Eyewitness identification
In eyewitness identification, in criminal law, evidence is received from a witness "who has actually seen an event and can so testify in court".
The Innocence Project states that "Eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in more than 75% of convictions overturned through DNA testing." This non-profit organization uses DNA evidence to reopen criminal convictions that were made before DNA testing was available as a tool in criminal investigations.
Even before DNA testing revealed wrongful convictions based on eyewitness identifications, courts recognized and discussed the limits of eyewitness testimony. The late U.S. Supreme Court Justice William J. Brennan, Jr. observed in 1980 that "At least since United States v. Wade, 388 U.S. 218, the Court has recognized the inherently suspect qualities of eyewitness identification evidence, and described the evidence as "notoriously unreliable", while noting that juries were highly receptive to it. Similarly, in the United Kingdom, the Criminal Law Review Committee, writing in 1971, stated that cases of mistaken identification "constitute by far the greatest cause of actual or possible wrong convictions".
Brennan said that "All the evidence points rather strikingly to the conclusion that there is almost nothing more convincing than a live human being who takes the stand, points a finger at the defendant, and says 'That's the one!'" Another commentator observed that the eyewitness identification of a person as a perpetrator was persuasive to jurors even when "far outweighed by evidence of innocence."
Causes of eyewitness error
"System variables" (police procedures)
The police procedures used to collect eyewitness evidence have been found to have strong effects on the conclusions of witnesses. Studies have identified various factors that can affect the reliability of police identification procedures as a test of eyewitness memory. These procedural mechanisms have been termed "system variables" by social scientists researching this systemic problem. "System variables are those that affect the accuracy of eyewitness identifications and over which the criminal justice system has control."Acknowledging the importance of such procedural precautions as recommended by leading eyewitness researchers, in 1999 the Department of Justice published a set of best practices for conducting police lineups.
Culprit-present versus culprit-absent lineups
One cause of inaccurate identifications results from police lineups that do not include the perpetrator of the crime. In other words, police may suspect one person of having committed a crime, although in fact it was committed by another, still unknown person, who thus is excluded from the lineup. When the actual perpetrator is not included in the lineup, research has shown that the police suspect faces a significantly heightened risk of being incorrectly identified as the culprit.According to eyewitness researchers, the most likely cause of this misidentification is what is termed the "relative judgment" process. That is, when viewing a group of photos or individuals, a witness tends to select the person who looks "most like" the perpetrator. When the actual perpetrator is not present in the lineup, the police suspect is often the person who best fits the description, hence his or her selection for the lineup.
Given the common, good faith occurrence of police lineups that do not include the actual perpetrator of a crime, other procedural measures must be undertaken to minimize the likelihood of an inaccurate identification.
Pre-lineup instructions
Researchers hypothesized that instructing the witness prior to the lineup might serve to mitigate the occurrence of error. Studies have shown that instructing a witness that the perpetrator "may or may not be present" in the lineup can dramatically reduce the likelihood that a witness will identify an innocent person."Blind" lineup administration
Eyewitness researchers know that the police lineup is, at center, a psychological experiment designed to test the ability of a witness to recall the identity of the perpetrator of a crime. As such, it is recommended that police lineups be conducted in double-blind fashion, like any scientific experiment, in order to avert the possibility that inadvertent cues from the lineup administrator will suggest the "correct" answer and thereby subvert the independent memory of the witness. The occurrence of "experimenter bias" is well documented across the sciences. Researchers recommend that police lineups be conducted by someone who is not connected to the case and is unaware of the identity of the suspect.Confidence judgement
Asking an eyewitness their confidence in their selection with a doubleblind process can improve the accuracy of eyewitness selection.Lineup structure and content
"Known innocent" fillers
Once police have identified a suspect, they will typically place that individual into either a live or photo lineup, along with a set of "fillers." Researchers and the DOJ guidelines recommend, as a preliminary matter, that the fillers be "known innocent" non-suspects. This way, if a witness selects someone other than the suspect, the unreliability of that witness's memory is revealed. The lineup procedure can serve as a test of the witness's memory, with clear "wrong" answers. If more than one suspect is included in the lineupas in the 2006 Duke University lacrosse case, for examplethen the lineup becomes tantamount to a multiple choice test with no wrong answer.Filler characteristics
"Known innocent" fillers should be selected to match the original description provided by the witness.If a neutral observer is able to select the suspect from the lineup based on the recorded description by the witnessthat is, if the suspect is the only one present who clearly fits the descriptionthen the procedure cannot be relied upon as a test of the witness's memory of the actual perpetrator. Researchers have noted that this rule is particularly important when the witness's description includes unique features, such as tattoos, scars, unusual hairstyles, etc.
