In many criminal cases, eyewitness testimony is fundamental to the outcome. Whether the person identified a suspect in a lineup or pointed to the defendant in court, eyewitnesses are often taken to be inherently credible. After all, they saw it with their own eyes.
However, eyewitnesses don’t have to be lying to be wrong. The truth is that human memory is malleable and open to contamination.
A recent study found that people’s memories are the most accurate the first time they try to recall an event, especially if they are confident in their memory. However, the more times they told the story and the more time that passed, the more contaminated the memory was likely to become. This contamination could be the result of suggestion, for example, or of new information or confirmation bias.
How often are eyewitnesses wrong?
That may be impossible to know. What we do know is that eyewitness testimony was presented in 70% of 349 wrongful convictions that were later overturned thanks to DNA evidence. There have also been a number of high-profile cases recently where eyewitnesses have been later proven wrong.
A wrongful conviction is the worst outcome we can have in the criminal justice system. Not only does the wrong person go to prison but, in many cases, the guilty party remains free. The victim gets no justice at all, and an innocent person loses their freedom. Confidence in the system is diminished.
What can be done to prevent eyewitness mistakes?
There are a number of techniques the police can use to catch people before their memories change and to prevent contamination, especially by suggestion. For example:
- The people in the lineup or photo array should match the witness’s initial description, as opposed to matching the police’s current suspect.
- Suspect lineups should be double-blind (neither the eyewitness nor the officers involved should know who the suspect is). This is true for live lineups and photo arrays. This prevents officers from accidentally “suggesting” who the eyewitness should pick.
- The eyewitness needs to be told that the guilty person may not be in the lineup, and that they should not choose someone unless they are confident. Otherwise, the eyewitness may feel pressure to choose the most likely person in the lineup or photo array.
- When the eyewitness does identify someone, the officer should ask them how confident they are. It may be helpful to have the eyewitness give a confidence rating for each member of the lineup or photo array.
If you have been charged with a crime, a dedicated criminal defense attorney can help by going the extra mile to explore whether an eyewitness ID was suggestive or otherwise likely to produce an inaccurate memory.