Designing Optimal Juries

Juries are a fundamental element of the criminal justice system. In this paper, we model jury decision-making as a function of three institutional variables: jury size, voting requirement, and the applicable standard of proof. Changes in jury size, voting requirements, and standards of proof affect the accuracy and cost of criminal adjudication. Our framework helps appraise some U.S. Supreme Court decisions and legal reforms on jury design. We find that the use of smaller or non-unanimous juries, if combined with a high standard of proof, may be superior to alternative jury structures. The results apply not only to juries, but also to other collective decision-making bodies such as court panels, corporate boards, and management teams.