TORTINI

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

Dodgy Data Duck Daubert Decisions

March 11th, 2020

Judges say the darndest things, especially when it comes to their gatekeeping responsibilities under Federal Rules of Evidence 702 and 703. One of the darndest things judges say is that they do not have to assess the quality of the data underlying an expert witness’s opinion.

Even when acknowledging their obligation to “assess the reasoning and methodology underlying the expert’s opinion, and determine whether it is both scientifically valid and applicable to a particular set of facts,”[1] judges have excused themselves from having to look at the trustworthiness of the underlying data for assessing the admissibility of an expert witness’s opinion.

In McCall v. Skyland Grain LLC, the defendant challenged an expert witness’s reliance upon oral reports of clients. The witness, Mr. Bradley Walker, asserted that he regularly relied upon such reports, in similar contexts of the allegations that the defendant misapplied herbicide to plaintiffs’ crops. The trial court ruled that the defendant could cross-examine the declarant who was available trial, and concluded that the “reliability of that underlying data can be challenged in that manner and goes to the weight to be afforded Mr. Walker’s conclusions, not their admissibility.”[2] Remarkably, the district court never evaluated the reasonableness of Mr. Walker’s reliance upon client reports in this or any context.

In another federal district court case, Rodgers v. Beechcraft Corporation, the trial judge explicitly acknowledged the responsibility to assess whether the expert witness’s opinion was based upon “sufficient facts and data,” but disclaimed any obligation to assess the quality of the underlying data.[3] The trial court in Rodgers cited a Tenth Circuit case from 2005,[4] which in turn cited the Supreme Court’s 1993 decision in Daubert, for the proposition that the admissibility review of an expert witness’s opinion was limited to a quantitative sufficiency analysis, and precluded a qualitative analysis of the underlying data’s reliability. Quoting from another district court criminal case, the court in Rodgers announced that “the Court does not examine whether the facts obtained by the witness are themselves reliable – whether the facts used are qualitatively reliable is a question of the weight to be given the opinion by the factfinder, not the admissibility of the opinion.”[5]

In a 2016 decision, United States v. DishNetwork LLC, the court explicitly disclaimed that it was required to “evaluate the quality of the underlying data or the quality of the expert’s conclusions.”[6] This district court pointed to a Seventh Circuit decision, which maintained that  “[t]he soundness of the factual underpinnings of the expert’s analysis and the correctness of the expert’s conclusions based on that analysis are factual matters to be determined by the trier of fact, or, where appropriate, on summary judgment.”[7] The Seventh Circuit’s decision, however, issued in June 2000, several months before the effective date of the amendments to Federal Rule of Evidence 702 (December 2000).

In 2012, a magistrate judge issued an opinion along the same lines, in Bixby v. KBR, Inc.[8] After acknowledging what must be done in ruling on a challenge to an expert witness, the judge took joy in what could be overlooked. If the facts or data upon which the expert witness has relied are “minimally sufficient,” then the gatekeeper can regard questions about “the nature or quality of the underlying data bear upon the weight to which the opinion is entitled or to the credibility of the expert’s opinion, and do not bear upon the question of admissibility.”[9]

There need not be any common law mysticism to the governing standard. The relevant law is, of course, a statute, which appears to be forgotten in many of the failed gatekeeping decisions:

Rule 702. Testimony by Expert Witnesses

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;

(b) the testimony is based on sufficient facts or data;

(c) the testimony is the product of reliable principles and methods; and

(d) the expert has reliably applied the principles and methods to the facts of the case.

It would seem that you could not produce testimony that is the product of reliable principles and methods by starting with unreliable underlying facts and data. Certainly, having a reliable method would require selecting reliable facts and data from which to start. What good would the reliable application of reliable principles to crummy data?

