|Eyewitness Identification Research Laboratory
At the University of Texas at El Paso
Lineup Fairness as Procedural Safeguard.
Including additional persons in the lineup along with the suspect is a safeguard against false identification. In order for the safeguard to be effective these two closely related conditions should be achieved:
• The fillers should be good alternatives to the suspect, and
• The suspect should not stand out from the other lineup members.
If the first is achieved the second should follow. From these conditions others can be derived. For example, the suspect in a lineup should not be identifiable by non-witnesses or by persons who know (remember) only his general description - because the fillers will have been chosen in the first place because they are similar to the suspect. If non-witnesses can reliably choose the suspect from a lineup, then the lineup violates the principle that the suspect should not stand out from the fillers. Instead it is biased towards the suspect, fails as a safeguard, and is unfair.
Compared with showing a witness the suspect alone (a "show-up"), placing a suspect in a lineup reveals some important possibilities:
* If a witness identifies the suspect, surmounting the higher bar instituted by the safeguard, the case for the prosecution is markedly strengthened. But only if the lineup was fair: if it's a biased lineup it's not possible to interpret the meaning of the identification.
* If a witness identifies someone other than the suspect, the suspect may be eliminated from investigation, and/or the investigation may be redirected towards other possible suspects. Alternatively, the quality of the witness’ evidence (memory) may be re-evaluated.
* If an identification is not made the witness may not have a very good memory and/or may be unwilling to identify someone they’re not sure of. Alternatively, the eyewitness may have a good memory and know that the offender is not in the lineup.
* A properly constructed lineup protects an innocent suspect from a witness with little visual identification information who nonetheless feels constrained to identify someone, and at the same time allows a witness with good visual identification information to identify the offender if he is present.
Of course all of these points are based on the assumption that the fillers are good alternatives to the suspect, and its corollary that the suspect does not stand out from the fillers. When you think about it, this is obvious. If the suspect stands out, then it would be easy for a witness with no memory of the offender at all to know which person in the lineup is the investigator's suspect, even if he were innocent!
The evidence from research on these issues supports the conclusion that properly constructed lineups impose little or no handicap on the identification of the guilty, while offering substantial protection against false identification of innocent suspects.