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Exposure to irrelevant contextual information prompts confirmation-biased judgments of forensic science evidence (Kassin, Dror, & Kukucka, 2013). Nevertheless, some forensic examiners appear to believe that blind testing is unnecessary. To assess forensic examiners’ beliefs about the scope and nature of cognitive bias, we surveyed 403 experienced examiners from 21 countries. Overall, examiners regarded their judgments as nearly infallible and showed only a limited understanding and appreciation of cognitive bias. Most examiners believed they are immune to bias or can reduce bias through mere willpower, and fewer than half supported blind testing. Furthermore, many examiners showed a bias blind spot(Pronin, Lin, & Ross, 2002), acknowledging bias in other domains but not their own, and in other examiners but not themselves. These findings underscore the necessity of procedural reforms that blind forensic examiners to potentially biasing information, as is commonplace in other branches of science.

Psychology has made a tremendous contribution to law by showing the malleability of eyewitness perception and memory, and developing best practices for obtaining eyewitness identifications. We suggest that even expert scientific witnesses, which the court heavily relies on as objective and impartial, are also susceptible to bias from various psychological influences. For example, forensic examiners’ interactions with detectives and exposure to information about the case can bias their judgments. We discuss the ten commentaries on these issues across a range of forensic science domains, and affirm what reforms are needed.

► The forensic sciences are subject to contextual bias and fraught with error. ► Basic psychology shows that context can taint perception, judgment, and behavior. ► Newer studies find that biasing information likewise impacts forensic scientists. ► Recommendations are given to reduce the effect of bias in forensic labs and courts.