

Smith’s methodological improprieties were the subject of a four day pre-trial hearing before Judge O’Toole. In the course of the hearings, Smith attempted to defends his methods, but like Donny Kerabatsos, in the Big Lebowski, Smith was out of his depth. The trial court found that Dr. Smith’s arbitrary creating and choosing data to support his beliefs was unreliable and not in accordance with generally accepted scientific methodology in the fields of medicine or epidemiology. Smith was simply fabricating data to fit his made-for-litigation beliefs.

Carl Cranor’s Attempt to Bolster Smith

Milward also submitted a report from Carl Forest Cranor, Smith’s business partner in founding the Prop 65 bounty-hunting CERT, and a fellow member of the advocacy group Collegium Ramazzini. Cranor has no expertise in toxicology or epidemiology, and he has never published on the cause of APML. As a professor of philosophy, Cranor has written about scientific methodology, including WOE and “inference to the best explanation (IBE).” Cranor’s publications are riddled with basic misunderstandings of statistical concepts.[23] Essentially, Cranor testified at the Rule 702 hearing, as a cheerleader for Smith, and to advocate for open admissions of dodgy scientific conclusions as acceptable with a methodology he described as WOE or IBE. Cranor stretched to resurrect Justice Stevens’ use of WOE, and attempted to pass it off as a generally accepted scientific mode of reasoning.

The trial court carefully reviewed the proffered opinion testimony in a four day pre-trial hearing. The trial court found that Smith had shown that his hypothesis was plausible and possible, but not that it was “scientific knowledge,” as required by Rule 702. Lacking sufficient scientific methodological validity and support, Smith’s opinions failed to satisfy the requirements of Rule 702, and were thus inadmissible. As a result of excluding plaintiff’s sole general causation expert witness, the trial court granted summary judgment to the defendants.[24]

(to be continued)


[1] See, e.g., Allen v. Pennsylvania Eng’g Corp., 102 F.3d 194, 197-98 (5th Cir. 1996) (“We are also unpersuaded that the ‘weight of the evidence’ methodology these experts use is scientifically acceptable for demonstrating a medical link between Allen’s EtO [ethylene oxide] exposure and brain cancer.”); Magistrini v. One Hour Martinizing Dry Cleaning, 180 F. Supp. 2d 584, 601-02 (D.N.J. 2002) (excluding David Ozonoff, whose WOE analysis of whether perchloroethylene causes acute myelomonocytic leukemia was criticized by court-appointed technical advisor), aff’d, 68 F. App’x 356 (3d Cir. 2003).

[2] See Eric Lasker, Manning the Daubert Gate: A Defense Primer in Response to Milward v. Acuity Specialty Products, 79 DEF. COUNS. J. 128, 128 (2012); David E. Bernstein, The Misbegotten Judicial Resistance to the Daubert Revolution, 89 NOTRE DAME L. REV. 27, 29, 53-58 (2013); David E. Bernstein & Eric G. Lasker, Defending Daubert: It’s Time to Amend Federal Rule of Evidence 702, 57 WM. & MARY L. REV. 1, 33 (2015); Richard Collin Mangrum, Comment on the Proposed Revision of Federal Rule 702: “Clarifying” the Court’s Gatekeeping Responsibility over Expert Testimony, 56 CREIGHTON LAW REVIEW 97, 106 & n.45 (2022); Thomas D. Schroeder, Toward a More Apparent Approach to Considering the Admission of Expert Testimony, 95 NOTRE DAME L. REV. 2039, 2045 (2020); Lawrence A. Kogan, Weight of the Evidence: A Lower Expert Evidence Standard Metastasizes in Federal Court, Washington Legal Foundation Critical Legal Issues WORKING PAPER Series no. 215 (Mar. 2020); Note, Judicial Conference Amends Rule 702. — Federal Rule of Evidence 702, 138 HARV. L. REV. 899, 903 (2025); Nathan A. Schachtman, Desultory Thoughts on Milward v. Acuity Specialty Products, DOI: 10.13140/RG.2.1.5011.5285 (Oct. 2015), available at https://www.researchgate.net/publication/282816421_Desultory_Thoughts_on_Milward_v_Acuity_Specialty_Products .

[3] See David DeMatteo & Kellie Wiltsie, When Amicus Curiae Briefs are Inimicus Curiae Briefs: Amicus Curiae Briefs and the Bypassing of Admissibility Standards, 72 AM. UNIV. L. REV. 1871 (2022) (noting that amicus briefs often include “unvetted and potentially inaccurate, misleading, or mischaracterized expert information,” without the procedural safeguards in place for vetting expert witnesses at trial).

[4] Milward v. Acuity Specialty Prods. Group, Inc., 969 F. Supp. 2d 101, 109 (D. Mass. 2013), aff’d sub. nom., Milward v. Rust-Oleum Corp., 820 F.3d 469, 471, 477 (1st Cir. 2016).

[5] David E. Bernstein, The Misbegotten Judicial Resistance to the Daubert Revolution, 89 NOTRE DAME L. REV. 27, 53, 29 (2013).

[6] Milward v. Acuity Specialty Products Group, Inc., 664 F. Supp. 2d 137 (D. Mass. 2009) (O’Toole, J.), rev’d, 639 F.3d 11 (1st Cir. 2011), cert. denied, U.S. Steel Corp. v. Milward, 565 U.S. 1111 (2012).

[7] Andrew Y. Li, et al., Clustered incidence of adult acute promyelocytic leukemia in the vicinity of Baltimore, 61 LEUKEMIA & LYMPHOMA 2743 (2021); Hassan Ali, et al., Epidemiology and Survival Outcomes of Acute Promyelocytic Leukemia in Adults: A SEER Database Analysis, 144 BLOOD 5942 S1 (2024).

[8] Milward, 664 F. Supp. 2d at 142.

[9] See, e.g., PPG Industries, Inc. v. Wells, No. 21-0232 (Feb. 10, 2023 W.Va.S.Ct.); Hall v. ConocoPhillips, 248 F. Supp. 3d 1177 (W.D. Okla. 2017); In re Levaquin Prods. Liab. Litig., 739 F.3d 401 (8th Cir. 2014); Jacoby v. Rite Aid Corp., No. 1508 EDA 2012 (Dec. 9, 2013 Pa. Super.); Harris v. CSX Transp., Inc., 232 W.Va. 617, 753 S.E.2d 275 (2013); In re Baycol Prods. Litig., 495 F. Supp. 2d 977 (D. Minn. 2007); In re Rezulin Prods. Liab. Litig., MDL 1348, 441 F.Supp.2d 567 (S.D.N.Y. 2006) (advocating mythological “silent injury”); Perry v. Novartis, 564 F.Supp.2d 452 (E.D. Pa. 2008); Dodge v. Cotter Corp., 328 F.3d 1212 (10th Cir. 2003); Sutera v. The Perrier Group of America Inc., 986 F. Supp. 655 (D. Mass. 1997); Redland Soccer Club, Inc. v. Dep’t of Army, 835 F.Supp. 803 (M.D. Pa. 1993).

[10] Milward, 664 F.Supp. 2d at 143-44.

[11] Milward, 664 F.Supp. 2d at 144.

[12] Id. at 146

[13] Id.

[14] The claim that a study lacks power is meaningless without a specification of the alternative hypothesis, the risk ratio the researcher thinks is the population parameter, at a specified level of alpha (typically p < 0.05), and a specified probability model. While virtually all studies would have reasonable statistical power (say 80 percent probability) to reject an alternative hypothesis that the risk ratio exceeded 10,000, no study would have power to detect a risk ratio of 1.0001, at a high level of probability.

[15] Yi Zhongguo, et al. (National Investigative Group for the Survey of Leukemia & Aplastic Anemia), Countrywide Analysis of Risk Factors for Leukemia and Aplastic Anemia, 14 ACTA ACADEMIAE MEDICINAE SINICAE 185 (1992).

[16] Milward, 664 F. Supp. 2d at 148-49.

[17] Harvey M. Golomb, et al., Correlation of Occupation and Karyotype in Adults With Acute Nonlymphocytic Leukemia, 60 BLOOD 404 (1982).

[18] Bo Holmberg, Per Lundberg, Benzene: standards, occurrence, and exposure, 7 AM. J. INDUS. MED. 375 (1985).

[19] Golumb, supra at note 17, at 407.

[20] See, e.g., Song-Nian Yin, et al., A cohort study of cancer among benzene-exposed workers in China: overall results, 29 AM. J. INDUS. MED. 227 (1996).

[21] Robert A. Rinsky, et al., Leukemia in Benzene Workers, 2 AM. J. INDUS. MED. 217 (1981); Mary B. Paxton, et al., Leukemia Risk Associated with Benzene Exposure in the Pliofilm Cohort: I. Mortality Update and Exposure Distribution, 14 RISK ANALYSIS 147 (1994); Mary B. Paxton, et al., Leukemia Risk Associated with Benzene Exposure in the Pliofilm Cohort II. Risk Estimates, 14 RISK ANALYSIS 155 (1994).

[22] Lois B. Travis, et al., Hematopoietic Malignancies and Related Disorders Among Benzene-Exposed Workers in China, 14 LEUKEMIA & LYMPHOMA 91, 99 (1994).

[23] See, e.g., Carl F. Cranor, REGULATING TOXIC SUBSTANCES: A PHILOSOPHY OF SCIENCE AND THE LAW at 33-34(1993) (conflating random error with posterior probabilities: “One can think of α, β (the chances of type I and type II errors, respectively) and 1- β as measures of the “risk of error” or “standards of proof.”); id. at 44, 47, 55, 72-76.

[24] 664 F. Supp. 2d at 140, 149.

The Fourth Edition’s Chapter on Admissibility of Expert Witness Testimony – Part 2

February 24th, 2026

The Manual’s new law chapter on the admissibility (vel non) of expert witness testimony was written by two law professors who teach evidence, and who often write articles with each another.[1] Liesa Richter teaches at the University of Oklahoma College of Law. Daniel Capra teaches at Fordham School of Law, in Manhattan. For the last three decades, Capra has been the Reporter for the Judicial Conference Advisory Committee on the Federal Rules of Evidence. There probably is no evidence law scholar more involved with the Federal Rules, including with the key expert witness rules, Rule 702 and Rule 703, than Capra.

The new chapter’s strengths follow from Professor Capra’s involvement in the evolution of Rule 702. The chapter plainly acknowledges that the Supreme Court decisions in the 1990s follow from an epistemic standard, and the use of the terms “scientific” and “knowledge” in Rule 702. Counting heads, as suggested by the Frye case, was at times a weak and ambiguous proxy for knowledge.[2] The new chapter has the important advantage of not having authors entwined in the advocacy of dodgy groups such as SKAPP, and the Collegium Ramazzini. Gone from the new chapter are Berger’s gratuitous and unwarranted endorsements and mischaracterizations of carcinogenicity evaluations by the International Agency for Research on Cancer (IARC).

Like Berger’s previous versions of this chapter, the new chapter carefully explains the Supreme Court decisions on expert witness admissibility and the changes in Rule 702, over time, including the 2023 amendment to 702. One glaring omission from the new chapter is absence of any mention of the fourth Supreme Court case in the 1993-2000 quartert: Weisgram v. Marley.[3] This important opinion by Justice Ginsburg was a clear expression of the seriousness with which the Court took the gatekeeping enterprise:

“Since Daubert, moreover, parties relying on expert testimony have had notice of the exacting standards of reliability such evidence must meet… . It is implausible to suggest, post-Daubert, that parties will initially present less than their best expert evidence in the expectation of a second chance should their first trial fail.”[4]

Professor Berger discussed this case in her last chapter, but the new authors fail to mention it all.[5] 

On the plus side, Richter and Capra discuss, although way too briefly, the role that Federal Rule of Evidence 703 plays in governing expert witness testimony.[6]  Rule 703 does not address the admissibility of expert witnesses’ opinions, but it does give trial courts control over what hearsay facts and data (such as published studies), otherwise inadmissible, upon which expert witnesses can rely.[7] Richter and Capra do not, however come to grips what how Rule 703 will often require trial courts to engage with the specifics of the validity and flaws of specific studies in order to evaluate the reasonableness of expert witness reliance upon them. Berger, in the third edition of the Manual, completely failed to address Rule 703, and its important role in gatekeeping.

Richter and Capra helpfully advise judges to be cautious in relying upon pre-2023 amendment cases because that most recent amendment was designed to correct clearly erroneous applications of Rule 702 in both federal trial and appellate courts.[8] The new Manual authors also deserve credit for being willing to call out judges for ignoring the Rule 702 sufficiency prong and for invoking the evasive dodge of many courts in characterizing expert witness challenges as going to “weight not admissibility.”[9]

Richter and Capra improve upon past chapters by simply reporting that the 2023 amendment to Rule 702 addressed important concerns that courts were failing to keep expert witnesses “within the bounds of what can be concluded from a reliable application of the expert’s basis and methodology,” and that Rule Rule 702(d) was amended to emphasize their legal obligation to do so.[10] Berger could have discussed this phenomenon even back in 2010-11, but failed to do so.

