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

Abstract

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.

Social cognitive processes explain bias in juror decisions

“…Various extra-evidentiary factors can bias the outcome of juror decisions.The most prominently studied of these biasing factors include racial or cultural prejudices and stereotypes. For example, a number of studies have focused on the effects of race and gender on convictions in the criminal justice system (Anwar et al, 2012;Devine et al, 2016;Flanagan, 2018). Experimental evidence compliments this research.…”

INVITED ESSAY: Jury Decision Making: Is the Devil in the Details? Observations of a Criminal Justice Professor from Inside the Jury Room

“…The deliberation process includes the style of the discussion that takes place, the individuals or subgroups that offer dissenting views, the number of votes taken, etc. Devine et al (2016) found that the strength of the evidence had the greatest influence on participants, but that extra-evidentiary and deliberation factors might also influence verdicts. Earlier work by Devine et al (2007, p. 300) found that juries did well in some aspects of deliberation but not others.…”

“…Further, they state that the research on mock juries has often been conducted with college students (who represent a convenience sample for academics studying jury decision making). Devine, Krouse, Cavanaugh, and Basora (2016) summarized the issue of reliance on college student samples: "Overreliance on studies of undergraduate students making noninteractive decisions about a fictional trial runs the risk of providing a misleading picture of how real juries make decisions. There is a need for more field research that complements and extends the laboratory research with mock jurors" (Devine et al,p.…”

Evidentiary instructions improve mock juror assessment of feature-comparison evidence

“…Participants also completed the survey in isolation, and the group dynamics of jury deliberation were thus not accounted for. This could be a disadvantage, although Devine et al (2016) found that jury deliberation seems to have little impact on the final verdict. It was decided to adopt a Likert scale approach to assessing innocence in order to be able to examine more sophisticated verdict changes.…”