Simultaneous versus sequential presentation
Researchers have also suggested that the manner in which photos or individuals chosen for a lineup are presented can be key to the reliability of an identification. Specifically, lineups should be conducted sequentially, rather than simultaneously. In other words, each member of a given lineup should be presented to a witness by himself, rather than showing a group of photos or individuals to a witness together. According to social scientists, use of this procedure will minimize the effects of the "relative judgment" process discussed above. It encourages witnesses to compare each person individually to his or her independent memory of the perpetrator.According to researchers, use of a simultaneous procedure makes it more likely that witnesses will pick the person in the group who looks the most like their memory of the perpetrator. This introduces a high risk of misidentification when the actual perpetrator is not present in the lineup. In 2006, a pilot study was conducted in Minnesota on this hypothesis. Results showed that the sequential procedure was superior as a means of improving identification accuracy and reducing the occurrence of false identifications.
"Illinois Report" controversy
In 2005, the Illinois state legislature commissioned a pilot project to test recommended reform measures intended to increase the accuracy and reliability of police identification procedures. The Chicago police department conducted the study. Its initial report purported to show that the status quo was superior to the procedures recommended by researchers to reduce false identifications. The mainstream media spotlighted the report, suggesting that three decades' worth of otherwise uncontroverted social science had been called into question.Criticism of the report and its underlying methodology soon emerged. One critic said that
"the design of the project contained so many fundamental flaws that it is fair to wonder whether its sole purpose was to inject confusion into the debate about the efficacy of sequential double-blind procedures and to thereby prevent adoption of the reforms."
Seeking information on the data and methodology underlying the report, the National Association of Criminal Defense Lawyers filed a lawsuit under the Freedom of Information Act to gain access to the unreleased information. That suit remains pending.
In July 2007, a "blue ribbon" panel of eminent psychologists, including one Nobel Laureate, released a report examining the methodology and claims of the Illinois Report. Their conclusions appeared to have confirmed concerns of the early critics. Researchers reported that the study had a basic flaw that adversely affected its scientific merit, and "guaranteed that most outcomes would be difficult or impossible to interpret." Their primary critique was that variables had been "confounded", making it impossible to draw meaningful comparisons among the methods tested.
The critics found the following:
The Illinois study compared the traditional simultaneous method of lineup presentation with the sequential double-blind method recommended by recognized researchers in the field. The traditional method is not conducted double-blind. The critics claim that the results cannot be compared because one method was not double-blind while the other was double-blind.
But This criticism ignores the fact that the mandate of the Illinois legislature was to compare the traditional method with the academic method. More significantly, as an experiment to determine whether or not sequential double-blind administration would be superior to the simultaneous methods used by most police departments, the Illinois study provides an abundance of useful data which, at this point, seems to show that neither of the methods used in that experiment is superior to the other. What it does not provide is a clear reason why, because the effect of "double-blind" was not tested for the simultaneous lineups.
The Innocence Project Lineup studies mentioned here previously were never funded, largely because the expected grant funds were withdrawn in connection with economic difficulties. A separate grant was submitted to the Department of Justice in March 2009 by the independent Urban Institute to study simultaneous/sequential lineups in police departments in Connecticut and Washington, D.C. That study had been solicited by DOJ, but was unexpectedly cancelled in August 2009 due to "a low likelihood of success." The Urban Institute is seeking other funding.