The Advisory Committee Notes to Rule 702 hints at an answer to the problem:

“There has been some confusion over the relationship between Rules 702 and 703. The amendment makes clear that the sufficiency of the basis of an expert’s testimony is to be decided under Rule 702. Rule 702 sets forth the overarching requirement of reliability, and an analysis of the sufficiency of the expert’s basis cannot be divorced from the ultimate reliability of the expert’s opinion. In contrast, the ‘reasonable reliance’ requirement of Rule 703 is a relatively narrow inquiry. When an expert relies on inadmissible information, Rule 703 requires the trial court to determine whether that information is of a type reasonably relied on by other experts in the field. If so, the expert can rely on the information in reaching an opinion. However, the question whether the expert is relying on a sufficient basis of information—whether admissible information or not—is governed by the requirements of Rule 702.”

The answer is only partially satisfactory. First, if the underlying data are independently admissible, then there may indeed be no gatekeeping of an expert witness’s reliance upon such data. Rule 703 imposes a reasonableness test for reliance upon inadmissible underlying facts and data, but appears to give otherwise admissible facts and data a pass. Second, the above judicial decisions do not mention any Rule 703 challenge to the expert witnesses’ reliance. If so, then there is a clear lesson for counsel. When framing a challenge to the admissibility of an expert witness’s opinion, show that the witness has unreasonably relied upon facts and data, from whatever source, in violation of Rule 703. Then show that without the unreasonably relied upon facts and data, the witness cannot show that his or her opinion satisfies Rule 702(a)-(d).


[1]  See, e.g., McCall v. Skyland Grain LLC, Case 1:08-cv-01128-KHV-BNB, Order (D. Colo. June 22, 2010) (Brimmer, J.) (citing Dodge v. Cotter Corp., 328 F.3d 1212, 1221 (10th Cir. 2003), citing in turn Daubert v. Merrill Dow Pharms., Inc., 509 U.S. 579,  592-93 (1993).

[2]  McCall v. Skyland Grain LLC Case 1:08-cv-01128-KHV-BNB, Order at p.9 n.6 (D. Colo. June 22, 2010) (Brimmer, J.)

[3]  Rodgers v. Beechcraft Corp., Case No. 15-CV-129-CVE-PJC, Report & Recommendation at p.6 (N.D. Okla. Nov. 29, 2016).

[4]  Id., citing United.States. v. Lauder, 409 F.3d 1254, 1264 (10th Cir. 2005) (“By its terms, the Daubert opinion applies only to the qualifications of an expert and the methodology or reasoning used to render an expert opinion” and “generally does not, however, regulate the underlying facts or data that an expert relies on when forming her opinion.”), citing Daubert v. Merrill Dow Pharms., Inc., 509 U.S. 579, 592-93 (1993).

[5]  Id., citing and quoting United States v. Crabbe, 556 F. Supp. 2d 1217, 1223
(D. Colo. 2008) (emphasis in original). In Crabbe, the district judge mostly excluded the challenged expert witness, thus rendering its verbiage on quality of data as obiter dicta). The pronouncements about the nature of gatekeeping proved harmless error when the court dismissed the case on other grounds. Rodgers v. Beechcraft Corp., 248 F. Supp. 3d 1158 (N.D. Okla. 2017) (granting summary judgment).

[6]  United States v. DishNetwork LLC, No. 09-3073, Slip op. at 4-5 (C.D. Ill. Jan. 13, 2016) (Myerscough, J.)

[7]  Smith v. Ford Motor Co., 215 F.3d 713, 718 (7th Cir. 2000).

[8]  Bixby v. KBR, Inc., Case 3:09-cv-00632-PK, Slip op. at 6-7 (D. Ore. Aug. 29, 2012) (Papak, M.J.)

[9]  Id. (citing Hangarter v. Provident Life & Accident Ins. Co., 373 F.3d 998, 1017 (9th Cir. 2004), quoting Children’s Broad Corp. v. Walt Disney Co., 357 F.3d 860, 865 (8th Cir. 2004) (“The factual basis of an expert opinion goes to the credibility of the testimony, not the admissibility, and it is up to the opposing party to examine the factual basis for the opinion in cross-examination.”).

