Many eyewitnesses have absolutely no reason to lie and honestly believe that they are telling the truth. The eyewitness may simply have been a bystander at the scene of the crime. The police are conducting an investigation and they want to know what happened – and if the eyewitness saw the alleged perpetrator.
In court, because the eyewitness typically does not have a reason to lie about what they saw, their testimony will often carry a lot of weight. And the eyewitness themselves may believe that what they’re saying is accurate. But studies have found that eyewitnesses often get it wrong and that their accuracy is not nearly as consistent as people assume.
How do we know witnesses are wrong?
This problem has come to light in the last few decades, in large part because of DNA evidence. Tools for analyzing this evidence have gotten better, as well as collection efforts.
DNA evidence is also unique to each individual. In other words, it can prove unequivocally that someone was not the perpetrator of a crime because the DNA evidence isn’t a match – or it is a match with a different suspect.
When groups like the Innocence Project look at the exonerations coming from DNA evidence – people who are being released from prison after being wrongfully convicted – they find that inaccurate eyewitness testimony plays a large role. In many of these false convictions, the reason is that the eyewitness told an incorrect story about the event or identified the wrong perpetrator. Their memory is not nearly as accurate as even the eyewitnesses themselves believe.
This helps to show one of the complications with criminal cases and why false convictions could occur. It also underscores why it’s so important for those facing charges to know what legal options they have.