Eyewitness identification testimony can be very persuasive. According to former U.S. Supreme Court Justice William Brennan, “[T]here is almost nothing more convincing than a live human being who takes the stand, points a finger at the defendant, and says ‘That’s the one!’” Such testimony, however, is not always reliable.
Eyewitness misidentification contributed to approximately 71% of the more than 300 wrongful convictions in the United States overturned by post-conviction DNA evidence.
Contrary to what most people think, memory does not operate like a videotape. Scientific research has shown that memory is a constructive, dynamic, and selective process that can be influenced by many factors. Researchers recommend that eyewitness identifications be treated as trace evidence that can be distorted, contaminated or degrade over time. Investigators must use care in obtaining identification evidence to maintain its integrity and reliability, and to minimize the chances of misidentification.
Eyewitness identification experts have made several recommendations regarding the proper administration of identification procedures, including the following:
Complete description: Before conducting an identification procedure, police should obtain and document as complete a description of the suspect as possible.
Blind administration: To the extent possible, identification procedures should be conducted by “blind” administrators – officers who do not know which of the individuals in a lineup or photo array is the suspect. If a blind administrator is unavailable, the Folder System may be used to “blind” the officer administering the procedure.
Standard instructions: Police should provide witnesses with a standard set of instructions, including: That it is just as important to clear a person from suspicion as to identify a person as the wrongdoer; that the person who committed the crime may or may not be in the lineup or photo array; in the case of a photo array (or a lineup done some time after the crime), that individuals may not appear exactly as they did on the date of the incident; that regardless of whether an identification is made or not made, the investigation will continue.
Sequential presentation: Individuals in lineups and photo arrays should be presented to witnesses sequentially, rather than simultaneously.
Level of certainty: At the conclusion of an identification procedure where the witness has made a positive identification, the officer should ask the witness to describe his or her level of certainty about the identification.