Science Journalism – UnDark Noir

February 23rd, 2020

Critics of the National Association of Scholars’ conference on Fixing Science pointed readers to an article in Undark, an on-line popular science site for lay audiences, and they touted the site for its science journalism. My review of the particular article left me unimpressed and suspicious of Undark’s darker side. When I saw that the site featured an article on the history of the Supreme Court’s Daubert decision, I decided to give the site another try. For one thing, I am sympathetic to the task science journalists take on: it is important and difficult. In many ways, lawyers must commit to perform the same task. Sadly, most journalists and lawyers, with some notable exceptions, lack the scientific acumen and English communication skills to meet the needs of this task.

The Undark article that caught my attention was a history of the Daubert decision and the Bendectin litigation that gave rise to the Supreme Court case.[1] The author, Peter Andrey Smith, is a freelance reporter, who often covers science issues. In his Undark piece, Smith covered some of the oft-told history of the Daubert case, which has been told before, better and in more detail in many legal sources. Smith gets some credit for giving the correct pronunciation of the plaintiff’s name – “DAW-burt,” and for recounting how both sides declared victory after the Supreme Court’s ruling. The explanation Smith gives of the opinion by Associate Justice Harry Blackmun is reasonably accurate, and he correctly notes that a partial dissenting opinion by Chief Justice Rehnquist complained that the majority’s decision would have trial judges become “amateur scientists.” Nowhere in the article will you find, however, the counter to the dissent: an honest assessment of the institutional and individual competence of juries to decide complex scientific issues.

The author’s biases eventually, however, become obvious. He recounts his interviews with Jason Daubert and his mother, Joyce Daubert. He earnestly reports how Joyce Daubert remembered having taken Bendectin during her pregnancy with Jason, and in the moment of that recall, “she felt she’d finally identified the teratogen that harmed Jason.” Really? Is that how teratogens are identified? Might it have been useful and relevant for a scientific journalist to explain that there are four million live births every year in the United States and that 3% of children born each year have major congenital malformations? And that most malformations have no known cause? Smith ingenuously relays that Jason Daubert had genetic testing, but omits that genetic testing in the early 1990s was fairly primitive and limited. In any event, how were any expert witnesses supposed to rule out base-line risk of birth defects, especially given weak to non-existent epidemiologic support for the Daubert’s claims? Smith does answer these questions; he does not even acknowledge the questions.

Smith later quotes Joyce Daubert as describing the litigation she signed up for as “the hill I’ll die on. You only go to war when you think you can win.” Without comment or analysis, Smith gives Joyce Daubert an opportunity to rant against the “injustice” of how her lawsuit turned out. Smith tells us that the Dauberts found the “legal system remains profoundly disillusioning.” Joyce Daubert told Smith that “it makes me feel stupid that I was so naïve to think that, after we’d invested so much in the case, that we would get justice.”  When called for jury duty, she introduces herself as

“I’m Daubert of Daubert versus Merrell Dow … ; I don’t want to sit on this jury and pretend that I can pass judgment on somebody when there is no justice. Please allow me to be excused.”

But didn’t she really get all the justice she deserved? Given her zealotry, doesn’t she deserve to have her name on the decision that serves to rein in expert witnesses who outrun their scientific headlights? Smith is coy and does not say, but in presenting Mrs. Daubert’s rant, without presenting the other side, he is using his journalistic tools in a fairly blatant attempt to mislead. At this point, I begin to get the feeling that Smith is preaching to a like-minded choir over there at Undark.

The reader is not treated to any interviews with anyone from the company that made Bendectin, any of its scientists, or any of the scientists who published actual studies on whether Bendectin was associated with the particular birth defects Jason Daubert had, or for that matter, with any birth defects at all. The plaintiffs’ expert witnesses quoted and cited never published anything at all on the subject. The readers are left to their imagination about how the people who developed Bendectin felt about the litigation strategies and tactics of the lawsuit industry.

