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

Woodside & Davis on the Bradford Hill Considerations

August 23rd, 2013

Dr. Frank Woodside and Allison Davis have published an article on the so-called Bradford Hill criteria.  Frank C. Woodside, III & Allison G. Davis, “The Bradford Hill Criteria: The Forgotten Predicate,” 35 Thomas Jefferson L. Rev. 103 (2013).

Their short paper may be of interest to Rule 702 geeks, and students of how the law parses causal factors in litigation.

The authors argue that a “predicate” to applying the Hill criteria consists of:

  • ascertaining a clear-cut association,
  • determining the studies establishing the association are valid, and
  • satisfying the Daubert [1][sic] requirements.

Id. at 107.  Parties contending for a causal association often try to flyblow the need for statistical significance at any level, and argue that Bradford Hill did not insist upon statistical testing.  Woodside and Davis remind us that Bradford Hill was quite firm in insisting upon the need to rule out random variability as an explanation for an association:

“Our observations reveal an association between two variables, perfectly clear-cut and beyond what we would care to attribute to the play of chance.”

Id. at 105; see Hill, Austin Bradford Hill, “The Environment and Disease: Association or Causation?” 58 Proc. Royal Soc’y Med. 295 (1965).  The authors correctly note that the need for study validity is fairly implied by Bradford Hill’s casual expression about “perfectly clear-cut.”

Woodside and Davis appear to acquiesce in the plaintiffs’ tortured interpretation of Bradford Hill’s speech, on which statistical significance supposedly is unimportant.  Woodside & Davis at 105 & n.7 (suggesting that Bradford Hill “seemingly negates the second [the requirement of statistical significance] when he discounts the value of significance testing, citing Bradford Hill at 299).

Woodside and Davis, however, miss the heavy emphasis that Bradford Hill actually placed upon “tests of significance”:

“No formal tests of significance can answer those questions. Such tests can, and should, remind us of the effects that the play of chance can create, and they will instruct us in the likely magnitude of those effects. Beyond that they contribute nothing to the ‘proof’ of our hypothesis.”

Bradford Hill at 299.  Bradford Hill never says that statistical tests contribute nothing to proving an hypothesis; rather, his emphasis is on the insufficiency of statistical tests alone to establish causality.  Bradford Hill’s “beyond that” language clearly stakes out the preliminary, but necessary importance of ruling out the play of chance before proceeding to consider the causal factors.

Passing beyond their exegetical fumble, Woodside and Davis proceed to discuss the individual Bradford Hill considerations and how they have fared in the crucible of Rule 702.  Their discussion may be helpful to lawyers who want to track the individual considerations, and how they have treated, or dismissed, by trial courts charged with gatekeeping expert witness opinion testimony.

There is another serious problem in the Woodside and Davis paper.  The authors describe risk ratios and the notion of “confidence intervals”:

“A confidence interval provides both the relative risk found in the study and a range (interval) within which the risk would likely fall if the study were repeated numerous times.32 … As such, risk measures used in conjunction with confidence intervals are critical in establishing a perfectly clear-cut association when it comes to examining the results of a single study.35

Woodside & Davis at 110.  The authors cite to the Reference Manual on Scientific Evidence (3d 2011), but they fail to catch important nuances of the definition of a confidence interval.  The obtained interval from a given study is not the interval within which the “risk would likely fall if the study were repeated… .”  Rather it is 95% of the many intervals, from the many repeated studies done on the same population, with the same sample size, which would capture the true risk.  As for the obtained interval, the true risk is either within it, or not, and no probability value attaches to the likelihood that the true value lies within the obtained interval.

It is a mystery why lawyers would bother to define something like the confidence interval, and then do it incorrectly.  Here is how Professors Finkelstein and Levin define the confidence interval in their textbook on statistics:

“A confidence interval for a population proportion P is a range of values around the proportion observed in a sample with the property that no value in the interval would be considered unacceptable as a possible value for P in light of the sample data.”

Michael Finkelstein & Bruce Levin, Statistics for Lawyers 166-67 (2d ed. 2001).   This text explains why and where Woodside and Davis went astray:

“It is the confidence limits PL and PU that are random variables based on the sample data. Thus, a confidence interval (PL, PU) is a random interval, which may or may not contain the population parameter P. The term “confidence” derives from the fundamental property that, whatever the true value of P, the 95% confidence interval will contain P within its limits 95% of the time, or with 95% probability. This statement is made only with reference to the general property of confidence intervals and not to a probabilistic evaluation of its truth in any particular instance with realized values of PL and PU.”

Id. at 167-71.