The new authors report that the Rules Advisory Committee had been concerned that expert witnesses engage regularly in overstating or overclaiming the appropriate level of certainty for their opinions, especially in the context of forensic science.[11] Although the recognition of problematic overclaiming in forensic science is a welcomed development, Richter and Capra fail to recognize that overclaiming is at the heart of the Milward case involving benzene exposure and acute promyelocytic leukemia (APL). And they seem unaware that overclaiming is baked into the precautionary principle that drives IARC pronouncements, advocacy positions of groups such as the Collegium Ramazzini, and much of regulatory rule-making.

In several respects, Richter and Capra have improved upon the past three editions in presenting the law of expert witness testimony. The new chapter gives a brief exposition of the Joiner case,[12] where the Court concluded that that there was an “analytical gap” between the plaintiffs’ experts witnesses’ conclusion on causation and the animal and human studies upon which they relied. The authors’ summary of the case explains that the Supreme Court majority concluded that the trial court below was well within its discretion to find that the plaintiffs’ expert witnesses had a cavernous analytical gap between their relied upon evidence and their conclusion that polychlorobiphenyls (PCBs) caused Mr. Joiner’s lung cancer.

Richter and Capra’s goes sideways in addressing the dissent by Justice Stevens and by giving it uncritical, disproportionate attention. As a dissent, which has never gained any serious acceptance on the high court by any other member, Justice Stevens’ opinion in Joiner hardly deserved any mention at all. Richter and Capra note, however, early in the chapter that Justice Stevens’ criticized the majority in Joiner for having “examined each study relied upon by the plaintiff’s experts in a piecemeal fashion and concluded that the experts’ opinions on causation were unreliable because no one study supported causation.”[13] Stevens’ criticism was wide of the mark in that the Court specifically addressed the “mosaic” theory that was a reprise of the plaintiffs’ unsuccessful strategy in the Bendectin litigation.[14]

Justice Stevens’ dissent wantonly embraced Joiner’s expert witnesses’ use of a “weight of the evidence” (WOE) methodology. Stevens asserted that WOE is accepted in regulatory circles, which is true but irrelevant, and that it is accepted in scientific circles, which is a gross exaggeration and misrepresentation. Richter and Capra somehow manage to discuss Stevens’ WOE argument twice,[15] thereby giving undue, uncritical emphasis and appearing to endorse it over the majority opinion, which after all contained the holding of the Joiner case. The authors give credence to the WOE argument in Joiner by suggesting that the majority had not adequately addressed it, and by failing to provide or cite any critical commentary on WOE.

Careful readers will be left wondering why their time is being wasted with the emphasis on a dissent that was never the law, that mischaracterized the majority opinion, that endorsed a method, WOE, that has been widely criticized, and that never persuaded any other justice to join.

The scientific community has never been seriously impressed by the so-called WOE approach to determining causality.  The phrase is vague and ambiguous; its use, inconsistent.[16] Although the phrase, WOE, is thrown around a lot, especially in regulatory contexts, it has no clear, consistent meaning or mode of application.[17]

Many lawyers, like Justice Stevens, Richter, and Capra, may feel comfortable with WOE because the phrase is used often in the law, where the subjectivity, vagueness, lack of structure and hierarchy to the metaphor “weighing” evidence is seen as a virtue that avoids having to worry too much about the evidential soundness of verdicts.[18] The process of science, however, is not like that of a jury’s determination of a fact such as who had the right of way in a car collision case. Not all evidence is the same in science, and a scientific judgment is not acceptable when it hangs on weak evidence and invalid inferences.

The lawsuit industry and its expert witnesses have adopted WOE, much as they have the equally vague term, “link,” for WOE’s permissiveness of causal inferences. WOE frees them from the requirement of any meaningful methodology, which means that any conclusion is possible, including their preferred conclusion. Under WOE, any conclusion can survive gatekeeping as an opinion. WOE frees the putative expert witness from the need to consider the quality of research. WOE-ful enthusiasts such as Carl Cranor invoke WOE or seek to inflict WOE without mentioning the crucial “nuts and bolts” of scientific inference, such as concepts of

  • Internal and external validity
  • A hierarchy of evidence
  • Assessment of random error
  • Assessment of known and residual confounding
  • Known and potential threats to validity
  • Pre-specification of end points and statistical analyses
  • Pre-specification of weights to be assigned, and inclusionary and exclusionary criteria for studies
  • Appropriate synthesis across studies, such as systematic review and meta-analysis

These important concepts are lost in the miasma of WOE.

If Richter and Capra wished to take a deeper dive into the Joiner case, rather than elevate the rank speculation of the lone dissenter, Justice Stevens, they may have asked whether Joiner’s expert witnesses relied upon all, or the most carefully conducted, epidemiologic studies.

As the record was fashioned, the Supreme Court’s discussion of the plaintiffs’ expert witnesses’ methodological excesses and failures did not include a discussion of why the excluded witnesses had failed to rely upon all the available epidemiology. The challenged witnesses relied upon an unpublished Monsanto study, but apparently ignored an unpublished investigation by NIOSH government researchers, who found that there were “no excess deaths from cancers of the … the lung,” among PCB-exposed workers at a Westinghouse Electric manufacturing facility. Actually, the NIOSH report indicated a statistically non-significant decrease in lung cancer rate among PCB exposed workers, with fairly a narrow confidence interval; SMR = 0.7 (95% CI, 0.4 – 1.2).[19] By the time the Joiner case was litigated, this unpublished NIOSH report was published and unjustifiably ignored by Joiner’s expert witnesses.[20] Twenty years after Joiner was decided in the Supreme Court, NIOSH scientists published updated data from this cohort, which showed that the long-term lung cancer mortality for PCB-exposed workers remained reduced, with a standardized mortality ratio of 0.88 (95% C.I., 0.7–1.1) for the cohort, and even lower for the workers with the highest levels of exposure, 0.82 (95% C.I., 0.5–1.3).[21]

At the time the Joiner case was on its way up to the Supreme Court, two Swedish studies were available, but they were perhaps too small to add much to the mix of evidence.[22] Another North American study published in 1987, and not cited by Joiner’s expert witnesses, was also conducted in a cohort of North American PCB-exposed capacitor workers, and showed less than expected mortality from lung cancer.[23] Joiner thus represents not only an analytical gap case, but also a cherry picking case. The Supreme Court was eminently correct to affirm the shoddy evidence proffered in the Joiner case.

Thirty years after the Supreme Court decided Joiner, the claim that PCBs cause lung cancer in humans remains unsubstantiated. Subsequent studies bore out the point that Joiner’s expert witnesses were using an improper, unsafe methodology and invalid inferences to advance a specious claim.[24] In 2015, researchers published a large, updated cohort study, funded by General Electric, on the mortality experience of workers in a plant that manufactured capacitors with PCBs. The study design was much stronger than anything relied upon by Joiner’s expert witnesses, and its results are consistent with the NIOSH study available to, but ignored by, them. The results are not uniformly good for General Electric, but on the end point of lung cancer for men, the standardized mortality ratio was 81 (95% C.I., 68 – 96), nominally statistically significantly below the expected SMR of 100.[25]

There is also the legal aftermath of Joiner, in which the Supreme Court reversed and remanded the case to the 11th Circuit, which in turn remanded the case back to the district court to address claims that Mr. Joiner had also been exposed to furans and dioxins, and that these other chemicals had caused, or contributed to, his lung cancer, as well.[26] 

Thus the dioxins were left in the case even after the Supreme Court ruled on admissibility of expert witnesses’ opinions on PCBs and lung cancer. Anthony Roisman, a lawyer with the plaintiff-side National Legal Scholars Law Firm, P.C., argued that the Court had addressed an artificial question when asked about PCBs alone because the case was really about an alleged mixture of exposures, and he held out hope that the Joiners would do better on remand.[27]

Alas, the Joiner case evaporated in the district court. In February 1998, Judge Orinda Evans, who had been the original trial judge, and who had sustained defendants’ Rule 702 challenges and granted their motions for summary judgments, received and reopened the case upon remand from the 11th Circuit. Judge Evans set a deadline for a pre-trial order, and then extended the deadline at plaintiff’s request. After Joiner’s lawyers withdrew, and then their replacements withdrew, the parties ultimately stipulated to the dismissal of the case with prejudice, in February 1999. The case had run its course, and so had the claim that dioxins were responsible for plaintiff’s lung cancer.

In 2006, the National Research Council published a monograph on dioxin, which took the controversial approach of focusing on all cancer mortality rather than specific cancers that had been suggested as likely outcomes of interest.[28] The validity of this approach, and the committee’s conclusions, were challenged vigorously in subsequent publications.[29] In 2013, the Industrial Injuries Advisory Council (IIAC), an independent scientific advisory body in the United Kingdom, published a review of lung cancer and dioxin. The Council found the epidemiologic studies mixed, and declined to endorse the compensability of lung cancer for dioxin-exposed industrial workers.[30]

In 1996, when Justice Stevens dissented in Joiner, and over the course of three decades, Stevens’ assessment of science, scientific methodology, and law have been wrong. His viewpoints never gained acceptance from any other justice on the Supreme Court. Richter and Capra, in writing the first chapter of the new Reference Manual, lead judges and lawyers astray in improvidently elevating the dissent, as though it were law, and in failing to provide sufficient context, analysis, and criticism.

(To be continued.)


[1] Liesa L. Richter & Daniel J. Capra, The Admissibility of Expert Testimony, National Academies of Sciences, Engineering, and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 1 (4th ed. 2025).

[2] Id. at 6.

[3] 528 U.S. 440 (2000).

[4] 528 U.S. at 445 (internal citations omitted).

[5] Margaret A. Berger, The Admissibility of Expert Testimony, in National Academies of Sciences, Engineering and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 11, 18-19 (3rd 2011).

[6] Richter & Capra at 17.

[7] See Nathan A. Schachtman, Rule of Evidence 703—Problem Child of Article VII, PROOF 3 (Spring 2009).

[8] Id. at 13.

[9] Id. at 16.

[10] Id. at 22-23.

[11] Id. at 23, 39.

[12] General Electric Co. v. Joiner, 522 U.S. 136 (1997).

[13] Richter & Capra at 10 (citing General Electric Co. v. Joiner, 522 U.S. 136, 150-155 (1997) (Stevens, J.).

[14] Joiner, 522 U.S. at 147-48.

[15] Richter & Capra at 10, 31.

[16] See, e.g., V. H. Dale, G.R. Biddinger, M.C. Newman, J.T. Oris, G.W. Suter II, T. Thompson, et al., Enhancing the ecological risk assessment process, 4 INTEGRATED ENVT’L ASSESS. MANAGEMENT 306 (2008) (“An approach to interpreting lines of evidence and weight of evidence is critically needed for complex assessments, and it would be useful to develop case studies and/or standards of practice for interpreting lines of evidence.”); Igor Linkov, Drew Loney, Susan M. Cormier, F.Kyle Satterstrom & Todd Bridges, Weight-of-evidence evaluation in environmental assessment: review of qualitative and quantitative approaches, 407 SCI. TOTAL ENV’T 5199–205 (2009); Douglas L. Weed, Weight of Evidence: A Review of Concept and Methods, 25 RISK ANALYSIS 1545 (2005) (noting the vague, ambiguous, indefinite nature of the concept of WOE review); R.G. Stahl Jr., Issues addressed and unaddressed in EPA’s ecological risk guidelines, 17 RISK POLICY REPORT 35 (1998); (noting that U.S. EPA’s guidelines for ecological WOE approaches to risk assessment fail to provide meaningful guidance); Glenn W. Suter & Susan M. Cormier, Why and how to combine evidence in environmental assessments: Weighing evidence and building cases, 409 SCI. TOTAL ENV’T 1406, 1406 (2011) (noting arbitrariness and subjectivity of WOE “methodology”).

[17] See Charles Menzie, et al., “A weight-of-evidence approach for evaluating ecological risks; report of the Massachusetts Weight-of-Evidence Work Group,” 2 HUMAN ECOL. RISK ASSESS. 277, 279 (1996)  (“although the term ‘weight of evidence’ is used frequently in ecological risk assessment, there is no consensus on its definition or how it should be applied”); Sheldon Krimsky, “The weight of scientific evidence in policy and law,” 95 AM. J. PUB. HEALTH S129 (2005) (“However, the term [WOE] is applied quite liberally in the regulatory literature, the methodology behind it is rarely explicated.”).

