Jury Size and the Hung-Jury Paradox

Abstract

In the United States, the 1970 Supreme Court decision Williams v. Florida 399 U.S. 78 (1970) reduced from twelve to six the minimum number of jurors required under the Sixth and Fourteenth Amendments. In the hope of improving the legal process with faster deliberation and fewer mistrials, eleven states have used juries of less than twelve in felony cases. This has given origin to an unprecedented natural experiment on jury decision-making. Contrary to the predictions of probability theory, the reduction in jury size has not brought the expected reduction in the number of mistrials. In this paper we provide a possible explanation for this fact. We formulate some propositions considering the case of jury deliberation in the presence of informational cascades. These results have implications not only for juries, but also for democratic theory.