[1] Surely the time has come to stop referring to the Daubert factors and acknowledge that the Daubert case was just one small step in the maturation of evidence law.  The maturation consisted of three additional Supreme Court cases, many lower court cases, and a statutory revision to Federal Rule of Evidence 702, in 2000.  The Daubert factors hardly give due consideration to the depth and breadth of the law in this area.

Second Circuit Hands down a Marvel Opinion on Historian Expert Testimony

August 17th, 2013

“What will history say?  History, sir, will tell lies as usual.”
George Bernard Shaw, The Devil’s Disciple (1901)

 * * * * *

Parties to products liability litigation have for some time resorted to the ruse of using historians as rhetoricians and advocates to argue partisan litigation positions to the jury, in the evidentiary phase of trials.  The obvious opening for this ruse has come in advancing party positions on “state of the art” to claim or defend against negligence.  When plaintiffs use this tactic, they seek not only to introduce evidence of pre-sale belief or knowledge of hazards, but also to disparage any challenges to, or doubts about, hazards as unreasonable, biased, or malicious.  When defendants use this tactic, they of course seek to return the favor, by employing their expert witnesses as advocates on crucial issues of historical knowledge.

Two historian gladiators, David Rosner and Gerald Markowitz, have served as capable arguers in silica, asbestos, lead, and vinyl chloride litigation.  Indeed, you might well expect to meet them at the Argument Clinic, although more recently, they starred in an appearance in a California lead paint case, currently on trial.  See CA Lead Paint Trial: Same old Rosner, Markowitz show (Aug. 07, 2013); Howard Mintz, “Hazardous lead paint: Legal battle comes to trial in California” (July 16, 2013) (quoting Rosner’s email exchange with reporter in which he previews his partisan opinions on lead paint in advance of his testimony).

We can find no clearer statement of judicial antipathy to expert witness advocacy than the famous copyright decision by Judge Learned Hand in Nichols v. Universal Pictures Corp., 45 F.2d 119 (2d Cir. 1930).  Both sides in Nichols presented expert testimony on “dramatic writing” in an effort to prove or disprove a claim that one screenplay infringed upon another. Deprecating the lengthy, argumentative testimony from both sides’ experts, Judge Hand declared that

“[i]t ought not be allowed at all. . . .”

Id. at 123. Judge Hand explained with his usual magisterial authority:

“Argument is argument whether in the box or at the bar, and its proper place is the last.”


Other areas of expertise, besides historical scholarship, fail to satisfy the basic requirements of expert witness testimony. For instance, Judge Hand’s complaints about the “literary critic” expert witnesses in Nichols, have been relodged against “ethics” witnesses. In GST v. Telecommunications, Inc., 192 F.R.D. 109 (S.D.N.Y. 2000), both parties offered expert witness on the ethics of the conduct of corporate officers. Invoking the helpfulness criterion of Federal Rule of Evidence 702, the Court found the proffered testimony would not aid the jury:

“It is evident that the contentious advocacy of the experts – illustrated by conclusions on the credibility of explanations regarding the business judgment of the board of directors . . . in clearly expressed, biased viewpoints – do little to aid the triers of fact on the underlying transactions.”

Id. at 110. The trial court discerned a serious danger that expert testimony on ethics would usurp the jury’s role in applying the law to the facts found in the case. Id. Permitting such testimony would allow expert witnesses to attempt to substitute their judgment for the jury’s. Id.; see, e.g., Pan American World Airways, Inc. v. Aetna Casualty & Surety, 505 F.2d 989, 998 (2d Cir. 1974) (noting disapprovingly that, evidence consisted “largely of hearsay, propaganda, speculation, and conjecture”). See also Imwinkelreid, “Expert Testimony by Ethicists: What Should Be the Norm?” 76 Temple L. Rev. 91, 114, 128 (2003) (noting that normative testimony will virtually always be inadmissible).

Of course, the substitution of an expert witness’s judgment for the jury’s is precisely what many trial lawyers hope to accomplish. Lawyers can select and present expert witnesses based upon their opinions and conclusions, whereas the conclusions of juries are all too unpredictable.  Trial courts must be vigilant to police expert witness opinion testimony in the area of history as much as, if not more than, in the area of scientific testimony. Rule 702’s requirement of knowledge that will assist the trier of fact is designed to prevent expert witnesses from testifying about matters within the common understanding of the jury, and about which the jurors can reason without help from an expert witness. In the Rezulin Multidistrict Litigation (MDL), testimony that was “a narrative of the case which a juror is equally capable of constructing” was precluded.  In re Rezulin Products Liability Litig., 309 F.Supp. 2d 531, 541 (S.D.N.Y. 2004).  Judge Kaplan explained that expert witnesses were not the appropriate conduit for a narrative of events, meetings, regulations, and documents, when they were not percipient witnesses. Such testimony was within the jury’s lay understanding, and the law prohibited the attempt to have expert witnesses “supplant the role of counsel in making argument at trial, and the role of the jury in interpreting the evidence.” Id. at 551.  See generallyNarratives & Historians for Hire”; and “How Testifying Historians Are Like Lawn-Mowing Dogs.”

