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Third Circuit Upholds Exclusion of Plaintiff's Causation Expert
June 8, 2011 by Sean Wajert
The Third Circuit last week affirmed the exclusion of expert testimony in a toxic tort suit in
which plaintiff alleged defendants' insecticide products gave him non-Hodgkin's lymphoma.
Pritchard v. Dow AgroSciences, et al., No.10-2168 (3d Cir. 2011).
Plaintiff claimed that he contracted cancer from a pesticide produced by defendant Dow
AgroSciences. His wife claimed to have suffered derivative injuries. In support of their
complaint, the Pritchards solicited the expert testimony of Dr. Bennet I. Omalu, who provided
the District Court with a report and, later, a declaration, stating that Dursban caused the
cancer. Although the trial court found Dr. Omalu to be a qualified expert, it ruled (on Dow's
motion) that his proposed testimony was unreliable and therefore inadmissible at trial under
Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993). The exclusion of Dr. Omalu's
testimony doomed the lawsuit, because plaintiffs had no other evidence of causation. Plaintiffs
appealed.
The appeal tried to raise the issues surrounding the intersection of federal law, rules of
evidence underlying Daubert, and state law, which supplies the elements of a claim (including
causation) in a diversity case. Plaintiffs argued that in the course of finding that Dr. Omalu's
testimony was unreliable, the District Court erroneously relied on principles that were
supposedly at odds with state (Pennsylvania) substantive law governing the level of certainty
required to establish causation, having to do with idiopathic disease and epidemiological
studies.
It is true that the trial court noted that Dr. Omalu did not rule out unknown or idiopathic causes;
that the court considered the fact that the epidemiological study on which the doctor wished to
rely showed only a relative risk of 2.0; and that the court observed that the proposed testimony
was not grounded in science as Dr. Omalu has not presented any statistically significant
evidence showing an association between the chemical agent at issue and non-Hodgkins
lymphoma. See Pritchard v. Dow Agro Sciences, 705 F. Supp. 2d 471, 492, 486, 493 (W.D.
Pa. 2010).
However, the trial court considered these factors among “a host of other deficiencies,” as
components of a determination that the proffered testimony failed to satisfy the admissibility
standard. The trial court did not adopt any bright-line rules, but instead evaluated the plaintiffs'
proffer using a flexible approach as directed by the Court of Appeals in Heller v. Shaw
Industries, 167 F.3d 146 (3d Cir. 1999). This was an evidentiary ruling, separate and distinct
from any substantive question regarding causation (which the court never had reason to
reach).
Plaintiffs also argued that the court had engaged in some kind of improper balancing of
plaintiffs' scientific evidence vs. defendants'. But the district court engaged in no such
balancing. Instead, it rightly concluded that Dr. Omalu's proposed testimony was unreliable