[18] See, e.g., People v. Collier, 146 A.D.3d 1146, 1147-48, 2017 NY Slip Op 00342 (N.Y. App. Div. 3d Dep’t, Jan. 19, 2017) (rejecting appeal based upon defendant’s claim that conviction was against “weight of the evidence”); Venson v. Altamirano, 749 F.3d 641, 656 (7th Cir. 2014) (noting “new trial is appropriate if the jury’s verdict is against the manifest weight of the evidence”).

[19] Thomas Sinks, et al., Health Hazard Evaluation Report, HETA 89-116-209 (Jan. 1991).

[20] Thomas Sinks, et al., Mortality among workers exposed to polychlorinated biphenyls,” 136 AM. J. EPIDEMIOL. 389 (1992).

[21] Avima M. Ruder, et al., Mortality among Workers Exposed to Polychlorinated Biphenyls (PCBs) in an Electrical Capacitor Manufacturing Plant in Indiana: An Update, 114 ENVT’L HEALTH PERSP. 18, 21 (2006).

[22] P. Gustavsson, et al., Short-term mortality and cancer incidence in capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs), 10 AM. J. INDUS. MED. 341 (1986); P. Gustavsson & C. Hogstedt, “A cohort study of Swedish capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs),” 32 AM. J. INDUS. MED. 234 (1997) (cancer incidence for entire cohort, SIR = 86, 95%; CI 51-137).

[23] David P. Brown, “Mortality of workers exposed to polychlorinated biphenyls–an update,” 42 ARCH. ENVT’L HEALTH 333, 336 (1987

[24] See Mary M. Prince, et al., Mortality and exposure response among 14,458 electrical capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs), 114 ENVT’L HEALTH PERSP. 1508, 1511 (2006) (reporting a nominally statistically significant decreased mortality ratio of 0.78, 95% C.I. 0.65–0.93, for men exposed to PCBs); Avima M. Ruder, Mortality among 24,865 workers exposed to polychlorinated biphenyls (PCBs) in three electrical capacitor manufacturing plants: a ten-year update, 217 INT’L J. HYG. & ENVT’L HEALTH 176, 181 (2014) (reporting no increase in the lung cancer standardized mortality ratio for long-term workers, 0.99, 95% C.I., 0.91–1.07).

[25] Renate D. Kimbrough, et al., Mortality among capacitor workers exposed to polychlorinated biphenyls (PCBs), a long-term update, 88 INT’L ARCH. OCCUP. & ENVT’L HEALTH 85 (2015).

[26] Joiner v. General Electric Co., 134 F.3d 1457 (11th Cir. 1998) (per curiam).

[27] Anthony Z. Roisman, The Implications of G.E. v. Joiner for Admissibility of Expert Testimony, 65 VT. J. ENVT’L L. 1 (1998).

[28] See David L. Eaton (Chairperson), HEALTH RISKS FROM DIOXIN AND RELATED COMPOUNDS – EVALUATION OF THE EPA REASSESSMENT (2006).

[29] Paolo Boffetta, et al., TCDD and cancer: A critical review of epidemiologic studies,” 41 CRIT. REV. TOXICOL. 622 (2011) (“In conclusion, recent epidemiological evidence falls far short of conclusively demonstrating a causal link between TCDD exposure and cancer risk in humans.”).

[30] Industrial Injuries Advisory Council – Information Note on Lung cancer and Dioxin (December 2013). See also Mann v. CSX Transp., Inc., 2009 WL 3766056, 2009 U.S. Dist. LEXIS 106433 (N.D. Ohio 2009) (Polster, J.) (dioxin exposure case) (“Plaintiffs’ medical expert, Dr. James Kornberg, has opined that numerous organizations have classified dioxins as a known human carcinogen. However, it is not appropriate for one set of experts to bring the conclusions of another set of experts into the courtroom and then testify merely that they ‘agree’ with that conclusion.”), citing Thorndike v. DaimlerChrysler Corp., 266 F. Supp. 2d 172 (D. Me. 2003) (court excluded expert who was “parroting” other experts’ conclusions).

The Reference Manual’s Chapter on Expert Witness Testimony Admissibility – Part One

February 23rd, 2026

With the retraction of the climate science chapter, The Reference Manual on Scientific Evidence is now one chapter shorter, at least in the Federal Judicial Center’s version. At the time of this writing, for curious souls, the National Academies version is still sporting the climate advocacy chapter. Even without the climate chapter, the Manual is over 1,000 pages, and more than a casual weekend read. Many judges, finding this tome on their desks, will read individual subject matter chapters pro re nata. The first chapter in the Manual, however, is about the law, not science, and might be the starting place for the ordinary work-a-day judge. As in past editions of the Manual, the new edition has a chapter on the The Admissibility of Expert Testimony. In the first, second, and third editions, this chapter was written by Professor Margaret Berger. In the fourth edition, the chapter on the law was written by law professors Liesa Richter and Daniel Capra. To understand and evaluate the most recent iteration, the reader should have some sense of what has gone before.

Previous Chapters on Admissibility of Expert Witness Testimony

Professor Berger’s past chapters had been idiosyncratic productions.[1] Berger was an evidence law scholar, who wrote often about expert witness admissibility issues.[2] She was also known for her antic proposals, such as calling for abandoning the element of causation in products liability cases.[3] As an outspoken ideological opponent of expert witness gatekeeping, Berger was a strange choice to write the law chapter of the Manual.[4] Berger’s chapters in the first through the third editions made her opposition to gatekeeping obvious, and this hostility may have been responsible for some of the judicial resistance to applying the clear language of Rule 702, even after its 2000 revision.

Berger was not only a law professor; she was at the center of ideological and financially conflicted groups that worked to undermine the application of Rule 702 in health effects cases. One of the key players in this concerted action was David Michaels. Currently, Michaels teaches epidemiology at the George Washington University Milken Institute School of Public Health. He is a card-carrying member of the Collegium Ramazzini, an organization that has participated in efforts to corrupt state and federal judges by funding ex parte conferences with lawsuit industry expert witnesses.[5] Michaels is the author of two books, both highly anti-manufacturing industry, and biased in favor of the lawsuit industry.[6] Both books are provocatively titled anti-industry diatribes, which have little scholarly value, but are used regularly by plaintiffs counsel solely to smear corporate defendants and defense expert witnesses. Most clear-eyed trial judges have quashed these efforts on various grounds, including Rule 703, because the books are not the sort of material upon which scientists would reasonably rely.[7]

In 2002, David Michaels created an anti-Daubert advocacy organization, the Project on Scientific Knowledge and Public Policy (SKAPP), from money siphoned from the plaintiffs’ common-benefit fund in MDL 926 (silicone gel breast implant litigation).[8] Michaels lavished some of the misdirected money to prepare and publish an anti-Daubert pamphlet for SKAPP, in 2003.[9] In this anti-Daubert publications, and many others sponsored by SKAPP, Michaels and the SKAPP grantees typically acknowledged the source of SKAPP funding obliquely to hide that it was nothing more than plaintiffs counsels’ walking around money:

“I am also grateful for the support SKAPP has received from the Common Benefit Trust, a fund established pursuant to a court order in the Silicone Gel Breast Implant Liability litigation.”[10]

Many credulous lawyers, judges, and legal scholars were duped into believing that SKAPP, SKAPP publications, and SKAPP-sponsored publications were supported by the Federal Judicial Center.

Michaels directed a good amount of SKAPP’s anti-Daubert funding to support Professor Berger’s efforts in organizing a series of symposia on science and the law. Several of Berger’s SKAPP conferences were held in Coronado, California, and featured a predominance of scientists who work for the lawsuit industry and are affiliated with advocacy organizations, such as the Collegium Ramazzini. The papers from one of the Coronado Conferences were published in a special issue of the American Journal of Public Health, the official journal of the American Public Health Association,[11] which has issued position papers highly critical of Rule 702 gatekeeping.[12]

The spider web of connections between SKAPP, the Collegium Ramazzini, the American Public Health Association, the Tellus Institute, the lawsuit industry,  Professor Berger, and others hostile to Rule 702 is a testament to the concerted action to undermine the Supreme Court’s decisions in the area, and the codification of those decisions in Rule 702. That Professor Berger was within this web of connections, and was writing the chapter on the admissibility of expert witness opinion testimony, in the first three editions of the Reference Manual, explains but does not justify many of the opinions contained within those chapters.

Professor David Bernstein, who has written extensively on expert witness issues, restated the situation thus:

“In 2003, the toxic tort plaintiffs’ bar used money from a fund established as part of the silicone breast implant litigation settlement to sponsor four conference in Coronado, California, that resulted in a slew of policy papers excoriating the Daubert gatekeeping requirement.”[13]

The active measures of these groups and Professor Berger explain the straight line between Berger’s symposia and the First Circuit’s decision in Milward v. Acuity Specialty Products Group, Inc.[14] Carl Cranor was one of the speakers at the Coronado Conferences, and along with Martyn Smith, another member of the Collegium Ramazzini, founded a Proposition 65 bounty-hunting organization, Council for Education on Research on Toxics (CERT). Cranor has long advocated for a loosey-goosey “weight of the evidence” approach that had been rejected by the Supreme Court in Joiner.[15] Cranor, along with Smith, unsurprisingly turned up as expert witnesses for plaintiff in Milward, in which case they reprised their weight-of-the evidence approach opinions. When Milward appealed the exclusion of Cranor and Smith, CERT filed an amicus brief, without disclosing that Cranor and Smith were founders of the organization, and that CERT funded Smith’s research through donations to his university, from CERT’s shake-down operations under Prop 65. The First Circuit’s 2011 decision in Milward resulted from a fraud on the court.

Professor Berger died in November 2010, but when the third edition of the Manual was released in 2011, it contained Berger’s chapter on the law of expert witnesses, with a citation to the Milward case, decided after her death.[16] An editorial note from an unnamed editor to her posthumous chapter suggested that

“[w]hile revising this chapter Professor Berger became ill and, tragically, passed away. We have published her last revision, with a few edits to respond to suggestions by reviewers.”

Given that Berger was an ideological opponent of expert witness gatekeeping, there can be little doubt that she would have endorsed the favorable references to Milward made after her passing, but adding them can hardly be considered non-substantive edits. Curious readers might wonder who was the editor who took such liberties of adding the chapter citations to Milward. Curious readers do not have to wonder, however, what would have happened if the incestuous relationships among Berger, SKAPP, the plaintiffs’ bar, and others had been replicated by similar efforts of manufacturing industry to influence the interpretation and application of the law. In 2008, the Supreme Court decided an important case involving constitutional aspects of punitive damages. The Court went out of its way to decline to rely upon empirical research that showed the unpredictability of punitive damage awards because it was funded in part by Exxon:

“The Court is aware of a body of literature running parallel to anecdotal reports, examining the predictability of punitive awards by conducting numerous ‘mock juries’, where different ‘jurors’ are confronted with the same hypothetical case. See, e.g., C. Sunstein, R. Hastie, J. Payne, D. Schkade, & W. Viscusi, Punitive Damages: How Juries Decide (2002); Schkade, Sunstein, & Kahneman, Deliberating About Dollars: The Severity Shift, 100 Colum. L.Rev. 1139 (2000); Hastie, Schkade, & Payne, Juror Judgments in Civil Cases: Effects of Plaintiff’s Requests and Plaintiff’s Identity on Punitive Damage Awards, 23 Law & Hum. Behav. 445 (1999); Sunstein, Kahneman, & Schkade, Assessing Punitive Damages (with Notes on Cognition and Valuation in Law), 107 Yale L.J. 2071 (1998). Because this research was funded in part by Exxon, we decline to rely on it.”[17]

Unlike the situation with SKAPP, David Michaels, the plaintiffs’ bar, and Professor Berger, the studies sponsored in part by Exxon had disclosed their funding clearly. Those studies involved outstanding scientists whose integrity were unquestionable, and for its trouble, Exxon was rewarded with gratuitous shaming from Justice Souter. The anti-Daubert papers sponsored by the plaintiffs’ bar through SKAPP, and Professor Berger’s ideological conflicts of interest have received a free pass. This disparate treatment between conflicts of interest within manufacturing industry and those within the lawsuit industry and its advocacy group allies is a serious social, political, and legal problem. It was a problem on full display in the now-retracted climate science chapter in the Manual. In evaluating the new fourth edition’s chapter on the law of expert witness admissibility (and other chapters), we should be asking whether there are signs of undue political influence.


[1] See Schachtman, The Late Professor Berger’s Introduction to the Reference Manual on Scientific Evidence, TORTINI (Oct. 23, 2011).

[2] See generally Edward K. Cheng, Introduction: Festschrift in Honor of Margaret A. Berger, 75 BROOKLYN L. REV. 1057 (2010). 

[3] Margaret A. Berger, Eliminating General Causation: Notes towards a New Theory of Justice and Toxic Torts, 97 COLUM. L. REV. 2117 (1997).

[4] See, e.g., Margaret A. Berger & Aaron D. Twerski, “Uncertainty and Informed Choice:  Unmasking Daubert,” 104 MICH. L.  REV. 257 (2005). 

