Many factors contribute to whether juries reach right verdicts. Here we focus on the role of diversity. Direct empirical studies of the effect of altering factors in jury deliberation are severely limited for conceptual, practical, and ethical reasons. Using an agent-based model to avoid these difficulties, we argue that diversity can play at least four importantly different roles in affecting jury verdicts. We show that where different subgroups have access to different information, equal representation can strengthen epistemic jury success, and if one subgroup has access to particularly strong evidence, epistemic success may demand participation by that group. Diversity can also reduce the redundancy of the information on which a jury focuses, which can have a positive impact. Finally, and most surprisingly, we show that limiting communication between diverse groups in juries can favor epistemic success as well.