Should Jurors Deliberate?

Abstract

Does the accuracy of verdicts improve or worsen if individual jurors on a panel are barred from deliberating prior to casting their votes? I study this question in a model where jurors can choose to exert costly effort to improve the accuracy of their individual decisions. I find that, provided the cost of effort is not too large, it is better to allow jurors to deliberate if jury size exceeds a threshold. For panels smaller than this threshold, it is more effective to instruct jurors to vote on the basis of their private information, without deliberations, and to use a simple majority rule to determine the collective decision (regardless of the voting rule used with deliberations). The smaller the cost of paying attention, the larger the threshold above which the switch to allowing deliberations becomes optimal. However, if the unanimity rule had to be maintained under the no-deliberations system, it would be better to allow deliberation. The results apply to binary decision making in any committee where the committee members incur some effort in reviewing the evidence. Examples are arbitration panels and tenure and promotion committees and some board of director meetings on issues such as whether to dismiss a CEO. As an extension I consider the case where jurors differ in their costs of effort.