Thursday, November 26, 2015

Cell Phones, Brain Cancer, and Scientific Outliers Are Not the Best Reasons to Abandon Frye v. United States

Two days ago, the District of Columbia Court of Appeals (the District’s highest court) heard oral argument 1/ on whether to discard the very test that its predecessor introduced into the law of evidence in the celebrated — and castigated — case of Frye v. United States. 2/ That was 1923, and the evidence in question was a psychologist’s opinion that a systolic blood pressure test showed that James Alphonso Frye was telling the truth when he recanted his confession to a notorious murder in the District. With nary a citation to any previous case, the Court of Appeals famously wrote that
[W]hile courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs. 3/
Now it is 2015, the case is Murray v. Motorola, Inc., 4/ and the proffered evidence is expert testimony that cell phones cause (or raise the risk of) brain cancer. The methods used to form or support this opinion or related ones range from what the court calls “WOE” (the expert says, I thoroughly assessed the “weight of evidence”), to “PDM” (I considered the evidence of causation pragmatically, with the “Pragmatic Dialog Method”), to “a literature review” (I read everything I could find on the subject), to “laboratory experiments” (I conducted in vitro exposure of cells, with results that may not have been replicated), and to “experience as a toxicologist and pharmacologist” to show that “it is generally accepted to extrapolate findings from in vitro studies in human and mammalian cells to predict health effects in humans.”

The trial judge, Frederick H. Weisberg, ruled much of this testimony admissible on the theory that regardless of the extent to which the conclusions are within the mainstream of scientific thinking, the “methods” behind them were generally accepted in ascertaining carcinogenicity. He chastised the defense for “repeatedly challeng[ing] plaintiffs' experts on the ground that their conclusions and opinions are not generally accepted.” As he construed Frye, “[e]ven if 99 out of 100 scientists come out on one side of the causation inference, and only one comes out on the other, as long as the one used a ‘generally accepted methodology,’ Frye allows the lone expert to testify for one party and one of the other ninety-nine to testify for the opposing party.” Having placed himself in this box, Judge Weisberg asked the Court of Appeals to let him out, writing that “most, if not all, of Plaintiffs' experts would probably be excluded under the Rule 702/Daubert standard based on the present record” and granting the defendants' request to allow them to appeal his ruling immediately.

Defendants then convinced the Court of Appeals to jump in. Normally, the appellate court would review only the final judgment entered after a trial. In Murray, it granted an interlocutory appeal on the evidentiary ruling. Not only that, but it agreed to sit en banc, with all nine judges participating rather than to act through a normal panel of three randomly selected judges.

The question before the en banc court is thus framed as whether to replace the jurisdiction’s venerable Frye standard with the approach sketched in Daubert v. Merrell Dow Pharmaceuticals. 5Daubert changes the focus of the judicial inquiry from whether a theory or technique is generally accepted to whether it is scientifically valid. (see Box: What Daubert Did).

But does Frye really require Judge Weisberg to accept evidence that Daubert excludes in this case? The case, I shall argue, is not about Daubert versus Frye. It is about methodology versus conclusion. The judge's construction of Frye as sharply confined to “methodology” is what makes it impossible for him to reject as inadmissible the theory that cell phones cause brain cancers even if it is plainly not accepted among knowledgeable scientists. And that is just as much a problem under Daubert as it is under Frye. Daubert specifically states that the subject of the inquiry “is the scientific validity ... of the principles that underlie a proposed submission. The focus, of course, must be solely on principles and methodology, not on the conclusions that they generate.” 6/ Judge Weisberg decided that principles or putative methodologies like WOE, PDM, literature review, extrapolation from in vitro experiments, and experience are all generally accepted among scientists as a basis for inferring carcinogencity. But if this is correct, and if it insulates claims of general causation from scrutiny for general acceptance under Frye, then it does the same under Daubert (as originally formulated). 7/ Surely, weighing all the relevant data, being pragmatic, studying the literature, considering experiments, and using experience is what scientists everywhere do. They do it not out of habit, but because these things tend to lead to more correct conclusions (and less criticism from colleagues) than the alternatives of not weighing all the data, being doctrinaire, ignoring the literature, and so on.

In Daubert, the U.S. Supreme Court did not rule that Frye was antiquated or not up to job of screening out dangerous and dubious scientific evidence.  Rather, the Court reasoned that Congress, in adopting the Federal Rules of Evidence in 1975, had implicitly dropped a strict requirement of general acceptance. The Court then read Federal Rule 702 as requiring scientific evidence to be, well, “scientific,” as determined by district courts that could look to various hallmarks of scientifically warranted theories. One important criterion, the Court observed, was general acceptance. But such acceptance was no longer dispositive. It was only an indicator of the scientific validity that courts had to find in order to admit suitably challenged scientific evidence.

A majority of U.S. jurisdictions (41 according to the trial court order in Murray), either by legislation or judicial decision, follow the Daubert approach for filtering out unvalidated or invalid scientific evidence (although they still place great weight on the presence of absence of general acceptance in the relevant scientific community). At least one state, Massachusetts, still clings to Frye while embracing Daubert.

