Holding that, in order to avoid summary judgment, the plaintiffs in a FELA action were required to produce expert testimony that exposure to chemicals played a part in causing their injuries
Holding that epidemiological studies are not required to prove causation, but that a substantial body of epidemiological evidence challenging causation cannot be ignored
Holding experts' use of "weight of the evidence" methodology that regulatory and advisory bodies employed was improper to demonstrate a link between plaintiff's exposure and brain cancer, because "[t]he agencies' threshold of proof is reasonably lower than that appropriate in tort law."
Holding that a right to damages is substantive and governed by state law in a diversity action because the remedy "is inseparably connected with the right of action"
Finding experts' testimony reliable and admissible in part because they "relied not just on studies ... but also on their own wealth of experience and additional literature."
Reversing grant of summary judgment where expert's testimony, which would have created a genuine issue of material fact, was excluded because it was erroneously deemed unreliable and irrelevant