The journalistic ruse is continued with Smith’s treatment of the other actors in the Daubert passion play. Smith describes the Bendectin plaintiffs’ lawyer Barry Nace in hagiographic terms, but omits his bar disciplinary proceedings.[2] Smith tells us that Nace had an impressive background in chemistry, and quotes him in an interview in which he described the evidentiary rules on scientific witness testimony as “scientific evidence crap.”

Smith never describes the Daubert’s actual affirmative evidence in any detail, which one might expect in a sophisticated journalistic outlet. Instead, he described some of their expert witnesses, Shanna Swan, a reproductive epidemiologist, and Alan K. Done, “a former pediatrician from Wayne State University.” Smith is secretive about why Done was done in at Wayne State; and we learn nothing about the serious accusations of perjury on credentials by Done. Instead, Smith regales us with Done’s tsumish theory, which takes inconclusive bits of evidence, throws them together, and then declares causation that somehow eludes the rest of the scientific establishment.

Smith tells us that Swan was a rebuttal witness, who gave an opinion that the data did not rule out “the possibility Bendectin caused defects.” Legally and scientifically, Smith is derelict in failing to explain that the burden was on the party claiming causation, and that Swan’s efforts to manufacture doubt were beside the point. Merrell Dow did not have to rule out any possibility of causation; the plaintiffs had to establish causation. Nor does Smith delve into how Swan sought to reprise her performance in the silicone gel breast implant litigation, only to be booted by several judges as an expert witness. And then for a convincer, Smith sympathetically repeats plaintiffs’ lawyer Barry Nace’s hyperbolic claim that Bendectin manufacturer, Merrell Dow had been “financing scientific articles to get their way,” adding by way of emphasis, in his own voice:

“In some ways, here was the fake news of its time: If you lacked any compelling scientific support for your case, one way to undermine the credibility of your opponents was by calling their evidence ‘junk science’.”

Against Nace’s scatalogical Jackson Pollack approach, Smith is silent about another plaintiffs’ expert witness, William McBride, who was found guilty of scientific fraud.[3] Smith reports interviews of several well-known, well-respected evidence scholars. He dutifully report Professor Edward Cheng’s view that “the courts were right to dismiss the [Bendectin] plaintiffs’ claims.” Smith quotes Professor D. Michael Risinger that claims from both sides in Bendectin cases were exaggerated, and that the 1970s and 1980s saw an “unbridled expansion of self-anointed experts,” with “causation in toxic torts had been allowed to become extremely lax.” So a critical reader might wonder why someone like Professor Cheng, who has a doctorate in statistics, a law degree from Harvard, and teaches at Vanderbilt Law School, would vindicate the manufacturers’ position in the Bendectin litigation. Smith never attempts to reconcile his interviews of the law professors with the emotive comments of Barry Nace and Joyce Daubert.

Smith acknowledges that a reformulated version of Bendectin, known as  Diclegis, was approved by the Food and Drug Administration in the United States, in 2013, for treatment of  nausea and vomiting during pregnancy. Smith tells us that Joyce is not convinced the drug should be back on the market,” but really why would any reasonable person care about her view of the matter? The challenge by Nav Persaud, a Toronto physician, is cited, but Persaud’s challenge is to the claim of efficacy, not to the safety of the medication. Smith tells us that Jason Daubert “briefly mulled reopening his case when Diclegis, the updated version of Bendectin, was re-approved.” But how would the approval of Diclegis, on the strength of a full new drug application, somehow support his claim anew? And how would he “reopen” a claim that had been fully litigated in the 1990s, and well past any statute of limitations?

Is this straight reporting? I think not. It is manipulative and misleading.

Smith notes, without attribution, that some scholars condemn litigation, such as the cases involving Bendectin, as an illegitimate form of regulation of medications. In opposition, he appears to rely upon Elizabeth Chamblee Burch, a professor at the University of Georgia School of Law for the view that because the initial pivotal clinical trials for regulatory approvals take place in limited populations, litigation “serves as a stopgap for identifying rare adverse outcomes that could crop up when several hundreds of millions of people are exposed to those products over longer periods of time.” The problem with this view is that Smith ignores the whole process of pharmacovigilance, post-registration trials, and pharmaco-epidemiologic studies conducted after the licensing of a new medication. The suggested necessity of reliance upon the litigation system as an adjunct to regulatory approval is at best misplaced and tenuous.

