Communicating Forensic Science Evidence : The Effect of Best Practice Recommendations on the Pre-Trial Evaluations of Lawyers and Laypeople.

Forensic science laboratories have been criticised over their unscientific, inconsistent, and inadequate communication standards, which may cause non-scientist decision-makers (e.g. lawyers and defendants) to give undue weight to forensic science evidence. While there are safeguards in place during the trial process that might alert a decision-maker to the limitations of forensic science evidence, a majority of criminal cases are resolved before trial, and these safeguards do not exist in this pre-trial process. This means that there are many opportunities for problems and misunderstandings to have significant impacts in the pre-trial process unless we improve upon communication standards for forensic practitioners written reports. This PhD thesis examines whether forensic reports that are more compliant with best practice recommendations facilitate evaluations and decisions that lawyers and people receiving legal advice may need to make when preparing for trial, and includes five experiments with a total of 2488 participants (including 349 legal trainees and practitioners). We found mixed effects of report compliance on pre-trial decisions. For laypeople recruited from the general public, we found that providing more of the recommended information in forensic reports did not significantly affect lay-peoples’ decisions or underlying perceptions of the persuasiveness of the evidence when the forensic discipline was highly reliable. However, when the discipline had less evidence for its reliability, community participants provided significantly lower ratings of persuasiveness when provided with more recommended information in their forensic report. In contrast, we found that legal trainees and practitioners were overall more sceptical of forensic science evidence than laypeople recruited from the general public. Additionally, we found that providing more of the recommended information in expert reports did not significantly affect legal trainees and practitioners’ decisions or underlying perceptions about the persuasiveness of forensic science evidence. Extending these findings, we also evaluated which specific sections of recommended information affected lay participants’ pre-trial decisions and evaluations, and in what ways. Persuasiveness ratings were significantly increased by providing information about assumptions and underlying facts and decreased by providing information about discipline foundational validity and human factors and performance. These results provide significant insights into the impact of using best practice recommendations as to the content in forensic reports to improve pre-trial decision-making