[5] In re School Asbestos Litig., 977 F.2d 764 (3d Cir. 1992). See Cathleen M. Devlin, Disqualification of Federal Judges – Third Circuit Orders District Judge James McGirr Kelly to Disqualify Himself So As To Preserve ‘The Appearance of Justice’ Under 28 U.S.C. § 455 – In re School Asbestos Litigation (1992), 38 VILL. L. REV. 1219 (1993); Bruce A. Green, May Judges Attend Privately Funded Educational Programs? Should Judicial Education Be Privatized?: Questions of Judicial Ethics and Policy, 29 FORDHAM URB. L. J. 941, 996-98 (2002).

[6] David Michael, DOUBT IS THEIR PRODUCT: HOW INDUSTRY’S WAR ON SCIENCE THREATENS YOUR HEALTH (2008); David Michaels, THE TRIUMPH OF DOUBT (2020).

[7] See In re DePuy Orthopaedics, Inc. Pinnacle Hip Implant Prods. Liab. Litig., 888 F.3d 753, 787 n.71 (5th Cir. 2018) (advising the district court to weigh carefully whether Doubt is Their Product has any legal relevance); King v. DePuy Orthopaedics, Inc., 2024 WL 6953089, at *2 (D. Ariz. July 9, 2024) (finding Michaels’ books to be legally irrelevant); Sarjeant v. Foster Wheeler LLC, 2024 WL 4658407, at *1 (N.D. Cal.Oct. 24, 2024) (ruling that Doubt Is Their Product is legally irrelevant hearsay, and not the type of material upon which an expert witness would rely to form scientific opinion). See also Evans v. Biomet, Inc., 2022 WL 3648250, at *4 (D. Alaska Feb. 1, 2022) (quashing plaintiff’s subpoena to defendant’s expert for material in connection with Doubt Is Their Product).

[8] See Ralph Klier v. Elf Atochem North America Inc., 2011 U.S. App. LEXIS 19650 (5th Cir. 2011) (holding that district court abused its discretion in distributing residual funds from class action over arsenic exposure to charities; directing that residual funds be distributed to class members with manifest personal injuries). A “common benefit” fund is commonplace in multi-district litigation of mass torts.  In such cases, federal courts may require the defendant to “hold back” a certain percentage of settlement proceeds, to pay into a fund, which is available to those plaintiffs’ counsel who did “common benefit work,” work for the benefit of all claimants.  Plaintiffs’ counsel who worked for the common benefit of all claimants may petition the MDL court for compensation or reimbursement for their work or expenses.  See, e.g., William Rubenstein, On What a ‘Common Benefit Fee’ Is, Is Not, and Should Be, CLASS ACTION ATT’Y FEE DIG. 87, 89 (Mar. 2009).  In the silicone gel breast implant litigation (MDL 926), plaintiffs’ counsel on the MDL Steering Committee undertook common benefit work in the form of developing expert witnesses for trial, and funding scientific studies.  By MDL Orders 13, and 13A, the Court set hold-back amounts of 5 or 6%, and later reduced the amount to 4%.  Id. at 94.

[9] Eula Bingham, Leslie Boden, Richard Clapp, Polly Hoppin, Sheldon Krimsky, David Michaels, David Ozonoff & Anthony Robbins, Daubert: The Most Influential Supreme Court Ruling You’ve Never Heard Of (June 2003). The authors described the publication as a publication of SKAPP, coordinated by the Tellus Institute, and funded by The Bauman Foundation, a private foundation that supports “progressive social change advocacy.” Boden, Hoppin, Michaels, and Ozonoff are fellows of the Collegium Ramazzini.

[10] David Michael, DOUBT IS THEIR PRODUCT: HOW INDUSTRY’S WAR ON SCIENCE THREATENS YOUR HEALTH 267 (2008). See Nathan Schachtman, “SKAPP A LOT,” TORTINI (April 30, 2010); “Manufacturing Certainty” TORTINI (Oct. 25, 2011); “David Michaels’ Public Relations Problem” TORTINI (Dec. 2, 2011); “Conflicted Public Interest Groups” TORTINI (Nov. 3, 2013). 

[11] 95 AM. J. PUB. HEALTH S1 (2005).

[12] See, e.g., Am. Pub. Health Assn, Threats to Public Health Science, Policy Statement 2004-11 (Nov. 9, 2004), available at https://www.apha.org/policy-and-advocacy/public-health-policy-briefs/policy-database/2014/07/02/08/52/threats-to-public-health-science

[13] David E. Bernstein & Eric G. Lasker, Defending Daubert: It’s Time to Amend Federal Rule of Evidence, 702, 57 WM. & MARY L. REV. 1, 39 (2015), available at https://scholarship.law.wm.edu/wmlr/vol57/iss1/2. See David Michaels & Neil Vidmar, Foreword, 72 LAW & CONTEMP. PROBS. i, ii (2009) (“SKAPP has convened four Coronado Conferences.”).

[14] Milward v. Acuity Specialty Products Group, Inc., 639 F.3d 11 (1st Cir. 2011), cert. denied sub nom., U.S. Steel Corp. v. Milward, 132 S. Ct. 1002 (2012).

[15] General Electric Co. v. Joiner, 522 U.S. 136, 136-37 (1997).

[16] Margaret A. Berger, The Admissibility of Expert Testimony, in National Academies of Sciences, Engineering and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 11, 20 n.51, 23-24 n.61 (3rd 2011).

[17] Exxon Shipping Co. v. Baker, 554 U.S. 471, 128 S. Ct. 2605, 2626 n.17 (2008).

The First Daubert Motion

February 20th, 2026

As every school child knows, or at least every law student in the United States knows, Daubert was a Bendectin case. The plaintiff claimed that his mother’s use of Bendectin, a prescription anti-nausea medication, during pregnancy caused him to be born with a major limb reduction defect.

Filed in 1984, the Daubert case was pending, in summer 1989, before Judge Earl Ben Gilliam, in the Southern District of California. A trial date was approaching, and a deadline for motions for summary judgment. The first Daubert motion was filed in August 1989, in Daubert v. Merrell Dow Pharmaceuticals, Inc.[1] It was a motion for summary judgment, not a motion specifically to exclude plaintiffs’ expert witness’s proffered testimony.

By the time of the first Daubert motion, the plaintiff was relying upon the anticipated testimony of John Davis Palmer, M.D. For the time, John Davis Palmer was not an unlikely expert witness. Although Palmer practiced internal medicine, he had a doctorate in pharmacology. Palmer, however, had no experience studying Bendectin, and no real expertise in epidemiology. He had never designed or published an epidemiologic study, and he had never done any kind of research on Bendectin. The standard for qualifying an expert witness, even in federal court, has always been very low, and thus not an effective way to police the quality of scientific evidence.

Palmer was a rather late substitute for expert witnesses previously listed by the plaintiff. Alan Kimball Done, a pediatrician, had been the main warhorse of the Bendectin plaintiffs, but he was withdrawn by plaintiff’s counsel after he was found to have committed perjury about his academic credentials in another Bendectin case.[2]

Plaintiff also needed to drop another expert witness, William Griffith McBride, who had been a star in plaintiff’s counsel’s stable. McBride helped show the teratogenicity of thalidomide in the early 1960s,[3] and his work in the Bendectin litigation gave these dodgy cases some patina of respectability. In 1988, however, McBride was accused of fraud, for which he would eventually lose his medical license.[4] McBride also chose, rather improvidently, to sue journalists, journals, and Merrell Dow executives, for reporting his rather extensive fees, only to lose that litigation.[5] When plaintiff’s counsel withdrew McBride, plaintiff was left with only Dr. Palmer to serve as plaintiff’s sole expert witness on both general and specific causation.

At the time that the first Daubert motion was filed, manufacturer Merrell Dow had voluntarily withdrawn Bendectin from the market, without any suggestion from the FDA that this action was necessary or in the public interest. The manufacturer had also enjoyed considerable success in court. The company had tried a case that consolidated the general causation claims of over 800 plaintiffs, to a defense jury verdict, in 1985, before Chief Judge Carl Rubin, of the Southern District of Ohio.[6] Despite some isolated trial losses, the company was vindicated in three federal circuits at the time its lawyers filed the “Daubert” motion.[7] The First, Fifth, and District of Columbia Circuits of the United States Court of Appeals, had all held that the plaintiffs’ case was legally insufficient to sustain a verdict against the defendant, or that the expert testimony involved was inadmissible.

In the Daubert case, Merrell Dow Pharmaceuticals was represented by the law firm Dickson, Carlson & Campillo. The important task of drafting the motion for summary judgment landed on the desk of a first year associate, Pamela Yates, who is now a partner at Arnold & Porter. Given that Merrell Dow had succeeded in other appellate courts, the task may have seemed straight forward, but the legal theories were actually all over the map.

The first Daubert motion was not styled as a motion to exclude expert witness opinion testimony, but rather as a motion for summary judgment, pursuant to Federal Rule of Civil Procedure 56, on the issue of causation. Merrell Dow’s supporting brief did not clearly invoke the distinction between general and specific causation, which distinction was not widely drawn until later in the 1990s. The supporting brief implicitly addressed both general and specific causation.

At the time that the first Daubert motion was made, there was no clear consensus of precedent that identified the source of support for a trial court’s ruling peremptorily on a weak evidentiary display on the causation issue. The evidence supporting the defense expert witnesses’ opinion that Bendectin had not been shown to cause birth defects generally and limb reduction defects specifically was strong. For all major congenital defects, there had been no change in overall incidence for the years in which Bendectin was marketed. Such an ecological argument usually has no validity, but in the case of Bendectin, for several years, roughly half of all pregnant women used the medication. When the medication was abruptly withdrawn,[8] not because of the science but because of the cost of the litigation, the rate of birth defects remained unaffected. The great majority of birth defects have no known cause, and there was no scientific consensus that Bendectin caused birth defects; indeed by 1989, the nearly universal consensus was that Bendectin did not cause birth defects.[9]

There were also many analytical epidemiologic studies, which both individually or in combination failed to support a conclusion of causation.

In the face of the defense’s affirmative evidence, the plaintiff relied upon a potpourri of evidence:

1) chemical structure activity analysis;

2) in vitro (test tube) studies;

3 ) in vivo studies (animal teratology) studies; and

4) reanalysis of epidemiology studies.

Plaintiff’s lead counsel Barry Nace[10] had concocted this potpourri approach, which he called “mosaic theory,” and which might more aptly be called the tsemish or the shmegegge theory.[11] Whatever Nace called it, he fed it to his expert witness to argue that:

“Like the pieces of a mosaic, the individual studies showed little or nothing when viewed separately from one another, but they combined to produce a whole that was greater than the sum of its parts: a foundation for Dr. Done’s opinion that Bendectin caused appellant’s birth defects.”[12]

Although philosopher Harry Frankfurt had not yet written his seminal treatise on the subject, most courts saw that this was bullshit, which tends to result “whenever a person’s obligations or opportunities to speak about some topic exceed his knowledge of the facts that are relevant to that topic.”[13]

In addition to favorable opinions from the First, Fifth, and District of Columbia Circuits, Merrell Dow had a favorable Zeitgeist working in its favor. The plaintiff-friendly influential judge, Judge Jack Weinstein, had rolled up his sleeves and taken a hard look at the plaintiffs’ scientific evidence in the Agent Orange litigation. Judge Weinstein found that evidence wanting in an important opinion in 1985.[14] Although the alleged causal agent in Agent Orange was not Bendectin, Judge Weinstein recognized that epidemiological studies were, in a similar medico-legal context, “the only useful studies having any bearing on causation.[15] Judge Weinstein relied heavily upon Federal Rule of Evidence Rule 703, which governed what inadmissible studies expert witnesses could rely upon, to whittle down the reliance list of plaintiffs’ expert witnesses before declaring their opinions too fragile to support a reasonable jury’s verdict in favor of plaintiffs.

More generally, discerning members of the legal system were reaching the end of their tolerance for the common law laissez-faire approach to expert witness evidence. In 1986, the Department of Justice issued a report that explicitly called for meaningful judicial gatekeeping of expert witnesses.[16] And in that same year, 1986, Judge Patrick Higginbotham wrote an influential opinion, in which he warned that expert witness opinion testimony was out of control, with expert witnesses becoming mouth pieces for the lawyers and advocates of policy beyond their proper role. Judge Higginbotham observed that trial judges (with support from appellate court judges) had a duty to address the problem by policing the soundness of opinions proffered in litigation, and to reject the system’s reliance upon expert witnesses simply because they “say[] it is so:”[17]

“we recognize the temptation to answer objections to receipt of expert testimony with the short hand remark that the jury will give it ‘the weight it deserves’. This nigh reflective explanation may be sound in some cases, but in others it can mask a failure by the trial judge to come to grips with an important trial decision. Trial judges must be sensitive to the qualifications of persons claiming to be experts … . Our message to our able trial colleagues: It is time to take hold of expert testimony in federal trials.”[18]

Although Merrell Dow had a substantial tailwind behind its motion for summary judgment, there was no one clear theory upon which it could rely. Some of the Bendectin appellate court opinions were based upon the insufficiency of the plaintiffs’ expert witness evidence, on the basis of the entire record after trial. The evidence in Daubert was virtually the same if not more restricted than what was of record in some of those appellate court cases. The ecological evidence was clear.

