Management Science and Jury Size

It is impossible in a short article to sort out all the inter-related strands that together constitute the procedures of criminal justice in the United States. Clearly, a most basic principle should be to maximize conviction of the guilty and minimize conviction of the innocent, to the degree that these two goals can be sought simultaneously. This paper isolates the single element of jury size as it relates to the optimizing of these two goals. The number of jurors (usually 6 to 12 in criminal cases) is popularly, and correctly perceived to affect the probability of outcome of any trial: the difficulty lies in determining the several ways that this takes place and relating them correctly. The study described in this paper, based on the quantification of substantial legal data and extensive modeling assumptions, was quoted in some detail in a US Supreme Court case determining the constitutionality of less than six-person juries. The article is preceeded a note from Gene Woolsey, the Editor of the journal.