The problem with the toxic tort cases like Murray is that the line between “method” and “conclusion” is difficult to draw, and Judge Weisberg draws it in the wrong place. Although his opinion cites to (the first edition of) Wigmore on Evidence: Expert Evidence, it ignores the warning (in § 6.3.3(a)(1) of the second edition and § 5.2.3 of the first edition) that
Occasionally, however, courts define the theory or method at so high a level of abstraction that all kinds of generally applicable findings can be admitted without attending to whether the scientific community accepts them as well founded. For example, in Ibn-Tamas v. United States, [407 A.2d 626 (D.C. 1979),] the District of Columbia Court of Appeals reasoned that a psychologist's theory of the existence and development of various characteristics of battered women need not be generally accepted because an overarching, generally accepted methodology — clinical experience — was used to study the phenomenon. The problem, of course, is that such reasoning could be used to obviate heightened scrutiny for virtually any scientific development [citing, among other cases, Commonwealth v. Cifizzari, 492 N.E.2d 357, 364 (Mass. 1986) (“to admit bite mark evidence, including an expert opinion that no two people have the same bite mark, a foundation need not be laid that such identification technique has gained acceptance in the scientific community. What must be established is the reliability of the procedures involved, such as X-rays, models, and photographs.”)]. Indeed, in developing the lie-detection procedure used in Frye, Marston applied generally accepted techniques of experimental psychology to test his theory and equipment. Thus, an exclusively “high-level” interpretation of Frye is untenable. 8/
The opinion in Murray also overlooks the more extended analysis in Wigmore of why causation opinions in toxic tort cases should be considered theory rather than conclusions within the meaning of Frye. 9/ It would make no sense to ask whether psychologists generally accept the proposition that Marston correctly measured the defendant's blood pressure or correctly applied some formula or threshold that indicated deception. Such case-specific facts do not appear before any general scientific community for scrutiny. On the other hand, whether elevated blood pressure is associated with deception, how it can be measured, and whether a formula or threshold for concluding that the defendant is deceptive or truthful are trans-case propositions that should be part of normal scientific discourse.

The same is true of claims of carcinogenicity. Whether cell phones can cause brain cancer at various levels of exposure are trans-case propositions that stimulate scientific dialog. The Frye test can function just as well (or as poorly) in vetting expert opinions that exposure can cause cancer as in screening a psychologist's opinion that deception can cause a detectable spike in blood pressure. In sum, denominating trans-case conclusions that have been or could be the subject of scientific investigation and controversy as "conclusions" that are beyond the reach of either Frye or Daubert is a category mistake.

There is another way to make this point. Given all the usual reasons to subject scientific evidence to stricter-than-normal scrutiny, courts in Frye jurisdictions need to consider whether it is generally accepted that the body of scientifically validated findings on which the expert relies is sufficient to justify, as scientifically reasonable, the trans-case conclusion. Thus. the Ninth Circuit Court of Appeals in Daubert originally reasoned — on the basis of Frye — that in the absence of some published, peer-reviewed epidemiological study showing a statistically significant association, the causal theories (whether they are labelled general premises or specific conclusions) of plaintiffs’ expert were inadmissible. The court determined that the body of research, namely, “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.” 10/ It was appropriate — indeed, necessary — to consider all the “available ... studies,” but under Frye, there still had to be general acceptance of the proposition that drawing an inference of causation from such studies was generally accepted as scientifically valid. Gussying up the inferential process as a WOE analysis (or anything else) cannot alter this requirement.

Whether or not the Court of Appeals switches to Daubert, it should correct the trial court's blanket refusal to consider whether the theory that cellphones ever cause brain cancer at relevant exposure levels is generally accepted. General acceptance may not be determinative under Daubert, but it remains important. Whether the inquiry into this factor is compelled and conclusive under Frye or inevitable and influential under Daubert, it should not be skewed by a misconception of the scope of that inquiry. In the end, the courts in Murray should realize that
the choice between the general-acceptance and the relevancy-plus standards may be less important than the copious quantities of ink that courts and commentators have spilled over the issue would indicate. [O]ne approach is not inherently more lenient than the other—the outcomes depend more on how rigorously the standards are applied than on how the form of strict scrutiny is phrased. 11/
  1. Ann E. Marimow, D.C. Court Considers How To Screen Out ‘Bad Science’ in Local Trials, Wash. Post, Nov. 24, 2015
  2. 293 F. 1013 (D.C. Cir. 1923).
  3. Id. at 1014.
  4. No. 2001 CA 008479 B (D.C. Super. Ct.), available at
  5. 509 U.S. 579 (1993).
  6. Id. at 594–95 (emphasis added).
  7. In General Electric Co. v. Joiner, 522 U.S. 136 (1997), the Supreme Court blurred the distinction between methodology and conclusion, and Congress later amended Rule 702 to incorporate this shift. The result is that in federal courts, it is less important to draw a better line than the one in Murray and Ibn-ThomasSee David H. Kaye, David A. Bernstein, and Jennifer L. Mnookin, The New Wigmore: A Treatise on Evidence: Expert Evidence § 9.2.2 (2d ed. 2011).
  8. Id. § 6.3.3(a)(1).
  9. Id. § 9.2.3(b).
  10. Daubert v. Merrell Dow Pharms., Inc., 951 F. 2d 1128, 1131 (9th Cir. 1991).
  11. Kaye et al., supra note 7, § 7.2.4(a).
Postscript: A more extensive version of these comments appears in the Bloomberg BNA Product Safety & Liability Reporter (14 Dec. 2015) and in the Expert Evidence Reporter (21 Dec. 2015).

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