Deceptively Simple: Framing, Intuition and Judicial Gatekeeping of Forensic Feature-Comparison Methods Evidence

Abstract

For many decades, prosecutors have relied on feature-comparison methods (FCM) of forensic science evidence, including hair, fingerprints, toolmarks, handwriting, and bitemarks. Since the late 1980s, scholars and practitioners have raised serious questions about the reliability and error rates of such evidence. Two national bodies have published serious criticism of FCM evidence: the 2009 Committee of the National Research Council of the National Academy of Sciences; and the 2016 President’s Council of Advisors on Science and Technology. Despite these concerns and proof from the Innocence Project data that poor quality forensic science evidence has been a substantial component in wrongful convictions, courts continue to admit FCM evidence routinely and with little analysis, generally avoiding application of the Daubert factors related to reliability. This article questions why courts are unreceptive to challenges about the reliability of such evidence and suggests that judges perceive feature-comparison evidence as fairly straightforward and intuitively accurate. As such, courts often unknowingly rely upon heuristic approaches to the evidence — that is, cognitive shortcuts to manage complexity. By using these shortcuts, rather than rigorously evaluating reliability, decisions may inadvertently incorporate cognitive biases, including belief perseverance, confirmation bias, and assumptions of simplicity. If judges can appreciate that feature-comparison “matching” is a complex, multifaceted procedure, they might become more willing to engage in a deeper, science-based review of the evidence and better understand its shortcomings and limitations.