Lineups

Abstract

Lineups are conducted in the course of police investigations when a crime has been witnessed by one or more people. A lineup typically consists of a person whom the police believe committed the crime (i.e., the suspect) and some number of people who are known to be innocent of the crime (i.e., fillers). When the police have developed a suspect, they show witnesses a lineup to test whether they will claim that the suspect is the person who committed the crime (i.e., the perpetrator). If so, the witness is said to have made a positive identification of the suspect. What is not clear, at least in real-world investigations, is whether that identification is correct, because sometimes suspects are guilty and sometimes they are innocent. Since the late 1970s, psychologists have conducted experiments to find lineup procedures that decrease the likelihood that witnesses will mistakenly identify innocent suspects. These experiments are typically conducted in laboratory settings in which researchers expose participants to a simulated crime, often on videotape. After the participant-witnesses have viewed the crime, they are asked to attempt an identification from a lineup. In the laboratory, researchers can vary whether the perpetrator appears in that lineup. When the perpetrator is present in the lineup (i.e., a target-present lineup), the witness can identify the suspect (a correct identification), identify a filler, or say that the perpetrator is not there (an incorrect rejection of the lineup). When the perpetrator is not present (i.e., a target-absent lineup), the witness can make a mistaken identification of the suspect, identify a filler, or correctly reject the lineup. Using this method, researchers have identified lineup procedures that decrease mistaken identifications, which are the leading cause of wrongful convictions among those who have been exonerated by DNA tests conducted after trial. This article contains sections describing comprehensive General Overviews of research on lineups, research demonstrating that Live Lineups Are Equivalent to Photo Lineups, and Policy Recommendations and Best Practice Guidelines. The remaining sections describe many of these policy recommendations, including how Lineups Are Superior to Showups, having an Evidence-Based Suspicion for placing a suspect in a lineup, unbiased Lineup Composition, Double-Blind Administration, proper Lineup Instructions, collecting witnesses’ Confidence Statements in the accuracy of their identification immediately after the initial identification, Video Recording Identification Procedures, and avoiding Repeated Lineups. An additional section addresses special issues that need to be considered when Conducting Lineups with Children.