A new report from the National Research Council recommends best practices that law enforcement agencies and courts should follow to improve the likelihood that eyewitness identifications used in criminal cases will be accurate. Science has provided an increasingly clear picture of the inherent limits in human visual perception and memory that can lead to errors, as well as the ways unintentional cues during law enforcement processes can compromise eyewitness identifications.
To increase the likelihood of accuracy in eyewitness identifications, the report recommends that law enforcement agencies use the following practices in handling eyewitness identifications:
- Train all law enforcement officers in eyewitness identification. An eyewitness’s memory of an incident can be contaminated by a wide variety of influences, including interaction with the police. All law enforcement agencies should provide their officers and agents with training about vision and memory, practices for minimizing contamination, and effective eyewitness identification protocols. Police officers should be trained to ask open-ended questions, avoid suggestiveness, and efficiently manage scenes with multiple witnesses (for example, minimizing interactions among witnesses).
- Implement double-blind lineup and photo array procedures. Even if a line-up administrator doesn’t verbally tell the witness which person in a lineup or photo array is the suspect, he or she could still convey the suspect’s identity through unintended body gestures, facial expressions, or other nonverbal cues. Using a double-blind procedure, in which neither the witness nor the administrator knows which person in the lineup or photo array is the suspect, can avoid this inadvertent bias.
- Develop and use standardized witness instructions. The report recommends the development of a standard set of easily understood instructions to use when engaging a witness in an identification procedure. Witnesses should be instructed that the perpetrator may or may not be in the photo array or lineup and that, regardless of whether the witness identifies a suspect, the investigation will continue. Such instructions should be used consistently in all photo arrays and lineups and could either be pre-recorded or read aloud by administrators.
- Document witness confidence judgments. Evidence indicates that an eyewitness’s level of confidence in their identifications at the time of trial is not a reliable predictor of their accuracy. The relationship between confidence and accuracy is likely to be strongest at the time of initial identification. Law enforcement should document the witness’s level of confidence verbatim at the time when she or he first identifies a suspect.
- Videotape the witness identification process. To obtain and preserve a permanent record of the conditions associated with the initial identification, the committee recommended that video recording of eyewitness identification procedures become standard practice.
The report also gives some best practices for the Courts, but I won’t get into those for this blog post. These best practices are recommended, said the Report, because:
… [M]emory is often an unfaithful record of what was perceived through sight; people’s memories are continuously evolving. As memories are processed, encoded, stored, and retrieved, many factors can compromise their fidelity to actual events. Although the individual may be unaware of it, memories are forgotten, reconstructed, updated, and distorted.