In Eyewitness ID: Part I we talked about mistakes in eyewitness identification that led to the wrongful conviction of Ronald Cotton; in Part II, we talked about the composite sketch. In Part III we examine the old police stand-by, the line-up, and where to begin in investigating an eyewitness identification case.
A line-up can be either a "photo montage" of various suspects or can be a live line-up. Normally, a "show-up" with only one suspect is considered unnecessarily suggestive and is ripe for challenge. When investigating a one-on-one show-up case, look at the reasons given for the one-on-one show-up. Police will normally cite some sort of exigency, so the investigator will be looking for whether that exigency outweighed the risk of irreparable damage done to the eyewitness by the unnecessarily suggestive identification process.
A good place to start with a line-up is to look closely at the police procedures used in the line-up; the facts that the defense investigator develops regarding the police procedures can be important at both the motion to suppress the identification and at trial to assist the jury in understanding why a false identification can occur.
A suitable beginning point is to examine the United States Department of Justice's manual, "Eyewitness Evidence: A Guide for Law Enforcement", and its companion, "Eyewitness Evidence: A Trainer's Manual for Law Enforcement." Both manuals contain detailed procedures for conducting line-up procedures including: composing the line-up with fillers, using fillers that meet the perpetrator's description, positioning suspects randomly, providing detailed instructions to the witness, avoiding giving the witness verbal or non-verbal clues, and avoiding making statements of reassurance to the witness after he/she has made a choice of suspects. These two law enforcement guides will give the investigator a good starting point in evaluating whether the line-up comports with proper police procedure.
As part of the investigation, determine what type of line-up was used. There are simultaneous and sequential line-ups: in the simultaneous line-up, all suspects are viewed at once while in the sequential, the suspects are viewed one at a time. There is a large body of research on whether the sequential line-up produces more accurate results than the simultaneous line-up. For a very informative journal from the police perspective, see Police Lineups: Making Eyewitness Identification More Reliable.
The Innocence Project proposes a number of reforms for eyewitness identification including double-blind administration of line-ups where neither the officer nor the witness knows who the suspect is in the line-up. Other proposals for eyewitness identification reform by the Innocence Project include making line-up compositions carefully to have fillers more closely resemble suspects, instructions to the witness including that the perpetrator may not be in the line-up, a confidence statement from the witness, and a recording by police of the line-up procedure and witness identification.
Given that eyewitness misidentification has contributed to more than 75% of wrongful convictions overturned with DNA testing, look closely at the procedures used in your line-up cases as part of your total investigation into the eyewitness identification.