Cognitive Bias and the Evaluation of Forensic Evidence

Academics have warned of the dangers of unconscious biases among forensic examiners for years, but their arguments have gained traction in light of innovative research studies and the momentum for forensic reform brought about by the 2009 NAS report. As defense attorneys prepare to defend a criminal case, they must keep in mind the potential for bias in the interpretation of evidence. A biasing context can take many forms, including extraneous knowledge about a case or suspect, unconscious expectations and desires, knowledge of the conclusions reached by other examiners, and a ranked list of candidate matches from a database. The possibility of cognitive bias in the evaluation of forensic evidence is important information that should be conveyed to jurors so that they may reliably assess the forensic science evidence presented to them.