What kind of identification is using a police line up?

What is the real-life version of a lineup? And most of all, can you count on it?

by Ellen Rosner Feig
updated May 02, 2022 ·  4min read

We've all seen lineups in movies and countless TV shows. The stern cop asks the scared woman: "Do you recognize the perpetrator, Mrs. Thompson?" and she cries into a hanky and points at the shifty-eyed guy in the little hat.
And with just that, the crime is solved! The horrible criminal puts on a striped suit, gets a tin cup, and goes to jail. While this scene makes for a good few minutes in a movie, how does a lineup really work? Why Use Lineups?

The goal of the lineup is to build crucial evidence in a criminal case. It is considered a vital element in any police investigation and comes in three different versions, the "simultaneous" lineup, the "sequential" lineup, and the "multiple-identification" lineup.

The Simultaneous Lineup

The classic, most familiar version is the simultaneous lineup. Police officials assemble the suspect and at least five "fillers" with similar physical attributes. The fillers may be chosen from those who have been suspected of similar crimes in the past. These six are then arranged in random order. The witness stands behind a one-way glass mirror, and with a district attorney and a defense attorney present, the police officer will:

1. Provide clear viewing instructions to the witness, advising that individuals may not appear as they did on the date of the crime.
2. Instruct those present at the lineup not to suggest the position or identity of the suspect.
3. Ensure that all members of the lineup perform identification actions such as speech and movement.
4. Avoid saying something to the witness that may influence his/her selection.
5. If identification is made, avoid reporting to the witness any information regarding the selected individual before making a statement of certainty.
6. Ask the victim to state, aloud, how certain he/she is of identification.
7. Record the identification results in writing and by photo or video.
8. Instruct the witness not to discuss the lineup with any other witnesses or with the media.

The Sequential Lineup

In a "sequential" lineup, individuals, including the suspect, are viewed one at a time in random order. The witness will be afforded as much time as needed to decide on moving on to the next person.

In a sequential lineup, all members of the line-up are presented to the victim, even if the victim has already made an identification. Recent Department of Justice studies have found that witnesses are more likely to identify the guilty person in a sequential lineup due to the lower risk of comparison between individuals.

The Multiple-Identification Lineup

Finally, with the help of psychologists, the "multiple-identification" lineup was developed, a version found by one recent study to provide the best evidence for prosecutors.

In this type, the witness identifies the perpetrator from photos that are presented sequentially. First, the witness only sees the suspect's face; once the faces are looked at, the witness is given sequential photos of the body or vocal tape recordings. The hope is that this type of multiple lineup will ensure greater accuracy in identification.

Do They Really Work?

So, once you understand how lineups work, the question remains: are they reliable?

The credibility of police lineups is a hotly debated topic. Many lineups get "tainted with alarming frequency," meaning a police officer will push a victim to identify the person considered the subject.

According to a study by the Innocence Project, a group that uses DNA testing to right wrongful convictions, mistaken identification from lineups accounted for 60 of the 82 exonerations. States across the country have changed their lineup regulations to add a measure of reliability to an eyewitness identification. These changes include:

• The person conducting the lineup should be someone other than the primary investigator on the case. A May 2005 study by the National Science Foundation found that many investigators unwittingly influence a witness' choice in a lineup through body language and eye contact.
• The witness should be advised before the lineup that the perpetrator may not be among those in the lineup.
• The lineup should be comprised in such a way that the suspect does not stand out.
• When possible, the sequential lineup should be used. Psychologist Gary L. Wells, Ph.D., a distinguished Professor of Psychology at Iowa State University, has spent years studying the use of lineups, both in person and through photos. His research has shown that the use of the sequential technique cuts down on mistaken identifications.

While it might not be the most failsafe tool in the criminal investigation handbook, police lineups aren't going away any time soon. With new developments in methodology from other disciplines, when the weeping lady points out the bad guy, she'll have better odds of picking the right one.

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