Battling to a draw: Defense expert rebuttal can neutralize prosecution fingerprint evidence

Abstract

The present study examined whether a defense rebuttal expert can effectively educate jurors on the risk that the prosecution's fingerprint expert made an error. Using a sample of 1716 jury-eligible adults, we examined the impact of three types of rebuttal testimony in a mock trial: (a) a methodological rebuttal explaining the general risk of error in the fingerprint-comparison process; (b) a new-evidence rebuttal concluding the latent fingerprint recovered in this case was not suitable for use in a comparison; and (c) a new-evidence rebuttal excluding the defendant as the source of the latent fingerprint. All three rebuttals significantly altered perceptions of the prosecution's fingerprint evidence, but new-evidence rebuttals proved most effective. The effectiveness of the rebuttals depended, however, on whether jurors were more concerned about false acquittals or false convictions.

Human Factors in Forensic Science: Psychological Causes of Bias and Error

“…Relatedly, recent data from Martire et al (2020) suggest that jurors may be unable-not unwilling-to critically evaluate forensic evidence, such that testimony from an opposing expert and/or judicial instructions may help sensitize them to invalid forensic testimony. Two studies (i.e., Eastwood & Caldwell, 2015;Mitchell & Garrett, 2021) have now found that opposing expert testimony was somewhat effective in this regard, though this question warrants further investigation.…”

Juror perceptions of opposing expert forensic psychologists: Preexisting attitudes, confirmation bias, and belief perseverance.

“…However, these findings suggest it could be beneficial to randomize the order of presentation or adjust the order in which the defense and prosecution present when there is a high risk for jurors to be biased away from the presumption of innocence. The most realistic solution would be to make jurors aware of the impact these factors using research-based juror instructions (Garrett et al, 2020), or ensuring that these issues are addressed in the expert's testimony (Mitchell & Garrett, 2021) or cross-examination (Crozier et al, 2020).…”