Some of the judgments relied upon by Merrell Dow were based upon the Frye test, and some were based upon Rule 703, which addresses what kinds of otherwise inadmissible evidence expert witnesses may rely upon in formulating their opinions. Finally, some courts, such as Fifth Circuit in In Re Air Crash Disaster at New Orleans, were beginning to see Rule 702 as the source of their authority to control wayward expert witness opinion testimony.

Merrell Dow advanced multiple lines of analyses to show that plaintiffs cannot establish causation based upon the then current scientific record. The first Daubert motion had no clear line of authority, and so, understandably, it cast a wide net on all available potential legal rules and doctrines to oppose the plantiff’s potpourri Bendectin causation theory. The motion harnessed precedents based upon sufficiency of the plaintiffs’ proffered expert witness, Federal Rules 702 and 703, as well as the 1923 Frye case.[19]

The cases that invoked Frye doctrine presented several interpretative problems. Frye was a criminal case that prohibited expert witnesses from testifying about their interpretations of the output of a mechanical device. The Frye case’s insistence upon general acceptance, when imported into a causation dispute in a tort case, was ambiguous as to what exactly had to be generally accepted: the specific causal claim, or the method used to reach the causal claim, or the method used as applied to the facts of the case. Furthermore, Frye’s requirement of general acceptance was not explicitly incorporated into either Rule 702 or 703, when promulgated in 1975.[20]

Merrell Dow had ample evidence that there was no general acceptance of the plaintiff’s causal claim, but its counsel also showed that by applying generally accepted methodology, scientists could not reach the plaintiff’s causal conclusion, and no scientist outside of the litigation had done so. In particular, there was general acceptance of the propositions that non-human in vivo and in vitro teratology experiments have little if any predictive ability for human outcomes. Because randomized controlled trials were never an option for testing human teratogenicity, observational epidemiology was required, and the available studies were largely exonerative. Only by post-publication data dredging and manipulation was plaintiffs’ expert witness Palmer (following what Shann Swan had done in previous cases) able to raise questions about possible associations. Plaintiff’s expert witness Palmer could not show that these manipulations were a generally accepted method for interpreting or re-analyzing published studies.

In its last point, the first Daubert motion also maintained that the standard for medical causation required that the relevant relative risk exceed two.[21] As noted, the brief did not distinguish general from specific causation, a distinction that had not entered the legal lexicon fully in 1989. The brief’s citation to swine-flu cases, however, clarifies the nature of Merrell Dow’s argument. In the swine-flu litigation, the United States government assumed liability for adverse effects of a vaccine for swine flu. The government recognized that within a certain time window after vaccination, patients had more than a doubled risk of Guillain-Barré syndrome (GBS), an autoimmune neurological condition. The government refused compensation for claimants outside that window. Merrell Dow relied heavily upon one swine flu case, Cook v. United States, which articulated and applied the principle:

“Wherever the relative risk to vaccinated persons is greater than two times the risk to unvaccinated persons, there is a greater than 50% chance that a given GBS case among vaccinees of that latency period is attributable to vaccination, thus sustaining plaintiff’s burden of proof on causation.”[22]

In other words, the government had conceded that the swine-flu vaccine could cause GBS in some temporal situations, but not others. The magnitude of the causal association had been quantified in relative risk terms by epidemiologic studies. Only for those claimants vaccinated in time windows with relative risks greater than two could courts conclude that GBS was, more likely than not, caused by vaccination.

Unlike the federal government in the swine-flu GBS litigation, Merrell Dow was not, however, conceding general causation for any exposure scenarios. The first Daubert motion can only be read to deny general causation, but to explain further that even if the court were to assume, arguendo, that Bendectin causes limb reduction deficits based upon Palmer’s schmegegge and Swan’s re-jiggered risk ratios, that there would still be no proper inference that Bendectin more likely than not caused Jason Daubert’s birth defects.

In response to these arguments, the plaintiff’s counsel argued their mosaic, potpourri, schmegegge theories. Although plaintiffs were down to Dr. Palmer, they filed transcripts and affidavits from a host of other expert witnesses, from previous Bendectin cases.

As for the legal rules of decision, Barry Nace, on behalf of plaintiffs, argued that Rule 703 had “absorbed” the Frye rule. Having been shown to be qualified under the minimal standard of Rule 702, these expert witnesses then satisfied Rule 703 by relying upon “scientific evidence” of the sort that experts in their field rely upon, even if other scientists would not rely upon such evidence in support of a conclusion. Otherwise those expert witnesses were unrestrained by the law, and they were free to assess their relied upon facts and data as sufficient to show that Bendectin probably causes birth defects and that Bendectin caused Jason Daubert’s birth defects. Nace argued that as long as expert witnesses, properly qualified, offered relevant opinions, based upon “things of science,” they could opine that the earth was flat, and it was for the jury to sort out whether to believe them.

Judge Earl Gilliam found Nace’s position untenable, and granted summary judgment later in 1989.[23] Interestingly Judge Gilliam’s opinion in the district court never cited Federal Rule of Evidence 702. Instead, the opinion pointed to Rule 703, as restricting evidence, even if “science,” unless the proponent showed that the underlying principle had gained general acceptance in the relevant field.[24] Opinions not based upon facts or data “of a type reasonably relied upon by experts in the particular field” would be confusing, misleading, and unhelpful, and thus inadmissible. The reference to helpfulness might perhaps be taken as an implicit invocation of Rule 702.

Judge Gilliam had the benefit of the Circuit decisions in Brock, Richardson, and Lynch, with their various holdings of insufficiency or inadmissibility of plaintiffs’ expert witness evidence. In particular, Judge Gilliam cited Brock for the proposition that trial courts must “critically evaluate the reasoning process by which the experts connect data to their conclusions in order for courts to consistently and rationally resolve the disputes before them.”[25] Following Judge Weinstein on Agent Orange, and the previous federal decisions on Bendectin, Judge Gilliam observed that causation in the Bendectin cases could be established, under the circumstances of plaintiffs’ evidentiary display, only through reliance upon epidemiologic evidence. Dr. Done’s schmeggege, concocted as it was by Barry Nace, would not get plaintiffs to a jury.

Judge Gilliam went further to point out that some of plaintiffs’ proffer did not even purport to claim causation. Shanna Swan’s prior testimony asserted that Bendectin was “associated” with limb reduction. Jay Glasser, a specialist in biostatistics, epidemiology and biometry had opined that “Bendectin is within a reasonable degree of epidemiological certainty associated with congenital disorders, including limb defects.” Dr. Johannes Thiersch, a specialist in pathology and pharmacology, proclaimed that “structure analysis” was “of great interest.”[26] In other words, there was a good deal of true, true, but immaterial opinion in what Mr. Nace had thrown over the transom, in opposition to the motion for summary judgment.

Nace appealed, and the Daubert case was argued to the Ninth Circuit in 1991. In a short opinion by Judge Kozinski, the appellate court affirmed the judgment below.[27] The affirmance did not mention Rule 702; rather it relied upon the decisions of other Circuits, in which the plaintiffs’ evidentiary display had been found insufficient to sustain a reasonable jury verdict.

Judge Kozinski’s opinion tilted towards Rule 703 and the Frye standard in citing to cases that stated, based upon Frye, that expert witnesses must use generally accepted techniques from the scientific community. As a legal determination, the determination of general acceptance vel non was a legal determination reviewable de novo. For its de novo decision on general acceptance, the Ninth Circuit relied upon the cases coming from the First, Fifth, and District of Columbia Circuits,[28] and of course, the record below.

By 1991, another Circuit, the Third, had weighed in on the same evidentiary display, when it reversed summary judgment for Merrell Dow, and remanded for reconsideration under the Third Circuit’s approach to Rule 702. Judge Kozinski declared that the Third Circuit’s approach was not followed in the Ninth Circuit, and proceeded to ignore the DeLuca case.[29]

Judge Kozinski treated the insufficiency and the invalidity of the Nace/Done schmeggege theory as legal precedent, and thus the court’s opinion gave very little attention by way of expository description or explanation of the problems with the four factors (in vitro, in vivo, structure analysis, and re-analysis of epidemiologic studies). As Judge Kozinski put the matter:

 “For the convincing reasons articulated by our sister circuits, we agree with the district court that the available animal and chemical studies, together with plaintiffs’ expert reanalysis of epidemiological studies, provide insufficient foundation to allow admission of expert testimony to the effect that Bendectin caused plaintiffs’ injuries.”[30]

And thus, summary judgment was proper in Daubert. Judge Kozinksi, like Judge Gilliam in the district court, never reached the specific causation argument that involved risk ratios less than two.

Some of the Circuit court cases relied upon by Judge Kozinski delved into the invalidity of these methods for determining the causes of human birth defects. The Lynch decision explored in some detail the Shanna Swan made-for-litigation rejiggering of a study based upon data from the Metropolitan Atlanta Congenital Defects Program, which included a challenge to whether it could be reasonably relied upon (Rule 703), as well as its pretense to support a scientific conclusion (Rule 702).[31] Later commentators would skirt the validity issue by asserting that re-analysis, in the abstract, is not impermissible or invalid, without addressing the specific issues discussed in the reported decisions. Other commentators have misrepresented Swan’s re-analysis as a meta-analysis, which it was not.

Some commentators have complained that the defense in Daubert made too much of the lack of statistical significance. Their complaint, in the abstract, might have some salience. In some contexts, an isolated and elevated risk ratio greater or less than one may well have important information, even if the p-value is a bit above 0.05. The lack of statistical significance at the conventional five percent, however, conveys important information about the finding’s imprecision, especially when there was a large dataset to evaluate. In 1994, a meta-analysis was published that found a summary estimate of all birth defects in the available epidemiologic studies to be an odds ratio of 0.95 (95% C.I., 0.88-1.04), and the summary estimate for limb reduction defects to be an odds ratio 1.12 (95% C.I., 0.83-1.48).[32]


[1] Defendant’s Memorandum of Points and Authorities in Support of Its Motion for Summary Judgment on the Issue of Causation, Daubert v. Merrell Dow Pharms., Inc., Case No. 84-2013-G(I) (S.D. Cal. Aug. 2, 1989). The motion was made in a companion case before Judge Gilliam as well, Schuller v. Merrell Dow Pharms., Inc., Case No. 84-2929-G(I). The first Daubert motion may not have been the first one drafted. The linked brief is the first one as filed.

[2] See Oxendine v. Merrell Dow Pharms., Inc., 563 A.2d 330 (D.C. Ct. App. 1989).

[3] William Griffith McBride, Thalidomide and Congenital Abnormalities, 278 LANCET 1358 (1961).

[4] William Griffith McBride, McBride criticizes inquiry, 336 NATURE 614 (1988); Norman Swan, Disciplinary tribunal for McBride, 299 BRIT. MED. J. 1360 (1989); G. F. Humphrey, Scientific fraud: the McBride case, 32 MED. SCI. LAW 199 (1992); Mark Lawson, McBride found guilty of fraud, 361 NATURE 673 (1993); Leigh Dayton, Thalidomide hero found guilty of scientific fraud, NEW SCI. (Feb.27, 1993); William McBride: alerted the world to the dangers of thalidomide in fetal development, 362 BRIT. MED. J. k3415 (2018).

[5] McBride v. Merrell Dow & Pharms., Inc., 800 F.2d 1208 (D.C. Ct. App. 1986). McBride ultimately failed against all his litigation targets.

[6] See In Re Richardson-Merrell. Inc. Bendectin Prods. Liab. Litig., 624 F.Supp. 1212 (S.D. Ohio 1985); aff’d sub nom. In re Bendectin Litig., 857 F.2d 290 (6th Cir. 1988); cert. denied, 488 US 1006 (1989).

[7] Brock v. Merrell Dow Pharmaceuticals Inc., 874 F.2d 307 (5th Cir. 1989); Richardson y. Richardson-Merrell, 857 F.2d 823 (D.C. Cir. 1988); Lynch v. Merrell-National Labs., 830 F.2d 1190 (1st Cir. 1987) (affirming grant of summary judgment).

[8] US Food & Drug Admin., Determination That Bendectin Was Not Withdrawn from Sale for Reasons of Safety or Effectiveness, 64 FED. REG. 43190–1 (1999).

[9] Brief at 3-4.