Smith correctly explains that the Daubert standard is still resisted in criminal cases, where it could much improve the gatekeeping of forensic expert witness opinion. But while the author gets his knickers in a knot over wrongful convictions, he seems quite indifferent to wrongful judgments in civil action.

Perhaps the one positive aspect of this journalistic account of the Daubert case was that Jason Daubert, unlike his mother, was open minded about his role in transforming the law of scientific evidence. According to Smith, Jason Daubert did not see the case as having “not ruined his life.” Indeed, Jason seemed to approve the basic principle of the Daubert case, and the subsequent legislation that refined the admissibility standard: “Good science should be all that gets into the courts.”


[1] Peter Andrey Smith, “Where Science Enters the Courtroom, the Daubert Name Looms Large: Decades ago, two parents sued a drug company over their newborn’s deformity – and changed courtroom science forever,” Undark (Feb. 17, 2020).

[2]  Lawyer Disciplinary Board v. Nace, 753 S.E.2d 618, 621–22 (W. Va.) (per curiam), cert. denied, 134 S. Ct. 474 (2013).

[3] Neil Genzlinger, “William McBride, Who Warned About Thalidomide, Dies at 91,” N.Y. Times (July 15, 2018); Leigh Dayton, “Thalidomide hero found guilty of scientific fraud,” New Scientist (Feb. 27, 1993); G.F. Humphrey, “Scientific fraud: the McBride case,” 32 Med. Sci. Law 199 (1992); Andrew Skolnick, “Key Witness Against Morning Sickness Drug Faces Scientific Fraud Charges,” 263 J. Am. Med. Ass’n 1468 (1990).

Science Bench Book for Judges

July 13th, 2019

On July 1st of this year, the National Judicial College and the Justice Speakers Institute, LLC released an online publication of the Science Bench Book for Judges [Bench Book]. The Bench Book sets out to cover much of the substantive material already covered by the Federal Judicial Center’s Reference Manual:

Acknowledgments

Table of Contents

  1. Introduction: Why This Bench Book?
  2. What is Science?
  3. Scientific Evidence
  4. Introduction to Research Terminology and Concepts
  5. Pre-Trial Civil
  6. Pre-trial Criminal
  7. Trial
  8. Juvenile Court
  9. The Expert Witness
  10. Evidence-Based Sentencing
  11. Post Sentencing Supervision
  12. Civil Post Trial Proceedings
  13. Conclusion: Judges—The Gatekeepers of Scientific Evidence

Appendix 1 – Frye/Daubert—State-by-State

Appendix 2 – Sample Orders for Criminal Discovery

Appendix 3 – Biographies

The Bench Book gives some good advice in very general terms about the need to consider study validity,[1] and to approach scientific evidence with care and “healthy skepticism.”[2] When the Bench Book attempts to instruct on what it represents the scientific method of hypothesis testing, the good advice unravels:

“A scientific hypothesis simply cannot be proved. Statisticians attempt to solve this dilemma by adopting an alternate [sic] hypothesis – the null hypothesis. The null hypothesis is the opposite of the scientific hypothesis. It assumes that the scientific hypothesis is not true. The researcher conducts a statistical analysis of the study data to see if the null hypothesis can be rejected. If the null hypothesis is found to be untrue, the data support the scientific hypothesis as true.”[3]

Even in experimental settings, a statistical analysis of the data do not lead to a conclusion that the null hypothesis is untrue, as opposed to not reasonably compatible with the study’s data. In observational studies, the statistical analysis must acknowledge whether and to what extent the study has excluded bias and confounding. When the Bench Book turns to speak of statistical significance, more trouble ensues:

“The goal of an experiment, or observational study, is to achieve results that are statistically significant; that is, not occurring by chance.”[4]

