How Cross-Examination on Subjectivity and Bias Affects Jurors’ Evaluations of Forensic Science Evidence

Abstract

Contextual bias has been widely discussed as a possible problem in forensic science. The trial simulation experiment reported here examined reactions of jurors at a county courthouse to cross-examination and arguments about contextual bias in a hypothetical case. We varied whether the key prosecution witness (a forensic odontologist) was cross-examined about the subjectivity of his interpretations and about his exposure to potentially biasing task-irrelevant information. Jurors found the expert less credible and were less likely to convict when the expert admitted that his interpretation rested on subjective judgment, and when he admitted having been exposed to potentially biasing task-irrelevant contextual information (relative to when these issues were not raised by the lawyers). The findings suggest, however, that forensic scientists can immunize themselves against such challenges, and maximize the weight jurors give their evidence, by adopting context management procedures that blind them to task-irrelevant information.