The First Circuit Court of Appeals approved the “weight of the evidence” methodology to support the conclusion that benzene can cause leukemia. In Milward v. Acuity Specialty Products Group 639 F.3d 11 (1st Cir. 2011) plaintiffs brought negligence claims against the defendant chemical companies alleging that the rare type of leukemia that the husband suffers was caused by his routine work place exposure to benzene-containing products that had been manufactured or supplied by defendants. Plaintiffs’ expert, a toxicologist, offered testimony supporting the claims that routine exposure to benzene at work triggered the leukemia. The expert used a “weight of the evidence methodology” the “weight of the evidence” approach to making causal determinations involves a mode of logical reasoning often described as “inference to the best explanation” in which the conclusion is not guaranteed by the premises.
In approving the methodology and reversing the district court’s exclusion of the expert’s causation testimony the court said:
“The record clearly demonstrates that Dr. Smith’s opinion was based on an analysis in which he employed the “same level of intellectual rigor” that he employs in his academic work. Kumho Tire, 526 U.S. at 152, 119 S.Ct. 1167. In excluding Dr. Smith’s testimony, the district court did not properly apply Daubert and exceeded the scope of its discretion. We reverse the district court’s judgment for the defendants and its exclusion of Dr. Smith’s testimony, and we remand for proceedings consistent with this opinion”