Evidence and Expectations: A Look into How DNA Impacts Jury Decisions in Criminal Trials

Abstract

Using DNA evidence in the courtroom is a practice that has increased over the last twenty years (Lieberman et al., 2008). Past research has shown that the mere presence of this scientific evidence in prosecutorial arguments increases the likelihood of a guilty verdict, even if the information has been severely mishandled (Lieberman et al., 2008). This study uses previously collected mock jury data to determine the effects, if any, mitochondrial DNA or mtDNA testimony has on a juror's perceived importance and understanding of the trial proceedings. The original trial this study was based on resulted in a guilty decision. Therefore, for the purposes of this study, "guilty" is considered a reliable outcome. The following also addresses the extent of group influences on the decision making process using juror thoughts regarding the verdict before and after deliberations. The study finds a positive effect between importance/understanding and the propensity to find the defendant guilty. Also, little group effects were found before and after deliberation, revealing consistency in juror thought.