Jury Size and the Free Rider Problem

Abstract
In recent times, judges in the United States have said that 6‐person juries are inferior to 12‐person juries. But by what reasoning is a smaller jury inferior? One argument is the Condorcet jury theorem, which says that a larger jury will reach a more accurate decision. This, however, assumes that the information of each juror is independent of the size of the jury. I show that a juror's information does depend on the size of the jury. In a larger jury panel each juror has less incentive to pay attention in the court, even though they are all pledged to hear and deliver a verdict on a trial. Because of the free‐rider problem, a larger jury may actually make poorer decisions. The results apply to many environments in which decisions are made by committees and work teams.