The police lineup is a common tool for eyewitness identifications of suspects in criminal cases. Forensic DNA testing of people convicted by eyewitness identification evidence and field studies of police lineups, however, have revealed that mistaken identification from lineups is not uncommon. Controlled laboratory experiments have isolated numerous variables that contribute to mistaken identifications from lineups, some of which are controllable by the criminal justice system (e.g., various biases in the lineup or its procedure) and some of which are not controllable by the criminal justice system (e.g., witnessing conditions, stress).