In every toxic tort, medical device, and pharmaceutical product liability case, a threshold issue is whether the product, device, or substance is even capable of causing the alleged harm in some part of the population. To establish this, lawyers rely first and foremost on epidemiological experts and research, the “gold standard” of general causation evidence. Causation, however, is a continuum, and no single study can prove causation.

If the plaintiff’s epidemiological testimony and related studies are excluded under Federal Rule of Evidence 702 and Daubert, the litigation will most likely end, or at least be significantly narrowed. Thus, admissibility under FRE 702 and Daubert is fiercely litigated in most cases.

Courts are increasingly taking a “hard look” at experts’ methodologies and assessing whether the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case. For example, courts are analyzing experts’ logic, asking if their final opinions exceed the limits of applicable studies, and being sensitive to when experts are “cherry-picking” the evidence to fit the desired conclusions.