In movies and television, it is one of the most dramatic moments in a courtroom drama. The witness, sitting on the stand, raises a finger and points to the suspect and calls out that they saw the defendant commit the crime. But in reality, witness accounts of events are notoriously inaccurate.

In many of the cases where a witness misidentifies an innocent person as the person who committed the crime, it is not because the witness has an axe to grind or is trying to harm an innocent person. Often, they truly believe that they are correctly remembering that person. But there are a wide variety of reasons why witness identifications can be inaccurate.

One common source of inaccuracy is a phenomenon known as “co-witness contamination.” This occurs when several people witness a crime and then talk about what they saw. So imagine that several people are in a convenience store when a robbery takes place. When the witnesses are waiting for the police to arrive after the robbery, they are likely to share their memories of the event. If one person mentions that the robber was wearing a red shirt, the other witnesses are likely to incorporate that into their description of the robber, even if they never actually saw what color his shirt was.

In the next post in this series we will look at other factors that lead to witness false identifications and look at how some courts are beginning to explicitly question the reliability of witness identifications.

Source: MSNBC, “Witness error: How mind tricks can put the innocent behind bars,” Miranda Leitsinger, Feb. 12, 2012