[10] Barry Nace was one of the lead plaintiffs’ counsel in the Bendectin litigation, and he represented the Daubert family. Nace was also formerly President of the lawsuit industry’s principal lobbying organization, the American Trial Lawyers Association (now the AAJ). See also In re Barry J. Nace, A Member of the Bar of the District of Columbia Court of Appeals (Bar Registration No. 130724), No. 13–BG–1439, Slip op. (Sept. 4, 2014), available at <https://www.dccourts.gov/sites/default/files/pdf-opinions/13-BG-1439.pdf>, last visited on Feb. 8, 2026.

[11] See Michael D. Green, Pessimism about Milward, 3 WAKE FOREST J. L & POL’Y 41, 63 (2013) (paraphrasing Nace as describing the mosaic theory as “[d]amn brilliant, and I was the one who thought of it and fed it to Alan [Done].”).

[12] Id. at 61 (2013) (citing Oxendine v. Merrell Dow Pharm., Inc., 506 A.2d 1100, 1110 (D.C. 1986).

[13] Harry Frankfurt, ON BULLSHIT 63 (2005).

[14] In re “Agent Orange” Prod. Liab. Litig., 611 F. Supp. 1223 (E.D.N.Y. 1985), aff’d, 818 F.2d 187 (2d Cir. 1987), cert. denied, 487 U.S. 1234 (1988).

[15] Id. at p. 1231.

[16] United States Dep’t of Justice, Tort Policy Working Group, Report of the Tort Policy Working Group on the causes, extent and policy implications of the current crisis in insurance availability and affordability at 35 (Report No. 027-000-01251-5) (Wash. DC 1986), available at https://archive.org/details/micro_IA41152903_0369.

[17] In Re Air Crash Disaster at New Orleans, 795 F.2d 1230, 1233-34 (5th Cir. 1986).

[18] Id. at 1233-34.

[19] The Brief, at 2, cited United States v. Kilgus, 571 F.2d 508, 510 (9th Cir. 1987) (citing Frye).

[20] An Act to Establish Rules of Evidence for Certain Courts and Proceedings. Pub. L. 93–595, 88 Stat. 1926 (1975).

[21] Brief at 17.

[22] 545 F.Supp. 306, 308 (N.D. Cal. 1982). See generally Richard E. Neustadt & Harvey V. Fineberg, THE SWINE FLU AFFAIR: DECISION-MAKING ON A SLIPPERY DISEASE (Nat’l Acad. Sci. 1978).

[23] Daubert v. Merrell Dow Pharms., Inc., 727 F.Supp. 570 (S.D. Cal. 1989).

[24] Id. at 571, citing United States v. Kilgus, 571 F.2d 508, 510 (9th Cir.1978).

[25] Id. at 572 (citing Brock, 874 F.2d at 310).

[26] Id. at 574. The use of “association” was at best ambiguous, because it begged the question whether it as an association that was “clear cut” (reasonably free from bias and confounding), and beyond that which we would care to attribute to chance.

[27] Daubert v. Merrell Dow Pharms., Inc., 951 F.2d 1128 (9th Cir. 1991).

[28] Brock v. Merrell Dow Pharms., Inc., 874 F.2d 307, modified, 884 F.2d 166 (5th Cir.1989), cert. denied, 494 U.S. 1046 (1990); Richardson v. Richardson–Merrell, Inc., 857 F.2d 823 (D.C.Cir.1988), cert. denied, 493 U.S. 882 (1989); Lynch v. Merrell–National Labs., 830 F.2d 1190 (1st Cir.1987).

[29] DeLuca v. Merrell Dow Pharmaceuticals, Inc., 131 F.R.D. 71 (D.N.J.) (granting summary judgment), rev’d and remanded, 911 F.2d 941 (3d Cir.1990). On remand, the district court entered summary judgment on the alternative reasoning of Rule 702, as interpreted by the Third Circuit. DeLuca v. Merrell Dow Pharms., Inc., 791 F.Supp. 1042, 1048 (D.N.J. 1992) (re-entering summary judgment after considering Rule 702), aff’d, 6 F.3d 778 (3d Cir.1993) (per curiam), cert. denied, 510 U.S. 1044 (1994).

[30] Daubert v. Merrell Dow Pharms., Inc., 951 F.2d 1128, 1131 (9th Cir. 1991).

[31] Lynch v. Merrell–National Labs., 830 F.2d 1190, 1194-95 (1st Cir.1987).

[32] Paul M. McKeigue, Steven H. Lamm, Shai Linn & Jeffrey S. Kutcher, Bendectin and Birth Defects: I. A Meta-Analysis of the Epidemiologic Studies, 50 TERATOLOGY 27 (1994). This meta-analysis made no correction for multiple comparisons in examining many different types of birth defects.

The FJC Retracts Climate Science – Postscriptum

February 11th, 2026

The version of the Reference Manual on the NASEM website still has the climate science chapter.

The FJC website has a version without the climate science chapter. There is a note that the chapter was removed on February 6, 2026.

Perhaps the two organizations should talk?

The FJC retraction has been covered by many media outlets, but the failure of NASEM to act has not been reported, as far as I can see.[1]


[1] See, e.g., Nate Raymond, US judiciary scraps climate chapter from scientific evidence manual, REUTERS (Feb. 9, 2026)

The FJC Retracts Climate Science Chapter in New Reference Manual

February 10th, 2026

When the new, fourth, edition of the Reference Manual on Scientific Evidence was released late last year,[1] I remarked that there were some new chapters,[2] including one on climate change. I found the addition of a chapter on climate change curious largely because I was unfamiliar with the science or the need to address the area for federal judges, and because I thought there were other more pressing topics, such as genetic causation, from which judges could benefit, but which were not included.

I confess that I did not read the new chapter on climate change,[3] which is not a subject that comes up in my practice or in my writing. Writers at the National Review, however, did read the chapter on climate, and found it objectionable. Writing on January 17th of this year, Michael Fragoso observed that the chapter on climate science was an advocacy piece that would resolve climate change litigation in favor of plaintiffs.[4]

If Fragoso’s charge is correct, the implications are extremely serious. Judges have an ethical obligation not to go beyond the adversary process to educate themselves about the factual issues before them in pending litigation. In the past, judges who have done so have found themselves on the wrong end of a petition for a writ of mandamus, and have been disqualified and removed from cases.[5] The Federal Judicial Center (FJC), which is the research and educational division of the federal courts, has tried to create a safe space for teaching judges about technical subjects that arise in litigation in a way that is balanced and removed from partisan advocacy. The last edition, the third, and the current edition, the fourth, of the Manual have been the joint product of the both the FJC and the National Academies of Science, Engineering and Medicine (NASEM), in the hope of producing disinterested tutorials on key areas of science that are important to judges in their adjudication of civil and criminal cases, as well as their performance of judicial review of regulation and agency action.

Following up on the National Review article, on January 29, 2026, the Attorneys General of 24 states[6] wrote a letter to Judge Robin Rosenberg, the director of the Federal Judicial Center. The letter identified the advocacy perspective of the climate chapter and its authors, who wrote what the Attorneys General described as an amicus brief that placed a thumb on the scales of justice, with respect to issues currently pending at all levels of the federal courts. The Attorneys General requested the immediate withdrawal of the offending chapter.

Judge Rosenberg is a savvy judge of scientific horse flesh. She presided over the Zantac multi-district litigation (MDL No. 2924), in which she excluded plaintiffs’ expert witnesses in a detailed, analytically careful opinion of over 300 pages.[7] On February 6, a week after the request to withdraw the climate chapter was made, Judge Rosenberg, wrote to West Virginia Attorney General John McCuskey, to report that the chapter had been omitted.[8] Given the prompt response from Judge Rosenberg, the decision was likely not a difficult one.  A decision not to include this chapter, as written, in the first place, would have been an even easier one.

Retractions of publications of the NASEM, which includes what was formerly the Institute of Medicine, are rarer than hens teeth.  This one received coverage and some intense harrumphing.[9] The retraction of the climate science chapter comes on the heels of a high-profile retraction, in December 2025, of an article in the prestigious journal Nature,[10] which argued that the costs of climate change would reach $38 trillion a year by 2049.[11]

The climate science chapter appears to be the outcome of what the late Daniel Kahneman called poor decision hygiene.  The chapter in question had two authors, and both were from the same institution, published together, and shared the same advocacy perspectives on climate change. Hardly a team of rivals. The editors of the Manual certainly could have done better in selecting these authors and in editing the work product.

Jessica Wentz is a Non-Resident Senior Fellow at the Sabin Center for Climate Change Law, at the Columbia Law School. The Sabin Center website describes itself as “develop[ing] legal techniques to combat the climate crisis and advance climate justice, and train the next generation of leaders in the field.” The language of “combat” and “crisis” certainly suggests a hardened, adversarial stance. Wentz’s writings reveal her advocacy and adversarial positions.[12]

Radley Horton is a Professor at Columbia University’s Climate School. He describes his research as focusing on climate extremes, and related topics. Horton’s curriculum vitae, social media, social media, testimony,[13] and professional work certainly mark him as an advocate for “attribution science” in litigation to address climate crises. Horton and Wentz previously published a law review article that seems to be a brief for plaintiffs’ positions in climate litigation.[14] One of the key issues in climate litigation is whether litigation is an appropriate avenue for addressing climate issues, and Horton and Wentz have both clearly committed to endorsing litigation strategies, and the plaintiffs’ positions to boot.

This kerfuffle at FJC and NASEM has a larger meaning. There is a glib assumption afoot that the only conflicts of interest that matter are ones that are attributed to industrial stakeholders and their scientific supporters. This naïve view was attacked and debunked back in 1980, by Sir Richard Peto, writing in the pages of Nature. Sir Richard noted that whereas industry may downplay risks, “environmentalists usually exaggerate the likely hazards and are largely indifferent to the costs of control.” Positional conflicts can be, and often are, more powerful than the ones created by profit.[15]


[1] National Academies of Sciences, Engineering, and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE (4th ed. 2025) (cited as RMSE 4th ed.).

[2] Nathan Schachtman, A New Year, A New Reference Manual, in TORTINI (Jan. 5, 2026).

[3] Jessica Wentz & Radley Horton, Reference Guide on Climate Science, RMSE 4th ed.

[4] Michael A. Fragoso, Bias and the Federal Judicial Center’s ‘Climate Science’, NAT’L REV. (Jan. 17, 2026). Fragoso also took umbrage to the use of the silly phrase “pregnant people” elsewhere in the Manual. RMSE 4th ed. at 84.

[5] In re School Asbestos Litigation, 977 F.2d 764 (3d Cir. 1992). See Cathleen M. Devlin, Disqualification of Federal Judges – Third Circuit Orders District Judge James McGirr Kelly to Disqualify Himself So As To Preserve ‘The Appearance of Justice’ Under 28 U.S.C. § 455 – In re School Asbestos Litigation (1992), 38 VILL. L. REV. 1219 (1993);

[6] Alabama, Alaska, Arkansas, Florida, Georgia, Idaho, Indiana, Iowa, Missouri, Montana, Nebraska, New Hampshire, North Dakato, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakato, Tennessee, Texas, Utah, West Virginia, West Virginia, and Wyoming.

[7] In re Zantac (Ranidine) Prods. Liab. Litig., 644 F. Supp. 3d 1075 (S.D. Fla. 2022).

[8] Hon. Robin Rosenberg, Letter in Response to Attorneys General (Feb. 6, 2026).

[9] Editorial Board, A Failed Climate Coup in the Courts,  WALL ST. J. (Feb. 9, 2026); Charles Creitz, Judicial research center cuts climate section from judges’ manual, FOX NEWS (Feb. 9, 2026); Suzanne Monyak, Judiciary Cuts Climate Part of Science Manual after Backlash, BLOOMBERG LAW (Feb. 9, 2026).

[10] Maximilian Kotz, Anders Levermann & Leonie Wenz, The economic commitment of climate change, 628 NATURE 551 (2024) (retracted on Dec. 3, 2025).

[11] Authors retract Nature paper projecting high costs of climate change, RETRACTION WATCH (Dec. 3, 2025).

[12] Michael Burger, Jessica Wentz & Daniel Metzger, Climate science in rights-based advocacy contexts (June 28, 2020).

[13] Written Testimony of Radley Horton, Lamont Associate Research Professor, Columbia University, before the Committee on Science, Space, and Technology Subcommittee on Environment Sea Change: Impacts of Climate Change on Our Oceans and Coasts (Feb. 27, 2019).

[14] Michael Burger, Radley M. Horton & Jessica Wentz, The Law and Science of Climate Change Attribution, 45 COLUMBIA J. ENVT’L J. L. 57  (2020).

[15] Richard Peto, Distorting the epidemiology of cancer: the need for a more balanced overview, 284 NATURE 297, 297 (1980).

