The police lineup involves the presentation of multiple individuals (a suspect and a group of known innocent individuals known as fillers) to a witness in order to determine whether or not the witness recognizes the suspect as the perpetrator of the crime. The purpose of presenting a suspect within a group of other individuals is to increase the likelihood that a witness who identifies the suspect is doing so because the suspect is the perpetrator and not simply because the witness feels compelled to identify someone. A properly constructed and administered lineup provides information regarding the likelihood that the suspect is the perpetrator. In U.S. agencies, lineups are typically administered with photo spreads: A photograph of the suspect is presented among photographs of persons of similar appearance. Historically, physical lineups containing a set of people, not photographs, have been used, but their use today is extremely rare. Lineups as a means of criminal identification have been used since the 1800s, but the refinement and sophistication embedded in the policies and procedures that have come about in the 2000s are based largely on empirical science conducted since 1970. This article discusses considerations and factors involved in administering lineups and presents evidence-based recommendations for conducting police lineups.
Memory Considerations for Police Lineups
All identification procedures are founded on the premise that the witness actually saw and remembers the offender. While obvious, this assumption is complex. Seeing is one thing, forming a memory rich and detailed enough for a reliable identification weeks later is another. An optimal environment for forming a memory would require observing an undisguised face moving slowly in angle and posture at a near distance (5′–10′) for a short time (∼10″) under good daylight illumination in the absence of threats to the observers’ life and safety, without competing demands on one’s attention to the face observed and without intervening objects (e.g., bushes, screens, glass or plastic media providing reflections). The memory formed is nearly always better if the face is of the same appearance group as the observer: A contrast (e.g., African American or European American faces for Mexican American observers, and vice versa) leads to less effective information gathering from the face.
A large scientific literature exists on the factors affecting perception and memory for faces. However, sorting out their influence in a particular instance is not straightforward. The further the conditions of viewing and memory preservation are from optimum, the more important it is that the procedures and protections built into modern identification techniques be carefully followed. To omit them or take shortcuts increases the likelihood of false identification, which not only can put an innocent person in prison but also leave the actual offender on the street to offend again.
Preparation of a Police Lineup
The key concern when preparing a lineup is that the suspect should not stand out from the fillers. Eyewitnesses commonly believe that law enforcement has correctly placed the guilty person in the lineup and that their task is to choose this person. Any characteristic that uniquely differentiates the suspect from the fillers may be taken as indicating the identity of the offender. To ensure that the suspect does not stand out, a high-quality lineup will consist of fillers that are similar in appearance to the suspect. Lineups that meet this criterion have been shown to improve the accuracy of the decisions made by witnesses by decreasing the likelihood of a false identification. A variety of factors should be considered to ensure that the suspect does not stand out.
General Appearance
Faces should be similar in their overall shape (round, long, square, triangular) and have similar forehead area and hairline. The features of the fillers should resemble those of the suspect. No one in the lineup should have a facial expression that marks him or her as distinct from the others. Skin coloration should not vary widely.
Distinctive Features
If a witness reports a specific distinctive feature (e.g., marks, scars, tattoos) in his or her description of the perpetrator or if the suspect has a distinctive feature, all lineup members should have a distinctive feature consistent with that described by the witness or present on the suspect. If unable to locate fillers that share the consistent feature, it is better to add that distinctive feature to the fillers that do not have that feature (e.g., through photo editing software) rather than obscuring the feature on all lineup members.
Clothing
Clothing should either be highly consistent across all members of the lineup or should vary widely. The clothing described by the witnesses from the original criminal event should not be worn by any member of the lineup.
Photograph Quality
Photographs should be highly similar in their general properties (e.g., color of background, source of illumination, facial shadows, contrast, clarity) and should be originals or, when using digital images, prints shown to the witness should be made directly from the digital image. Photocopies from Xerox-type copiers should not be used.
Administration of a Police Lineup
The manner in which the lineup is administered can influence the quality of the witness’s identification decision. Factors found to influence these decisions include the pre-lineup admonitions provided to witnesses, the administrator knowledge of the suspect’s identity, the manner in which the lineup members or photographs are presented to the witness, and the use of repeated lineups with the same witness.
Pre-lineup Admonitions
Instructions (i.e., pre-lineup admonitions) for witnesses generally influence the witnesses’ perception of how much evidence of identity they require before making an identification. Because witnesses tend to approach a lineup with the expectation that the police have identified the perpetrator, they often perceive that their duty is to pick out the perpetrator rather than to evaluate the lineup to determine if the perpetrator is present. Statements made to the witness prior to viewing a lineup have been demonstrated to further exacerbate this misperception of the lineup task. For example, if the witness is told, “We’ve got a guy who we think did this, and we’d like you to look at some pictures to identify him,” the witness has been given information that the police think they have apprehended the perpetrator and also that the witness’s task is to identify the one person among those displayed whom the police believe is guilty. As a result, instructions have been developed to produce an unbiased context for the identification process. Instructions that inform the witness that the perpetrator “may or may not” be in the lineup and that the investigation will continue regardless of their identification decision have been shown to decrease the witness’s expectation that the witness should identify someone from the lineup and reduces the likelihood of the witness identifying a lineup member. In contrast, instructions that inform the witness that the perpetrator, if present, may have changed his or her appearance increase the likelihood of the witness identifying someone.
Administrator Knowledge
Law enforcement agents with knowledge of the suspect’s identity can intentionally and inadvertently influence a witness’s decision when viewing a lineup. Witnesses viewing a lineup administered by this knowledgeable administrator may look to the administrator for cues of the suspect’s identity, even when those cues are not being provided by the administrator, thereby making the witness more likely to identify someone even if the suspect is not the perpetrator. To avoid this, all communication regarding the identification procedure from making the appointment to its actual implementation should be made by law enforcement agents who are blind to the suspect’s identity.