In Marvel Characters, Inc. v. Kirby, 2013 WL 4016875 (2d Cir. Aug. 8, 2013), the Second Circuit reaffirmed Learned Hand’s jaundiced view of expert witness advocates in the form of historian testimony. Jack Kirby was among the artists responsible for creating comic strip characters of X-Men, the Hulk, Captain America, Thor, and the Fantastic Four. Kirby’s heirs claimed that the intellectual property rights in these characters passed to them.  Marvel Characters, Inc., sought a declaratory judgment that the characters were “works for hire,” now owned by Marvel Entertainment, a subsidiary of corporate oligarch, Walt Disney Co.

The district court rejected the claims of Kirby’s heirs, and the Second Circuit affirmed. Marvel Worldwide, Inc. v. Kirby, 777 F. Supp. 2d 720 (S.D.N.Y. 2011), aff’d, 2013 WL 4016875 (2d Cir. 2013).  In ruling on Marvel’s motion for judgment, the district evaluated and excluded the proffered expert witness testimony of John Morrow and Mark Evanier, who would have testified on the history of the relationship between Marvel and Jack Kirby. 777 F. Supp. 2d 720, 729-30 (S.D.N.Y. 2011). The Second Circuit held that the district court had clearly not abused its discretion in these exclusionary rulings.  Marvel Characters, Inc. v. Kirby, slip op. at 36.

In affirming the rejection of these historians’ proffered opinions, the Circuit waxed  historiosophical:

“We have no doubt that a historian’s ‘specialized knowledge’ could potentially aid a trier of fact in some cases. A historian could, for example, help to identify, gauge the reliability of, and interpret evidence that would otherwise elude, mislead, or remain opaque to a layperson. He or she might helpfully synthesize dense or voluminous historical texts. Or such a witness might offer background knowledge or context that illuminates or places in perspective past events.”

Slip op. at 34 (internal citations omitted).

Morrow and Evanier wandered far outside the permissible boundaries of historian expert testimony.  They sought to marshal opinions based largely upon hearsay statements of various artists, uttered in a variety of settings, about how Marvel treated artists back in the day. From these statements, the aspiring litigation historians speculated about intentions, understandings, and motivations of the historical actors at Marvel, and of Jack Kirby.  Id. at 35.

The appellate court recognized the serious danger of using historian expert witnesses as

“a conduit for introducing hearsay under the guise that the testifying expert used the hearsay as the basis of his testimony.”

Id. (internal citations omitted).  The Circuit recognized that implicit in Rule 703 is something akin to a “best evidence” rule, which relegated the historians to clearly less than best:

“The appropriate way to adduce factual details of specific past events is, where possible, through persons who witnessed those events. And the jobs of judging these witnesses’ credibility and drawing inferences from their testimony belong to the factfinder.”

Id. at 37.  The Circuit also noted that the expert opinion testimony from historians was beset a serious evidentiary challenges. In addition to relevance, legal and logical, and Rule 702, historian opinions raises basic issues about the source of the opinions.

Applying these principles, the appellate court recognized that the heirs’ witnesses were not using specialized knowledge or offering helpful historian insights, but they were marshalling hearsay:

“But Morrow and Evanier do not bring their expertise to bear in any such way. As the district court recognized, their reports are by and large undergirded by hearsay statements, made by freelance artists in both formal and informal settings, concerning Marvel’s general practices towards its artists during the relevant time period.  Drawing from these statements, they then speculate as to the motivations and intentions of certain parties… .”

Id. at 36 (internal citations omitted).

The Second Circuit’s decision is timely.  Perhaps the California trial court pondering the claims against the paint industry will heed the Marvel opinion.  The Marvel Characters opinion should close the door on the use of Rosner and Markowitz’ historical argument, as well as that of other would-be testifying historians in other cases.  In products liability cases, many of the proffered witnesses seek to testify about hearsay statements, and argue inferences about intentions, understandings, and motivations of the historical actors.  Like Morrow and Evanier, they should be excluded from the litigation process.