For the court, it often feels easy to trust an eyewitness. If they present their account to the jury, the jury can’t see any reason why they would give false testimony. They have nothing to gain. They seem honest and they appear to be relating their memories of the event accurately.
But are they? Can we trust them?
Science says that we should actually be very careful with this, as it’s striking how often these eyewitnesses get it wrong. For instance, take a look at the 350+ cases that have been overturned through the use of DNA evidence. These are cases where a person was convicted and sentenced. Only later did DNA prove that the conviction was inaccurate, and any time they served was time that a fully innocent person spent behind bars. Some of them have been on death row.
In any case, when you look at the major contributing factors in those cases, you’ll find that testimony from one or more people who witnessed the event firsthand played a role in about 70% of the cases. Most of the time, in other words, eyewitnesses testified against the wrong people. They went on the stand and convincingly told the jury that someone was guilty when they weren’t.
That may not always be intentional. Some of these witnesses may have just made mistakes. But it still shows how often this happens and how a conviction is not necessarily the end of the line — or evidence that the truth has even been discovered. The justice system is far from perfect. Those who are facing serious charges have to know about all of the legal options at their disposal.