Three Angry Men: A Game Theoretic Analysis of How The Two-Sided Unanimous Verdict Rule Affects Outcomes in Jury Trials

Abstract

Much has been written about how deliberative bodies such as juries come to decisions with imperfect information, but most of this research assumes either majority rule, one-sided unanimity, or another binary decision rule. We analyze what happens when juries are required to abide by a two-sided unanimous verdict rule in which unanimity is required to convict or acquit a defendant, and if there is no unanimous verdict after a certain number of rounds of voting, there is a mistrial. We nd that two-sided unanimity performs at least as well as simple majority and one-sided unanimity, and it usually performs better.