In the world of result-oriented science, and scientific advocacy, it is perhaps true that scientists seek to achieve statistically significant results. Still, it seems crass to come right out and say so, as opposed to saying that the scientists are querying the data to see whether they are compatible with the null hypothesis. This first pass at statistical significance is only mildly astray compared with the Bench Book’s more serious attempts to define statistical significance and confidence intervals:

4.10 Statistical Significance

The research field agrees that study outcomes must demonstrate they are not the result of random chance. Leaving room for an error of .05, the study must achieve a 95% level of confidence that the results were the product of the study. This is denoted as p ≤ 05. (or .01 or .1).”[5]

and

“The confidence interval is also a way to gauge the reliability of an estimate. The confidence interval predicts the parameters within which a sample value will fall. It looks at the distance from the mean a value will fall, and is measured by using standard deviations. For example, if all values fall within 2 standard deviations from the mean, about 95% of the values will be within that range.”[6]

Of course, the interval speaks to the precision of the estimate, not its reliability, but that is a small point. These definitions are virtually guaranteed to confuse judges into conflating statistical significance and the coefficient of confidence with the legal burden of proof probability.

The Bench Book runs into problems in interpreting legal decisions, which would seem softer grist for the judicial mill. The authors present dictum from the Daubert decision as though it were a holding:[7]

“As noted in Daubert, ‘[t]he focus, of course, must be solely on principles and methodology, not on the conclusions they generate’.”

The authors fail to mention that this dictum was abandoned in Joiner, and that it is specifically rejected by statute, in the 2000 revision to the Federal Rule of Evidence 702.

Early in the Bench Book, it authors present a subsection entitled “The Myth of Scientific Objectivity,” which they might have borrowed from Feyerabend or Derrida. The heading appears misleading because the text contradicts it:

“Scientists often develop emotional attachments to their work—it can be difficult to abandon an idea. Regardless of bias, the strongest intellectual argument, based on accepted scientific hypotheses, will always prevail, but the road to that conclusion may be fraught with scholarly cul-de-sacs.”[8]

In a similar vein, the authors misleadingly tell readers that “the forefront of science is rarely encountered in court,” and so “much of the science mentioned there shall be considered established….”[9] Of course, the reality is that many causal claims presented in court have already been rejected or held to be indeterminate by the scientific community. And just when readers may think themselves safe from the goblins of nihilism, the authors launch into a theory of naïve probabilism that science is just placing subjective probabilities upon data, based upon preconceived biases and beliefs:

“All of these biases and beliefs play into the process of weighing data, a critical aspect of science. Placing weight on a result is the process of assigning a probability to an outcome. Everything in the universe can be expressed in probabilities.”[10]

So help the expert witness who honestly (and correctly) testifies that the causal claim or its rejection cannot be expressed as a probability statement!

Although I have not read all of the Bench Book closely, there appears to be no meaningful discussion of Rule 703, or of the need to access underlying data to ensure that the proffered scientific opinion under scrutiny has used appropriate methodologies at every step in its development. Even a 412 text cannot address every issue, but this one does little to help the judicial reader find more in-depth help on statistical and scientific methodological issues that arise in occupational and environmental disease claims, and in pharmaceutical products litigation.

The organizations involved in this Bench Book appear to be honest brokers of remedial education for judges. The writing of this Bench Book was funded by the State Justice Institute (SJI) Which is a creation of federal legislation enacted with the laudatory goal of improving the quality of judging in state courts.[11] Despite its provenance in federal legislation, the SJI is a a private, nonprofit corporation, governed by 11 directors appointed by the President, and confirmed by the Senate. A majority of the directors (six) are state court judges, one state court administrator, and four members of the public (no more than two from any one political party). The function of the SJI is to award grants to improve judging in state courts.

The National Judicial College (NJC) originated in the early 1960s, from the efforts of the American Bar Association, American Judicature Society and the Institute of Judicial Administration, to provide education for judges. In 1977, the NJC became a Nevada not-for-profit (501)(c)(3) educational corporation, which its campus at the University of Nevada, Reno, where judges could go for training and recreational activities.

