Untangling causation issues in law and medicine: hazardous substance litigation.

Judges and juries are increasingly being asked to settle questions about disease caused by hazardous products. With the growth of litigation on toxic substances and unsafe products, more and more courts must wrestle with the complicated scientific proof of the relation between exposure and disease or injury. This proof frequently involves the use of probabilistic evidence in the form of statistical tests and epidemiologic studies. Anglo-American law relies on deductive notions of causation and is suspicious of probabilistic evidence of causation. As a result, court decisions of hazardous substance cases are sometimes based on a confused understanding of the critical causal connection. Physicians who testify in such cases, either as the treating doctor or as expert witnesses, must be aware of the court's difficulty with probabilistic evidence. In addition, physicians must state clearly the role of such evidence in the identification of a hazardous substance as the cause of a disease or injury.