Trials are supposed to be not only fair and accurate but also efficient. Evidence law is meant to facilitate trials, and, at the same time, to encourage and protect important societal values and relationships. In pursuit of these goals, those who create the rules (i.e., common-law judges and modern drafting committees) must engage in amateur applied psychology. Their task requires them to employ what they think they know about the ability and motivations of witnesses to perceive, store, and retrieve information; about the effects of the litigation process on testimony and other evidence; and about people's capacity to comprehend and evaluate evidence. These are the same phenomena studied by cognitive psychology and social psychology. Further, psychology examines the role of emotion, credibility, expert influence, and other relevant topics. The rules of evidence restrain lawyers from using the most robust weapons of influence, and direct judges to exclude certain categories of information, limit it, or instruct juries on how to think about it. The Psychological Foundations of Evidence Law draws on the best current psychological research to identify and evaluate the choices implicit in the rules of evidence, and suggest alternatives that psychology reveals as more likely to accomplish the law’s goals. This interdisciplinary book is aimed at lawyers, judges, researchers, and students, and seeks to provide all with a better understanding of the psychology of what is perhaps the most psychologically connected of legal subjects.