The Justice Speakers Institute appears to be a for-profit company that provides educational resources for judge. A Press Release touts the Bench Book and follow-on webinars. Caveat emptor.

The rationale for this Bench Book is open to question. Unlike the Reference Manual for Scientific Evidence, which was co-produced by the Federal Judicial Center and the National Academies of Science, the Bench Book’s authors are lawyers and judges, without any subject-matter expertise. Unlike the Reference Manual, the Bench Book’s chapters have no scientist or statistician authors, and it shows. Remarkably, the Bench Book does not appear to cite to the Reference Manual or the Manual on Complex Litigation, at any point in its discussion of the federal law of expert witnesses or of scientific or statistical method. Perhaps taxpayers would have been spared substantial expense if state judges were simply encouraged to read the Reference Manual.


[1]  Bench Book at 190.

[2]  Bench Book at 174 (“Given the large amount of statistical information contained in expert reports, as well as in the daily lives of the general society, the ability to be a competent consumer of scientific reports is challenging. Effective critical review of scientific information requires vigilance, and some healthy skepticism.”).

[3]  Bench Book at 137; see also id. at 162.

[4]  Bench Book at 148.

[5]  Bench Book at 160.

[6]  Bench Book at 152.

[7]  Bench Book at 233, quoting Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 595 (1993).

[8]  Bench Book at 10.

[9]  Id. at 10.

[10]  Id. at 10.

[11] See State Justice Institute Act of 1984 (42 U.S.C. ch. 113, 42 U.S.C. § 10701 et seq.).

Daubert Retrospective – Statistical Significance

January 5th, 2019

The holiday break was an opportunity and an excuse to revisit the briefs filed in the Supreme Court by parties and amici, in the Daubert case. The 22 amicus briefs in particular provided a wonderful basis upon which to reflect how far we have come, and also how far we have to go, to achieve real evidence-based fact finding in technical and scientific litigation. Twenty-five years ago, Rules 702 and 703 vied for control over errant and improvident expert witness testimony. With Daubert decided, Rule 702 emerged as the winner. Sadly, most courts seem to ignore or forget about Rule 703, perhaps because of its awkward wording. Rule 702, however, received the judicial imprimatur to support the policing and gatekeeping of dysepistemic claims in the federal courts.

As noted last week,1 the petitioners (plaintiffs) in Daubert advanced several lines of fallacious and specious argument, some of which was lost in the shuffle and page limitations of the Supreme Court briefings. The plaintiffs’ transposition fallacy received barely a mention, although it did bring forth at least a footnote in an important and overlooked amicus brief filed by American Medical Association (AMA), the American College of Physicians, and over a dozen other medical specialty organizations,2 all of which both emphasized the importance of statistical significance in interpreting epidemiologic studies, and the fallacy of interpreting 95% confidence intervals as providing a measure of certainty about the estimated association as a parameter. The language of these associations’ amicus brief is noteworthy and still relevant to today’s controversies.

The AMA’s amicus brief, like the brief filed by the National Academies of Science and the American Association for the Advancement of Science, strongly endorsed a gatekeeping role for trial courts to exclude testimony not based upon rigorous scientific analysis:

The touchstone of Rule 702 is scientific knowledge. Under this Rule, expert scientific testimony must adhere to the recognized standards of good scientific methodology including rigorous analysis, accurate and statistically significant measurement, and reproducibility.”3

Having incorporated the term “scientific knowledge,” Rule 702 could not permit anything less in expert witness testimony, lest it pollute federal courtrooms across the land.

