Protecting the Innocent: Eyewitness Identification

Source: Matthew Sharps

The accurate identification of the perpetrators of crimes presents a critical psychological problem for law enforcement and the criminal justice system. Much research has shown that the single greatest influence on wrongful convictions may lie in the realm of inaccurate eyewitness accounts. Therefore, eyewitness identification procedures are of paramount importance.

As we’ve seen in previous posts here, many facets of the eyewitness process are not amenable to intervention on the part of investigators. These elements are typically called estimator variables. They lie in three realms: situational variables (for example, the relative darkness of a scene described by an eyewitness); target variables (these have nothing to do with “targeting” the individuals involved; rather, this variable class refers to what the given witness perceives, including the physical characteristics of the individuals described); and witness variables, having to do with personal characteristics of the given witness. For example, does the witness have any level of visual impairment? If so, was the witness wearing his or her eyeglasses at the time, or were the glasses perhaps sunglasses? How old is the witness? Dark lenses may have a relatively strong deleterious effect on the eyewitness powers of older persons since, through the course of normal human aging, cross-ocular light transmission diminishes substantially. These are examples of estimator variables of the witness type, and, as we’ve just seen, these variables can interact with each other significantly.

In the aftermath of a crime, little can be done to ameliorate the potential negative influence of estimator variables on eyewitness performance. Yet there is another class of variables—system variables—which are or can be controlled by the justice system. If administered properly, the procedures involved can improve the probative value of eyewitness evidence (e.g., Wells et al., 2006). If not, the results can be catastrophic, especially for the wrongly accused.

The estimator/system classification structure is not perfect. System and estimator variables can interact, and system variables can sometimes actually be estimator variables as well (but not the other way around). Other problems emerge as well: Cross-racial identifications, for example, fall under both witness and target variables since the races of the witness and the “target” are functionally intertwined in such cases. However, as a general rule, it is important to keep the broad distinction between estimator and system variables in mind. Generally, you can do nothing about the former, but you have a lot of influence on the latter.

This is important considering how suspects are generally identified by eyewitnesses, both in lineups and field identification procedures. This post is the first in our series on these issues.

The most important eyewitness elicitation procedures are those of lineups and of field identification procedures. We will deal with lineups and their administration in the next Forensic Views; for the present, we will discuss field identification procedures or showups. These procedures are well worth some serious discussion.

As many readers know, a “showup” is a procedure in which witnesses are brought to view a suspect, frequently in the field, at or near the scene of the given crime (hence the more formal term “field identification procedure”). In comparison with lineups, showups present terrible potential problems for the accused and, as we will see in our next Forensic View, for the criminal justice system as well.

Showups cannot be condemned out of hand. Sometimes they’re necessary; for example, if officers are chasing an armed murderer who may slaughter additional victims in the immediate future, it’s a very good idea for those officers to be reasonably sure that they’ve arrested the right person immediately. If they’ve got the murderer, great, but if they’ve accidentally apprehended the wrong person instead, they need to get back to the search for the killer before anyone else is massacred.

Under these circumstances, a properly documented showup would probably be seen as reasonably appropriate by many reasonable people. However, under less urgent conditions, the showup is much harder to justify. Over two decades ago, the late Attorney General Janet Reno convened a working group under the aegis of the National Institute of Justice to review eyewitness procedures (United States Department of Justice, 1999). General Reno was known for her strongly conservative approach to justice and to law enforcement, yet she and her NIJ group still held that showups are prone to an “inherent suggestiveness” and that they are properly used only “when circumstances require the prompt display of a single suspect to a witness.” Such a single suspect, being the only alternative on display, may result in an incorrect identification on that basis alone; witnesses have nobody else to choose from.

The showup is especially problematic when there are multiple witnesses. Most law enforcement officials are aware of the need to keep witnesses scrupulously apart, but until they are separated, they may very well influence each other’s memories of the events of a given crime. The Reno group’s recommendation was that, especially under such circumstances, witnesses should probably be subjected to other identification procedures as well (USDOJ, 1999, pg. 27).

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Given that every time a witness engages in an identification procedure, there is the possibility of contamination of the identification from that witness’s memory of the previous procedures, this may pose significant problems (Sharps, 2022); it’s not a good idea to have the same witnesses see depictions of the same suspects over and over again, whatever the procedure employed. Yet the showup is so fraught with difficulty that the Reno group felt the need to reinforce its use with backup procedures, however potentially hazardous in any given case.

Showups, or field identification procedures, present only a single suspect, with no alternatives, to a given witness; one can immediately see how this might bias witnesses to incorrect identification. Yet there are a variety of critical psychological issues involved in other aspects of these procedures as well. We will take up these issues and their solutions in our next post.