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In Re Joint Eastern & Southern District Asbestos Litigation: Attaining Sufficiency With Epidemiological Evidence

What is the sufficiency standard of human (epidemiological) evidence of disease causation or health risk necessary to keep "junk science" from being used as evidence once it has been admitted to a jury? According to the U.S. Court of Appeals, Second Circuit 52 F.3d 1124, at 1126 (2nd Cir. 1995):

This case marks the convergence of epidemiological evidence, probabilistic causation in carcinogenic torts, and the important issue of the extent to which a trial court may assess the sufficiency of scientific evidence, in light of the Supreme Court's recent ruling in Daubert . . . The central question before us is the standard governing federal judges' evaluation of the sufficiency—as opposed to admissibility—of scientific evidence already admitted.

Believing the district court overstepped the role contemplated by Daubert and inappropriately usurped the role of the jury, the Appeals Court reinstated a jury verdict for the plaintiff. This is a case of asbestos exposure linked by plaintiff's expert witnesses to colon cancer using numerous human (epidemiological) studies.

Errors were made by the trial court regarding the use of epidemiological evidence:

§ While adopting a minimum relative risk ratio of 1.5 as a threshold for a valid inference of causation, several studies yielding ratios of 1.62, 1.85 and 2.27 were discounted because methodological flaws were noted by other scientists. But any shortcomings should have reduced their weight in evidence instead of being selectively excluded.

§ The trial court believed every admissible study must separately support the causal argument. But in weighing sufficiency, multiple epidemiological studies cannot be evaluated in isolation from each other.

§ The trial court believed its expanded role under Daubert in judging admissibility extended to arguments of sufficiency. But the sufficiency standard was left intact by the Daubert court; summary judgment for the defendant still required "such a complete absence of evidence supporting a verdict that the jury's finding could only have been the result of sheer surmise and conjecture." Samuels v. Air Transport Local 504, 992 F.2d 12 (2d Cir. 1993).

§ Trial courts should not arrogate the jury's role in evaluating the evidence and credibility of expert witnesses by "simply choosing sides in the battle of the experts." Christophersen v. Allied-Signal Corp., 902 F.2d 362 (5th Cir. 1990).

After analyzing the sufficiency of each epidemiological study using the epidemiologist's standard Bradford-Hill criteria [see In re Agent Orange Product Liability Litigation I, 597 F.Supp. 740 (E.D.N.Y. 1984)], the trial court found none of the five criteria were met.

This case serves to illuminate the admonition of Chief Justice Rehnquist who dissented in Daubert: The law does not impose on judges "either the obligation or the authority to become amateur scientists." 113 S.Ct. at 2800.

The application of this case to health risk assessment is far-reaching if one adopts the common conviction that epidemiology is indispensable to reaching a probabilistic inference of disease causation or health risk.

[Contributed by Wayne Roth-Nelson]

CLASSIFICATION: CIVIL LITIGATION; TOXIC CHEMICAL INJURY; SUFFICIENCY OF EVIDENCE FOR CAUSATION

Copyright © 1999 by Tec-Com, Inc.
Last modified July 29, 1999.