Confirmation Bias in Forensic Science

The close relationship that forensic practitioners engender with law enforcement agencies renders them susceptible to cognitive bias through the wider problem of information sharing. Confirmation bias occurs when practitioners use selective external information, consciously or unconsciously garnered from their associates, to assist their conclusions. This is a well-studied phenomenon in eyewitness lineups, in which witnessed who are initially tentative with their identifications become positive after learning that the person they identified is the prime suspect according to the police. Confirmation bias has played a role in numerous forensic scandals, and was recently acknowledged as one of the leading cause of the [FBI fingerprint] misidentification of the 2004 Madrid [train] bomber.

C. Michael Bowers, Forensic Testimony, 2013