Can police lineups be trusted?
Although the method has long been used to identify alleged criminals, recent studies, past convictions overturned by DNA evidence and, of course, the Duke men's lacrosse rape scandal have led many to question the reliability of eye-witness identification.
Experts have noted that when devised properly, lineups can be an important tool for investigators. Neil Vidmar, Russell M. Robinson II professor of law and professor of psychology, explained that a good police lineup involves several precautions.
"I am totally sympathetic to the problems that police have with trying to identify suspects," he said. "The problem is that there is proof beyond a reasonable doubt and there is real concern that with a bad lineup procedure, people may be tagged as guilty persons when in fact they are not."
Typically, a witness will stand with an officer as several suspects are asked to turn to the front and side. "Fillers," or people included in the lineup who are known to be innocent, are often used as a precaution against eyewitnesses with poor memories.
To avoid unintended bias, it is standard practice to to use a lineup with "actual, plausible alternatives to the suspect," Vidmar said. If a witness described the perpetrator as tall, for example, use of a lineup with short suspects would be unfair to a tall suspect.
Experts have also recommended using a double-blind, where the accompanying officer is unaware of the main suspect's identity.
"Even subtle cues can influence the choices that someone makes," Vidmar said. "Many police departments have changed their procedures to avoid those kinds of problems-but not all."
In addition to using a double-blind, several states have switched to a new sequential lineup method where each suspect is shown individually to the witness. The method has yet to be adopted in North Carolina but has been recommended by commissions.
But a recent study conducted in Illinois found that the new strategy is not necessarily more effective. The study was recommended by the Governor's Commission on Capital Punishment in 2002, after several death row inmates were exonerated through DNA evidence.
The experiment, run by the Chicago Police Department, found that sequential lineups were less accurate than the traditional ones.
The correct suspect was chosen 45 percent of the time when a sequential lineup was used, and 60 percent of the time with the simultaneous lineup.
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Legal experts, however, have called the study's methodology into question.
Gary Wells, a professor of psychology at Iowa State University, found that fewer innocent people were chosen with sequential lineups than with the simultaneous method.
"The problem with [the Illinois] study is that they manipulated two variables at once," he said. "Every time they did their sort of simultaneous procedure... it was administered by the case detective."
He added that the sequential procedure, by comparison, was used with a double blind.
"It may be that the difference that they're observing is that in one case the detective is influencing the witness and in the other case not," Wells said. "What was missing here was a condition in which they used the traditional simultaneous presentation, but that they did it in a double-blind fashion."
Another alternative to live, in-person lineups has been the use of photographic lineups.
"Sometimes, it is difficult to find the person.... So you have to use photos when you have something like that," Vidmar said.
In the lacrosse case, a photographic lineup was used. According to a prosecutor's report obtained by Newsweek, the alleged victim was asked to identify the suspects using a PowerPoint presentation with photographs of the 46 team members.
Sophomores Collin Finnerty and Reade Seligmann were indicted after being selected with "100 percent certainty"-according to the alleged victim-from the lineup.
A third team member was also identified and may be indicted at the next grand jury meeting May 1.
In the lacrosse scandal, defense lawyers have noted that the absence of fillers from the lineup could call the identifications into question.
Vidmar declined to comment on the lacrosse case but noted that live and photographic lineups each have advantages and disadvantages.
A problem with live lineups, he noted, is that the behavior of suspects-nervousness, for example-may sometimes influence a witness's identification, yet that suspect may be innocent.
But photographic lineups may also have some drawbacks.
"If it's a color photograph, even then it's one-dimensional and front along. When they do a live lineup, they are faced front on, turn right, turn left, and that makes a difference," Vidmar said.
Wells noted that due to the absence of fillers, additional evidence would be needed to support the lacrosse team lineup identifications.
"I could pick someone who is a plausible person, and I wasn't even there. There's no sort of internal control in this to find out about her credibility," he said. "It doesn't mean that she's wrong-it means that there needs to be some pretty good corroborating evidence."