Empirical Assessment of Fairness of Police Lineups
A witness saw a robber in the dark for a few seconds. Six months later the eyewitness identified the defendant from a 6-person photographic lineup.
To test the lineup used in this case, Research Design Associates researchers presented 40 people (unfamiliar with the suspect) with a description of the suspect. In a fair 6-person lineup, each of the photographs is expected to be chosen 1/6 or 17% of the time. The photograph of the defendant was chosen 85% of the time. The defendant in the lineup was the only one that matched the description. The lineup photo array was biased.
Statistical tests confirmed the lineup was biased: the chance that the lineup was fair was less than one in a million. Given the empirical lineup evidence, the trial judge excluded the lineup identification from the trial.
Rather than just relying on the eyewitness description alone, the mixed method design allowed for an empirical assessment of the police lineup improving the legal decision-making.