New CSAFE Study Shows Juror Appraisals of Forensic Evidence

A new CSAFE study by Duke Center for Science and Justice Director Brandon Garrett, Research Director William Crozier and Towson University's Jeff Kukucka was released online in late July and will appear in the October issue of Forensic Science International.

The article "Juror appraisals of forensic evidence: Effects of blind proficiency and cross-examination" found that mock jurors were swayed by examiners’ performance on blind proficiency tests; errors on blind proficiency tests made examiners less persuasive to mock jurors; conversely, proficient examiners were favored over examiners of unknown proficiency; and high proficiency somewhat inoculated examiners against cross-examination.

From the abstract:

Forensic testimony plays a crucial role in many criminal cases, with requests to crime laboratories steadily increasing. As part of efforts to improve the reliability of forensic evidence, scientific and policy groups increasingly recommend routine and blind proficiency tests of practitioners. What is not known is how doing so affects how lay jurors assess testimony by forensic practitioners in court. In Study 1, we recruited 1398 lay participants, recruited online using Qualtrics to create a sample representative of the U.S. population with respect to age, gender, income, race/ethnicity, and geographic region. Each read a mock criminal trial transcript in which a forensic examiner presented the central evidence. The low-proficiency forensic examiner elicited a lower conviction rate and less favorable impressions than the control, an examiner for which no proficiency information was disclosed. However, the high-proficiency examiner did not correspondingly elicit a higher conviction rate or more favorable impressions than the control. In Study 2, 1420 participants, similarly recruited using Qualtrics, received the same testimony, but for some conditions the examiner was cross-examined by a defense attorney. We find cross-examination significantly reduced guilty votes and examiner ratings for low-proficiency examiners. These results suggest that disclosing results of blind proficiency testing can inform jury decision-making, and further, that defense lawyering can make proficiency information particularly salient at a criminal trial.