Lineup Presentation Format
Lineups are typically presented in some version of a simultaneous or sequential format. Simultaneous lineups involve the presentation of all lineup members to the witness at the same time with the witness being asked to determine whether any of the members is the perpetrator. Sequential lineups require the presentation of lineup members one at a time with the witness required to make a determination of whether the specific individual the witness is viewing at that time is or is not the perpetrator before being presented the next lineup member. Sequential presentation leads to a reduction in identification rates whether or not the offender is present. Overall, the accuracy of identification decisions in sequential lineups is sometimes equal to those from simultaneous lineups but not superior.
Repeated Identification Procedures and Memory Contamination
A common finding in the memory literature is the relative ease with which memories of past events can be changed by new information an individual encounters. This phenomenon is referred to as memory contamination. One source of memory contamination is the repeated presentation of a suspect to a witness across multiple identification procedures. Identifications made by witnesses participating in two or more identification procedures containing the same suspect are less likely to be accurate. Another source of memory contamination is postdecision feedback provided to witnesses regarding whether or not they identified the suspect. No information about witness performance should be given to witnesses by law enforcement or anyone else.
Documentation of Confidence in Identification Decision
When assessed immediately after the identification decision, a witness’s confidence in his or her decision can be a valuable indicator of the likely accuracy of that identification. Because of the ease with which witness confidence can be manipulated, certainty statements provided by a witness at any time other than immediately after the identification decision are unreliable indicators of accuracy.
Current Recommendations for Conducting Police Lineups
Evidence-based recommendations for creating and administering lineups have been specified in many policy statements, including those produced by the U.S. Department of Justice, the International Association of Chiefs of Police, the Innocence Project, the National Academy of Sciences, and various state prosecuting attorney and law enforcement organizations (e.g., Washington Association of Prosecuting Attorneys, Law Enforcement Management Institute of Texas). Although specific recommendations may vary across these organizations’ policies, four core recommendations are consistently found.
Lineup Composition
Lineup composition refers to the quality of the fillers selected for the police lineup. The suspect should not stand out among the fillers. Fillers should be selected based on their physical similarity to the suspect and should reflect the descriptions given by witnesses, providing they were clear, specific, and in agreement.
Pre-lineup Admonitions
Pre-lineup admonitions refer to the instructions provided to the witness prior to participating in the police lineup. To decrease the likelihood of a false identification, this recommendation states that witnesses should be informed that the perpetrator may or may not be in the lineup, that they are not required to make an identification, that it is just as important to exclude innocent individuals as it is to identify the perpetrator, and that the investigation will continue regardless of the witness’s decision.
Blind Administration
Blind administration occurs when the law enforcement agent administering the lineup does not know which individual in the lineup is the suspect. To decrease the potential for administrators to intentionally or unintentionally influence a witness’s decision, this recommendation states that the law enforcement agent presenting the lineup to the witness should not have knowledge of which individual is the suspect.
Documentation
Documentation refers to the extent to which a complete record of the lineup procedures and the witness’s decision are produced. To maximize the quality of the evidence collected from the witness and decrease the potential for future information to contaminate the investigator’s and witness’s recollection of the lineup procedure and witness’s decision, this recommendation states that law enforcement should produce a complete record of the lineup including the individuals or photographs shown to the witness, the instructions provided, any statements made to the witness during or after the lineup, and any statements made by the witness during or after the lineup including a statement clarifying the witness’s certainty in his or her identification decision. All identification procedures should be video recorded so as to show the administrator, witness, the identification materials (e.g., photos, forms), and a clear view of the surface on which the materials are placed.
Law Enforcement Practice and the Implementation of Recommendations
Various state and municipal law enforcement agencies have adopted aspects of the recommendations. Training in their implementation appears to have lagged considerably behind the formal adoption of policy, and it is not at all clear whether law enforcement agencies effectively monitor the compliance of their investigators with the new protocols.
References:
- Carlson, C. A., & Carlson, M. A. (2014). An evaluation of lineup presentation, weapon presence, and a distinctive feature using ROC analysis. Journal of Applied Research in Memory and Cognition, 3, 45–53. doi:10.1016/j.jarmac.2014.03.004
- Fitzgerald, R. J., Price, H. L., Oriet, C., & Charman, S. D. (2013). The effect of suspect–filler similarity on eyewitness identification decisions: A meta-analysis. Psychology, Public Policy, and Law, 19, 151–164. doi:10.1037/a0030618
- International Association of Chiefs of Police. (2010). Showups, photographic identifications, and lineups. Alexandria, VA: IACP National Law Enforcement Policy Center.
- National Research Council of the National Academy of Sciences. (2014). Identifying the culprit: Assessing eyewitness identification. Washington, DC: The National Academies Press.
- Ross, S. J., Malpass, R. S., & Tredoux, C. G. (2013). Evaluating eyewitness testimony of adults. In I. B. Weiner & R. K. Otto (Eds.), The handbook of forensic psychology (4th ed., pp. 513–559). Hoboken, NJ: Wiley.
- Technical Working Group for Eyewitness Evidence. (1999). Eyewitness evidence: A guide for law enforcement. Washington, DC: U.S. Department of Justice, Office of Justice Programs.
- Wixted, J. T., Mickes, L., Clark, S. E., Gronlund, S. D., & Roediger, H. L. (2015). Initial eyewitness confidence reliably predicts eyewitness identification accuracy. American Psychologist, 70, 515–526. doi:10.1037/ a0039510