Evidentiary, extraevidentiary, and deliberation process predictors of real jury verdicts

In contrast to the extensive literature based on mock jurors, large-sample studies of decision making by real juries are relatively rare. In this field study, we examined relationships between jury verdicts and variables representing 3 classes of potential determinants-evidentiary, extraevidentiary, and deliberation process-using a sample of 114 criminal jury trials. Posttrial data were collected from 11 presiding judges, 31 attorneys, and 367 jurors using a Web-based questionnaire. The strength of the prosecution's evidence was strongly related to the occurrence of a conviction, whereas most extraevidentiary and deliberation process variables were only weakly to modestly related in bivariate form and when the prosecution's evidence strength was controlled. Notable exceptions to this pattern were jury demographic diversity as represented by the number of different race-gender subgroups (e.g., Black males) present in the jury, and several deliberation process variables reflecting advocacy for acquittal (e.g., presence of an identifiable proacquittal faction within the jury and proacquittal advocacy by the foreperson). Variables reflecting advocacy for conviction were essentially unrelated to jury verdict. Sets of extraevidentiary and deliberation variables were each able to modestly improve the explanation of jury verdicts over prosecution evidence strength in multivariate models. This study highlights the predictive efficacy of prosecution evidence strength with respect to jury verdicts, as well as the potential importance of jury demographic diversity and advocacy for acquittal during deliberation. (PsycINFO Database Record