Effects of pretrial juror bias, strength of evidence and deliberation process on juror decisions: new validity evidence of the Juror Bias Scale scores

Abstract

This study examines the validity of the Juror Bias Scale scores in relation to the mock juror decisions reached in two real life homicide cases before and after the deliberation process. The judicial cases used varied in terms of the ambiguity of the evidence presented at both trials. The WLS methodology for statistical modelling of categorical data was used to analyse data. The findings indicated that the Juror Bias Scale scores successfully predict the verdicts and other related questions before and after deliberations in the case with ambiguous evidence. Furthermore, deliberations caused a generalisation effect on the pretrial juror bias in such a case, and enhanced the differences between defense-biased and prosecution-biased jurors in the verdicts delivered after deliberations. The implications of these findings are discussed in relation to the use of pretrial juror bias questionnaires in jury selection.