Mallin was not told that her attacker might not be in the lineup or that she did not have to choose anyone if she was unsure. The photos were presented simultaneously instead of sequentially, encouraging "relative judgment" -- the tendency to pick the person who most resembles a perpetrator. Instead of recording the doubts Mallin had expressed, police made notes that suggested she had chosen Cole without hesitation.
The following day, the police did a live lineup, in which Mallin picked Cole again, reinforcing her initial misidentification. By the time of Cole's trial five months later, she confidently and convincingly identified him as her attacker, which was the only real evidence against him.
Gaulkin observes that courtroom identifications, for all their drama and emotional impact, merely recapitulate whatever errors led to an initial misidentification, hardened by feedback from police and prosecutors. He also notes that memory decays irreparably over time. According to a 2008 meta-analysis of 53 studies, memory quality falls by 50 percent after one month.
Because of these and other factors, eyewitness testimony is wrong about one-third of the time, judging from laboratory experiments, field studies and analyses of real cases. Almost all of the relevant evidence has emerged since the U.S. Supreme Court last addressed the due process implications of eyewitness testimony in 1977.
In November, the court will revisit the subject, considering whether eyewitness testimony can be suppressed when it is biased by factors other than "improper state action." However the justices rule, jurors in most cases still will have to decide not only whether eyewitnesses are honest but also whether they are telling the truth.