Use and misuse of epidemiologic data in the courtroom: defining the limits of inferential and particularistic evidence in mass tort litigation.

Medical epidemiology is the cornerstone for understanding the safety and efficacy of drugs and medical devices. Epidemiologic principles provide a statistical basis for determining correlations, and ultimately mathematical causation, between two series of events. Medical epidemiologic evidence and statistical inferences are useful and are now routinely accepted in the courtroom. The complex distribution systems that provide fungible goods throughout the country often preclude the identification of the specific source of an allegedly defective product. An expansion of the principles established in Summers v. Tice and Ybarra v. Spangard provide a logical and rational means for the courts to address products liability issues in cases involving multiple and unnamed defendants. This Article discusses the impact of epidemiology on the judicial process, both in the nature of judicial decision-making and in the nature of the law itself. Part III B discusses the "weak" and "strong" versions of the traditional preponderance of the evidence rule, as recast by recent products liability litigation. The remainder of the Article defines the useful and appropriate scope of epidemiologic evidence, concluding that "intentless" epidemiologic evidence alone cannot support an award of punitive damages.