Selikoff’s Role in Establishing OSHA

February 1st, 2026

In May 1970, Selikoff testified in support of the Occupational Safety and Health Act of 1970, on which the Senate was then deliberating. By many accounts, Selikoff’s testimony helped overcome significant resistance to “federalizing” the workplace,[1] by establishing national standards for worker safety and health. Activists in the labor movement credit Selikoff’s testimony as a substantial factor in the creation of OSHA.[2]

Rhetorically, Selikoff’s presentation was brilliant. He showed up with two high-ranking officers of the Asbestos Workers Union,[3] Albert Hutchinson and Andrew Haas, and with Ivan Sabourin, Chief Legal Counsel for Johns Manville Corporation. The civil litigation against Johns Manville had not yet erupted, but the storm clouds were amassing. Tort litigation standards were undergoing a radical transformation, with the help of the American Law Institute’s Restatement Second of Torts.[4] In the late 1960s, sensationalist journalistic exposés of the asbestos mining and manufacturing industry received national attention,[5] and Johns Manville’s reputation was seriously damaged. Sabourin, no doubt, had a sense that he had to join with Selikoff to promote federal remedial legislation, and Selikoff exploited the opportunity to the hilt.

In his testimony, Selikoff made a compelling case for remedial occupational safety legislation, with muscular federal oversight and enforcement. Selikoff’s strongest argument was that national occupational safety standards, with federal enforcement, were in industry’s own best interests. Although some states had regulatory oversight of workplace safety, many states did not. Some states with strong regulation had weak enforcement. Manufacturers were inclined to build factories where they would have lower rather than higher compliance costs. Among manufacturers, competition undermined even safety-minded enterprises because caring companies could compete successfully only by shedding the costs and burden of worker protection.

Not only were conscientious employers often at a competitive disadvantage, they were often hurt directly by uncaring employers in their industry. Employees move around. Workers may be over-exposed to a hazardous substance, which has a long latency, at one employer, and then end up working for a more caring employer, when they manifest with an occupational disease. Worker’s compensation laws require the current, conscientious employer to foot the bill for the bad-acting former employer. Smaller employers might lack the knowledge to address the relevant health hazards at all.[6]

Selikoff saw these and other coordination problems as inuring to the detriment of workers because no one industry will invest in changes unless such remedial changes are introduced and enforced across all employers.[7] In Selikoff’s dramatic phrasing, “those who advocate weak occupational health legislation do industry no service at all and certainly do labor a great deal of harm.”[8]

On the positive side of the ledger, the control or elimination of hazardous exposures in the workplace would have a meaningful benefit to workers. Selikoff pointed to Great Britain and Germany, where reduced exposure limits for asbestos exposure in the workplace resulted in falling rates of asbestosis and lung cancer.[9] The difficult question Selikoff’s testimony raises is whether the benefits of national standards for worker safety and health justify his testimonial exaggerations and misrepresentations.

Misleading Statistics and Fake History

On science and history, Selikoff was on shakier ground much shakier grounds than his political arguments. In 1962, Selikoff began to assemble mortality data on a cohort of 632 insulators, New York and New Jersey asbestos workers union members, who had been on the union rolls in 1943. He first published their mortality data in 1964,[10] and at the Senate hearing, Selikoff presented an updated account through April 1967. In 1970, there still not many large, well-conducted epidemiologic studies available, and Selikoff’s small cohort of insulators had the most dramatic, and exaggerated mortality statistics. Valid or not, the Selikoff data were a powerful argument for pushing forward with a federal agency that would oversee hazardous workplace operations.

According to Selikoff’s testimony, of the 632 union workers, 405 had died. Among these 405 deaths, 32 insulators died of asbestosis. From litigation of some of these cases, however, it is clear that some of the “asbestosis” deaths were due to chronic emphysema caused by cigarette smoking, in the presence of concomitant asbestosis. In any event, Selikoff took the liberty of extrapolating from his small insulator cohort, and rounded up asbestosis mortality from 8 to 10 percent. Clearly, many of these 32 insulators had been exposed above the New York and New Jersey permissible exposure limits.

Selikoff testified that there had been 20 deaths due to mesothelioma, when only one in 10,000 deaths had been expected from this rare disease. Somehow the 5 percent of cohort deaths (20/405) became “one out of seven deaths,” or over 14 percent, at another point in Selikoff’s testimony, only to have Selikoff retreat back down to 10 percent (one of every 10 deaths), a few minutes later.

Selikoff’s handling of lung cancer mortality was equally confused and confusing. Of the 405 deaths, Selikoff reported that 66 deaths had been due to lung cancer. This 16 percent was then rounded up to one of five deaths (or 20 percent), moments later. In his Senate testimony, Selikoff did not report what the smoking prevalence had been among the 632 union insulators, and how it compared with his control group. Smoking accounts for 90 percent or so of lung cancer deaths in the United States. Selikoff’s cohort’s 16 percent lung cancer mortality is actually a bit less than 17 percent, what other general population studies have shown for smokers’ lung cancer rates.[11]

Selikoff also gave a confusing and inaccurate account of the history of the knowledge of asbestos cancer risks. At one point in his testimony, Selikoff recounted a 1935 case report by Kenneth Lynch. [12]According to Selikoff, Lynch had encountered at autopsy a man who had both lung cancer and asbestosis. Lynch regarded the clinical coincidence of the two diseases as remarkable, and wondered in a published case report whether the two diseases were causally related.[13]

As Selikoff held forth to the Senate subcommittee, his account of the Lynch case report became more exaggerated.[14] What at first was a 1935 report that asked a question became an assertion that “in 1935, Kenneth Lynch reported the association of asbestos work and lung cancer and warned that they were causally related.”[15]

The problem with Selikoff’s testimony was that Lynch had done no such thing. Lynch’s case report of a man who worked for 21 years in an asbestos factory raised the question of causality, but nowhere in the 1935 publication does Lynch issue a “warning” that asbestosis and lung cancer were causally related. Lynch never reported whether or not the 57 year-old white man had been a smoker. In trying to downplaying the unexplored smoking history, Selikoff embellishes upon the case report by asserting that not “many people smoked cigarettes … in 1910-1915.”[16]

This claim about smoking prevalence is also false, and part of Selikoff’s pattern of misrepresentations about smoking that were consistently designed to minimize the role of tobacco and maximize the role of asbestos in causing lung cancer.  World War I had a tremendous influence on both soldiers and the general population, with smoking prevalence among men rising dramatically after 1915. With the mass production of cigarettes, more than half of adult males in the United States smoked by 1920.[17] In September 1967, almost three years before testifying at the Senate hearings on the Occupational Health and Safety Act, Selikoff addressed a meeting of the asbestos workers international, and told them that he had

“yet to see a lung cancer in an asbestos worker who didn’t smoke cigarettes. … “[C]ancer of the lung could be wiped out in your trade if you people wouldn’t smoke cigarettes… .”[18]

Selikoff strategically omitted this detail from his Senate testimony.

On scientific and historical issues, Selikoff testified recklessly and with impunity to an audience of credulous Senators. Not only had Lynch not warned of a causal relationship in 1935, his case report was not capable of supporting such a causal inference. Case reports and series were certainly a commonplace in the medical literature, but by the early 1950s, the scientific community witnessed a dramatic shift in appreciating the need for controlled epidemiologic investigations to establish associations and causal associations.[19] Lynch’s 1935 case report had little scientific credibility after the success of lung cancer epidemiology in the 1950s.

Selikoff castigated the Public Health Service for not having researched the lung cancer issue through the 1950s. The lack of research, however, did not keep union physicians from claiming that asbestos caused lung cancer from at least the early 1950s.[20]

The Myth of the Innocent Asbestos Worker

Selikoff pressed his case for the need for national legislation by adverting to the supposed ignorance of the asbestos workers of the hazards of their trade, and how no one had told them of Lynch’s “warning.” The asbestos workers “assumed that someone was looking after any health hazards there might be.”  Although no one delights in blaming the victim, Selikoff’s narrative was false.[21]

By the time Selikoff testified before the Senate subcommittee, he had been working with the asbestos workers’ union for at least eight years.  In 1957, before Selikoff’s collaboration began, the asbestos insulators’ union’s periodical, distributed to its members, noted that

“[t]he problem of hazardous materials was again discussed with the importance of using preventative measures to eliminate inhalation. It is suggested that, when working under dusty conditions, respirators should be used at all times and gloves whenever conditions warrant.”[22]

Later that same year, President Sickles, at the International Convention of the Asbestos Heat, Frost and Insulators Union, reported to his union’s delegates that he

“[b]eing well aware of the health hazards in the Asbestos industry, requested authority for the General Executive Board to make a study of the health hazards … that will enable the Board to adopt any policies that will tend to protect the health of our International membership.”[23]

In 1961, before the asbestos workers formally engaged Selikoff to conduct any epidemiologic study, the union ran a full page warning in its monthly magazine. The warning featured a picture of the grim reaper urging insulators to “Wear Your Respirator.”[24] Notwithstanding widespread warnings from union leaders, Selikoff and his staff, and manufacturers’ product label warnings, Selikoff acknowledged, in 1967, that more than nine out of 10 insulators failed to wear respirators on dusty jobs.[25]

Valorization of Johns Manville Corporation

Up until Sabourin’s appearance at Selikoff’s side in the Senate hearings, Johns Manville had ducked adverse verdicts in civil litigation.[26] Sabourin was eager to please, and Selikoff was happy to show up with industry support. For sitting through Selikoff’s hyperbolic testimony, distorted statistics, and fanciful history, and for helping finance Selikoff research, Sabourin was rewarded with some sops from Selikoff. After being skewered by Paul Brodeur and others, executives at Johns Manville were no doubt pleased to have Selikoff testify that “it is idle and probably incorrect to blame the industry.”[27]

Selikoff claimed that

“it has been inspiring to me as a medical scientist to see the responsibility with which at least one large company, Johns Manville, has approached this problem. They have had the advantage of the leadership of a rather remarkable man, Mr. Clinton Burnett. They have cooperated fully. They have held nothing back because they are determined to make asbestos safe to use and to work with.”[28]

Selikoff’s allies at the tort bar would soon descend upon Johns Manville with a vengeance, with no benefit of clergy or Selikoff’s blessings.


[1] Occupational Safety and Health Act of 1970, S. 2193 and S. 2788, Before the Subcomm. on Labor & Public Welfare, 91st Cong. at 1072 (May 5, 1970) (testimony of Irving Selikoff) [cited below as Selikoff OSHA testimony].

[2] Anonymous, Irving J. Selikoff, MD, 1915-1992: A Centennial Celebration, ICAHN ARCH. (Oct. 22, 2015), at https://archives.icahn.mssm.edu/irving-j-selikoff-md-1915-1992-a-centennial-celebration/; Sheldon W. Samuels, Knut Ringen, William N. Rom, Arthur Frank, Selikoff was a brave pioneer examining workers throughout the country, Ethical thinking in occupational and environmental medicine: Commentaries from the Selikoff Fund for Occupational and Environmental Cancer Research, 65 AM. J. INDUS. MED. 286 (2022); Judson MacLaury, The Job Safety Law of 1970: Its Passage Was Perilous, 104 MONTHLY LAB. REV. 18 (Mar. 1981) (Buried in the battle of witnesses for and against the Nixon proposal were some thought-provoking comments by Irving Selikoff. He described the suffering of construction workers who succumbed to asbestosis from applying asbestos insulation to buildings. Refusing to blame any one group, he asked rhetorically, “Who killed Cock Robin?” Selikoff’s answer was: “No one …. His has been an impersonal, technological death …. We have all failed.”).

[3] International Association of Heat and Frost Insulators and Asbestos Workers. Albert Hutchinson was president of the International; Andrew Haas was treasurer.

[4] Restatement (Second) of Torts § 402A (Am. Law Inst. 1965).

[5] Paul Brodeur, The Magic Mineral, NEW YORKER (Oct. 5, 1968), at https://www.newyorker.com/magazine/1968/10/12/the-magic-mineral.

[6] Selikoff OSHA testimony at 1077.

[7] Selikoff OSHA testimony at 1077.

[8][8] Selikoff OSHA testimony at 1078-79.

[9] Selikoff OSHA testimony at 1076.

[10] Irving J. Selikoff, Jacob Churg & E. Cuyler Hammond, Asbestos Exposure and Neoplasia, 188 J. AM. MED. ASS’N 22 (1964).

[11] Paul J. Villeneuve & Yang Mao, Lifetime probability of developing lung cancer, by smoking status, Canada, 85 CAN. J. PUB. HEALTH 358 (1994).

[12] Selikoff at 1074.

[13] Kenneth M. Lynch & W. Atmar Smith, Pulmonary Asbestosis III: Carcinoma of Lung in Asbesto-Silicosis, 24 AM. J. CANCER 56 (1935).

[14] Selikoff at 1080.

[15] Selikoff OSHA testimony at 1080.