Elsewhere, the AMA elaborated upon its reference to “statistically significant measurement”:

Medical researchers acquire scientific knowledge through laboratory investigation, studies of animal models, human trials, and epidemiological studies. Such empirical investigations frequently demonstrate some correlation between the intervention studied and the hypothesized result. However, the demonstration of a correlation does not prove the hypothesized result and does not constitute scientific knowledge. In order to determine whether the observed correlation is indicative of a causal relationship, scientists necessarily rely on the concept of “statistical significance.” The requirement of statistical reliability, which tends to prove that the relationship is not merely the product of chance, is a fundamental and indispensable component of valid scientific methodology.”4

And then again, the AMA spelled out its position, in case the Court missed its other references to the importance of statistical significance:

Medical studies, whether clinical trials or epidemiologic studies, frequently demonstrate some correlation between the action studied … . To determine whether the observed correlation is not due to chance, medical scientists rely on the concept of ‘statistical significance’. A ‘statistically significant’ correlation is generally considered to be one in which statistical analysis suggests that the observed relationship is not the result of chance. A statistically significant correlation does not ‘prove’ causation, but in the absence of such a correlation, scientific causation clearly is not proven.95

In its footnote 9, in the above quoted section of the brief, the AMA called out the plaintiffs’ transposition fallacy, without specifically citing to plaintiffs’ briefs:

It is misleading to compare the 95% confidence level used in empirical research to the 51% level inherent in the preponderance of the evidence standard.”6

Actually the plaintiffs’ ruse was much worse than misleading. The plaintiffs did not compare the two probabilities; they equated them. Some might call this ruse, an outright fraud on the court. In any event, the AMA amicus brief remains an available, citable source for opposing this fraud and the casual dismissal of the importance of statistical significance.

One other amicus brief touched on the plaintiffs’ statistical shanigans. The Product Liability Advisory Council, National Association of Manufacturers, Business Roundtable, and Chemical Manufacturers Association jointly filed an amicus brief to challenge some of the excesses of the plaintiffs’ submissions.7  Plaintiffs’ expert witness, Shanna Swan, had calculated type II error rates and post-hoc power for some selected epidemiologic studies relied upon by the defense. Swan’s complaint had been that some studies had only 20% probability (power) to detect a statistically significant doubling of limb reduction risk, with significance at p < 5%.8

The PLAC Brief pointed out that power calculations must assume an alternative hypothesis, and that the doubling of risk hypothesis had no basis in the evidentiary record. Although the PLAC complaint was correct, it missed the plaintiffs’ point that the defense had set exceeding a risk ratio of 2.0, as an important benchmark for specific causation attributability. Swan’s calculation of post-hoc power would have yielded an even lower probability for detecting risk ratios of 1.2 or so. More to the point, PLAC noted that other studies had much greater power, and that collectively, all the available studies would have had much greater power to have at least one study achieve statistical significance without dodgy re-analyses.


1 The Advocates’ Errors in Daubert” (Dec. 28, 2018).

2 American Academy of Allergy and Immunology, American Academy of Dermatology, American Academy of Family Physicians, American Academy of Neurology, American Academy of Orthopaedic Surgeons, American Academy of Pain Medicine, American Association of Neurological Surgeons, American College of Obstetricians and Gynecologists, American College of Pain Medicine, American College of Physicians, American College of Radiology, American Society of Anesthesiologists, American Society of Plastic and Reconstructive Surgeons, American Urological Association, and College of American Pathologists.

3 Brief of the American Medical Association, et al., as Amici Curiae, in Support of Respondent, in Daubert v. Merrell Dow Pharmaceuticals, Inc., U.S. Supreme Court no. 92-102, 1993 WL 13006285, at *27 (U.S., Jan. 19, 1993)[AMA Brief].

4 AMA Brief at *4-*5 (emphasis added).

5 AMA Brief at *14-*15 (emphasis added).

6 AMA Brief at *15 & n.9.

7 Brief of the Product Liability Advisory Council, Inc., National Association of Manufacturers, Business Roundtable, and Chemical Manufacturers Association as Amici Curiae in Support of Respondent, as Amici Curiae, in Support of Respondent, in Daubert v. Merrell Dow Pharmaceuticals, Inc., U.S. Supreme Court no. 92-102, 1993 WL 13006288 (U.S., Jan. 19, 1993) [PLAC Brief].

8 PLAC Brief at *21.