Opinion ID: 212992
Heading Depth: 2
Heading Rank: 2

Heading: The Concept of Biological Plausibility

Text: The district court also erred in its apprehension of the scientific concept of biological plausibility and its place in Dr. Smith's analysis. The concept of biological plausibility, which numbers among the nine Hill viewpoints, asks whether the hypothesized causal link is credible in light of what is known from science and medicine about the human body and the potentially offending agent. At two places in the court's analysis, it conflated the scientific question of biological plausibility with the legal question of probability. In the court's discussion of the epidemiological evidence, it stated that even if the evidence `suggests' a causal relationship, providing support for Dr. Smith's opinion regarding biological plausibility, a plausible hypothesis is not a reliable inference and is therefore inadmissible. Id. Here, the court not only misconstrued the concept of biological plausibility by equating it with a merely plausible or possible hypothesis, but also misconstrued the concept's role in Dr. Smith's analysis by assuming that Dr. Smith treated the criteria as sufficient grounds for inferring causality (rather than as one consideration that entered into his weighing of the evidence). The court made a similar error in its conclusion, where it stated: While Dr. Smith's hypotheses are, to use his term, plausible, they remain hypotheses, the validity of which has not been reliably established.... [T]he sum of Dr. Smith's testimony, fairly understood, is that benzene might be a cause of APL. Id. Again, the district court misunderstood Dr. Smith to be saying that causation is possible rather than probable. The sum of Dr. Smith's testimony was not merely that it is possible, or even biologically plausible, that benzene causes APL. Rather, the sum of his testimony was that a weighing of the Hill factors, including biological plausibility, supported the inference that the association between benzene exposure and APL is genuine and causal.