How Jurors Evaluate Fingerprint Evidence: The Relative Importance of Match Language, Method Information, and Error Acknowledgment

Authors

  • Brandon Garrett,

  • Gregory Mitchell


  • Simon Cole, Itiel Dror, Jennifer Laurin, John Monahan, Erin Morris, and participants at workshops at the Columbia Law School and University of Illinois College of Law provided helpful comments on a draft.

Address correspondence to Gregory Mitchell, School of Law, University of Virginia, 580 Massie Rd., Charlottesville, VA 22903; email: greg_mitchell@virginia.edu.

Abstract

Fingerprint examiners use a variety of terms and phrases to describe a finding of a match between a defendant's fingerprints and fingerprint impressions collected from a crime scene. Despite the importance and ubiquity of fingerprint evidence in criminal cases, no prior studies examine how jurors evaluate such evidence. We present two studies examining the impact of different match phrases, method descriptions, and statements about possible examiner error on the weight given to fingerprint identification evidence by laypersons. In both studies, the particular phrase chosen to describe the finding of a match—whether simple and imprecise or detailed and claiming near certainty—had little effect on participants' judgments about the guilt of a suspect. In contrast, the examiner admitting the possibility of error reduced the weight given to the fingerprint evidence—regardless of whether the admission was made during direct or cross-examination. In addition, the examiner providing information about the method used to make fingerprint comparisons reduced the impact of admitting the possibility of error. We found few individual differences in reactions to the fingerprint evidence across a wide range of participant variables, and we found widespread agreement regarding the uniqueness of fingerprints and the reliability of fingerprint identifications. Our results suggest that information about the reliability of fingerprint identifications will have a greater impact on lay interpretations of fingerprint evidence than the specific qualitative or quantitative terms chosen to describe a fingerprint match.

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