[16] Selikoff OSHA testimony at 1074.

[17] Jeffrey E. Harris, Cigarette smoking among successive birth cohorts of men and women in the United States during 1900-80, 71. J. NAT’L CANCER INSTIT. 473 (1983).

[18] Irving J. Selikoff, Address to the delegates of the twenty-first convention of the International Association of Heat and Frost Insulators and Asbestos Workers at 9 (Chicago, Illinois, Sept. 1967), https://search.worldcat.org/fr/title/dr-irving-j-selikoffs-address-to-the-delegates-of-the-twenty-first-convention-of-the-international-association-of-heat-and-frost-insulators-and-asbestos-workers-chicago-illinois-september-1967/oclc/12288308.

[19] See Colin Talley, et al., Lung Cancer, Chronic Disease Epidemiology, and Medicine, 1948 – 1964, 59 J. HIST. MED. & ALLIED SCI. 329 (2004).

[20] Herbert K. Abrams, Cancer in Industry, Illinois ST. FED. LABOR WEEKLY NEWS LTR 1 (1955); Herbert K. Abrams, Cancer in Industry, 69 THE PAINTER & DECORATOR 15 (Mar. 1955). Abrams was the medical director of the Building Service Employees Union.

[21] Selikoff OSHA testimony at 1080.

[22] Asbestos Worker (July 1957).

[23] The Asbestos Worker at 1 (Oct, 1957) (reporting on the Asbestos Workers’ 19th General Convention).

[24] 15 The Asbestos Worker at 29 (Nov. 1961). The warning was developed under the guidance of C. V. Krieger of Local No. 28, Safety Superintendent at the Long Beach Naval Shipyard.

[25] Irving J. Selikoff, Address to the delegates of the twenty-first convention of the International Association of Heat and Frost Insulators and Asbestos Workers at 8, 9-10, 24 (Chicago, Illinois, Sept. 1967), at https://search.worldcat.org/fr/title/dr-irving-j-selikoffs-address-to-the-delegates-of-the-twenty-first-convention-of-the-international-association-of-heat-and-frost-insulators-and-asbestos-workers-chicago-illinois-september-1967/oclc/12288308

[26] Johns Mansville won a jury trial in 1969, but it would go on to lose in a case brought by insulator Clarence Borel, in 1971.

[27] Selikoff OSHA testimony at 1076.

[28] Selikoff OSHA testimony at 1078.

The 4th Reference Manual’s Treatment of Genetic Causes of Disease

January 23rd, 2026

After checking to see whether the new Reference Manual on Scientific Evidence[1] attended to some long overdue corrections, I turned my attention to the substance of the chapter on epidemiology. A cursory comparison between the third[2] and fourth[3] editions of the epidemiology chapter in the Reference Manual a lot of carry over from the third edition, some change in authorship, and at least one interesting change.

The two lawyer authors, Steve Gold and Michael Green, remain, but the authors with reasonable pretense to subject-matter expertise have changed. Gold and Green are both law professors with a long history of commenting on American tort and evidence law. Both are aligned with the lawsuit industry. Previous epidemiology authors, Daryl Michal Freedman and Leon Gordis are now gone from the chapter. Leon Gordis, who had been a chairman of the department of epidemiology, in the Bloomberg School of Public Health, Johns Hopkins University, died in September 2015, after the third edition was published. Daryl Michal Freedman, who been the other subject-matter expert on the third edition’s chapter on epidemiology, has been an epidemiologist with the Biostatistics Branch of the National Cancer Institute, for many years. It is not clear why he left the project.

Replacing Gordis and Freedman are Jonathan Chevrier and Brenda Eskenazi. Chevrier is an associate professor on the faculty of medicine, in the department of epidemiology, in McGill University. The focus of his work is on “common environmental contaminants,” and the role in the development and health of children. Brenda Eskenazi is professor emerita, in the University of California Berkeley School of Public Health, where she is the Director of the Center for Environmental Research and Children’s Health. Eskenazi is a member of a dodgy group known as the Collegium Ramazzini, which was responsible for staging an ex parte presentation of plaintiffs’ expert witnesses to judges presiding in asbestos litigation.[4] Eskenazi was not, however, a member of the Collegium at the time the group conspired with the late Irving Selikoff to pervert the course of justice in American asbestos litigation.

The second significant change is substantive; the fourth edition has added a new subsection to the epidemiology chapter. Comparing the texts of the third and fourth editions of this chapter reveals a new subheading in the new edition:[5]

Genetic and Molecular Epidemiologic Studies

Alas, there is not as much substance to the new subsection, which is less than four pages. Lawyers in the trenches might well have hoped for more substantive treatment of genetic epidemiology, and genetic causation. The chapter’s authors explain their abbreviated treatment with the comment:

“Although commentators have long forecast that the output of genetic and molecular epidemiology would revolutionize causal proof, as of this writing few judicial opinions have addressed these types of studies, and it is far from clear that a revolution is in the offing.”[6] 

The chapter authors are correct that some authors in the past proffered unrealistic predictions of how genetics would supplant correlational studies. Nonetheless, this area has not been as quiescent as the authors’ parsimonious treatment would suggest.

On the question of how prevalent are genetic causation issues, whether raised by plaintiffs or defendants, the chapter might have benefitted from the contributions of a practicing lawyer. Genetic issues come up with some frequency in the litigation of cases involving mesothelioma. The days of plaintiffs who had 30 years of amphibole asbestos exposure in the workplace are largely over. Today’s cases involve little to no exposure, and it stands to reason that the origins of the recently diagnosed cases are different from those diagnosed in the 1970s and 1980s.[7] Genetic cause of mesothelioma is a salient current issue that is passed over in this new Reference Manual.

The authors acknowledge a single birth defects case in which genetic causation was litigated,[8] which was already old news when the last edition of the Manual was published. There are now many more reported cases that cry out for discussion in this under-covered area of the Manual.[9] There are also many cases not reported that have turned on genetic issues. For instance, in some cancer and birth defect cases, the existence of a highly penetrant genetic mutation that could explain the occurrence of a disease completely raises a serious question whether the plaintiff who fails to test for the mutation can possibly have carried his burden of proof.[10] And then there are myriad cases in which the parties have engaged in motion practice, sometimes extended, over access to genetic testing materials.

Genetic issues have arisen in the litigation of high-profile general causation disputes. For instance, the failure to control for genetic effects in epidemiologic studies was a significant issue in the acetaminophen-autism litigation, with both sides presenting geneticists to explain whether the relevant studies were undermined by failure to control for genetic effects.[11]

In the Manual’s epidemiology chapter’s new section on genetics, the authors describe some basic terms and explain that genetic epidemiology may provide evidence for, or against, claims of health effects. The authors’ views come through most clearly in the following short passage:

“Alternatively, genetic epidemiology may reveal associations between genetic variations and a plaintiff’s disease, raising the issue of whether or not a genetic variation may be a competing cause of the disease. This requires assessment of whether the gene–disease association is causal in a general sense, whether it acts independently of the exposure, and whether it is a competing cause in the plaintiff’s specific instance. The extreme, though not typical, example would be a health outcome or disease entirely determined by genetics, 55 as is the case with sickle cell anemia.56[12]

The authors never explain or defend their claim that cases involving diseases caused entirely by genetics are “extreme” and “not typical.” At several points, the authors emphasize that gene-environment interactions are the more prevalent determinants of diseases.[13] If we were to catalog the currently known genetic determinants of diseases, the authors may be correct on a percentage basis, but the issue in any given case is whether the disease or harm claimed by the plaintiff is one of the “extreme” cases of complete genetic causation, or an instance of genetic susceptibility. The authors’ generalization, even if it were correct, would not be very helpful or informative for any specific case.

Perhaps even more important for lawyers, there is a substantive issue on which the new chapter manages to provide confusing guidance. The epidemiology chapter appears to create a false dichotomy between rare, highly penetrant genetic mutations that are uncommon causes of certain diseases, and the more prevalent genetic mutations and polymorphisms that leave persons more susceptible to the deleterious effects of exogenous exposures to toxic chemicals.[14] There is, however, another scenario omitted in the chapter’s discussion of genetic causation. Genetic mutations and polymorphisms may leave persons susceptible to normal, endogenous chemicals, stochastic cellular events, and biological processes that result in diseases such as cancers. In other words, the knee-jerk reflex to invoke exogenous, external toxic chemical exposures promotes a false dichotomy and obscures the obvious implication that susceptibility mutations and polymorphisms may lead to cancer without environmental exposures to harmful chemicals.[15]

The number of endogenous events leading to DNA alterations is enormous, and requires us to rethink the mantra that attributes chronic diseases to gene-environment interaction. At the very least, we need to stop thinking of “environment” as chemical exposures from without ourselves. The epidemiology chapter authors, like many writers, point to external chemical exposures as the culprits in gene-environment reactions, but they ignore the normal, endogenous events that lead to DNA damage, for which genetic susceptibility may be relevant. Mutations that result in increased susceptibility to cancer may affect DNA alterations from both endogenous and metabolic factors as well as from exposures to external chemicals.

Ignorance is never a good thing, and the chapter does the bar and bench a disservice in not adequately exploring genetic susceptibility in view of both exogenous and endogenous exposures that may be responsible for chronic diseases, such as cancers.


[1] National Academies of Sciences, Engineering, and Medicine & Federal Judicial Center, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE (4th ed. 2025) (cited as RMSE 4th ed.)

[2] Michael D. Green, D. Michal Freedman & Leon Gordis, Reference Guide on Epidemiology, 549, in RMSE 3rd ed.

[3] Steve C. Gold, Michael D. Green, Jonathan Chevrier, & Brenda Eskenazi, Reference Guide on Epidemiology, in RMSE 4th ed.

[4] See In re School Asbestos Litigation, 977 F.2d 764 (3d Cir. 1992). See also Cathleen M. Devlin, Disqualification of Federal Judges – Third Circuit Orders District Judge James McGirr Kelly to Disqualify Himself So As To Preserve ‘The Appearance of Justice’ Under 28 U.S.C. § 455 – In re School Asbestos Litigation (1992), 38 VILL. L. REV. 1219 (1993); Bruce A. Green, May Judges Attend Privately Funded Educational Programs? Should Judicial Education Be Privatized?:  Questions of Judicial Ethics and Policy, 29 FORDHAM URB. L. J. 941, 996-98 (2002).

[5] Steve Gold, et al., Reference Guide on Epidemiology, at 914, in RMSE 4th ed.

[6] Id. at 916.

[7] ToxicoGenomica, The Litigator’s Guide to Using Genomics in a Toxic Tort Case (2018).

[8] Id. at 917 & n.55 (citing Bowen v. E.I. Du Pont de Nemours & Co., No. CIV.A. 97C-06-194 CH, 2005 WL 1952859 (Del. Super. Ct. June 23, 2005), aff’d, 906 A.2d 787 (Del. 2006) (discussing the importance of a test for a genetic mutation, which was the defense’s alternative causation theory to plaintiff’s claim that a toxic exposure caused the birth defect at issue). The authors fail to mention that the Bowen case was actually dismissed.

[9] See, e.g., Oliver v. Sec’y Health & Human Servs., 900 F.3d 1357 (Fed. Cir. 2018); Ortega v. United States, 2021 WL 4477896, 2021 U.S. Dist. LEXIS 188969 (N.D.Ill. Sept. 30, 2021); Vanslembrouck ex rel. Braverman v. Halperin, 2014 WL 5462596 (Mich. App. 2014).

[10] See, e.g., Halter v. Boehringer Ingelheim Pharms. Inc., no. 2023-L-001382, Cir. Ct. Cook Cty., Illinois, jury verdict (Aug. 27, 2025) (defense verdict in colorectal cancer case in which plaintiff failed to test for genetic mutation); see also Lauraann Wood, Boehringer Wins Another Zantac Cancer Trial In Illinois, LAW360, Chicago (Aug. 27, 2025).

[11] See, e.g., In re Acetaminophen – ASD-ADHD Prods. Liab. Litig., 707 F.Supp.3d 309, 320  (S.D.N.Y. 2023).

[12] Id. at 916-17 (emphasis added).

[13] Id. at 915.

[14] See, e.g., id. at 967n.190, citing McMillan v. Dep’t of Veterans Affairs, 294 F. Supp. 2d 305, 312 (E.D.N.Y. 2003) (“It is generally accepted that genetic susceptibility plays a key role in determining the adverse effects of environmental chemicals. . . . [I]f polymorphisms of the gene encoding the AhR [protein] exist in humans as they do in laboratory animals, some people would be at greater risk or at lesser risk for the toxic and carcinogenic effects of TCDD [dioxin].”).

[15] See Edward J. Calabrese, Changing the paradigm: The biggest polluter and threat to your health is your body, J. OCCUP. & ENVT’L HYG. (2025), published on-line, ahead of print.

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