It has been found that when an eyewitness testimony is provided as evidence in a criminal court case, it is more likely to result in a conviction (Visher, 1987), in fact, 77,000 people per year are charged with crimes solely based on eyewitness evidence (Goldstein, Chance & Schneller, 1989). A study conducted by Loftus (1974) found an alarming 54% swing from a non-guilty verdict, to that of guilty within the same case simply through the introduction of an eyewitness testimony. Such findings clearly demonstrate the potency of eyewitness testimony, and support the theory that jurors tend to over believe, or at least weigh heavily on such evidence (Kennedy & Haygood, 1992).
The legal system has long used eyewitness testimonies for developing leads, convicting criminals and exonerating the innocent, yet even honest and well-meaning witnesses can make errors. Thousands of innocent people are wrongfully convicted every year (Buckhout, 1974), and as a study by Brandon & Davies (1973) found, 74% of wrongful convictions resulted from evidence provided by eyewitnesses.
Such findings have led many psychologists and legal scholars to claim that eyewitness testimonies should be used with great caution, if at all. Houts (1956), for example, stated, "Eyewitness identification is the most unreliable form of evidence and causes more miscarriages of justice than any other method of proof" (p. 10-11).
A vast quantity of research spanning several decades has focused on the accuracy of recall of eyewitness testimonies, with somewhat uninspiring results. Studies have shown that many factors can negatively affect a witness' recall, for example, the perpetrator being racially different to the eyewitness (Brigham & Malpass, 1985); the fear/anxiety caused by the presence of a weapon (Loftus, Loftus & Messo, 1987); and the impact of having previously seen someone's face in a different context (Memon & Wright, 1999).