Criminal Law: Trial

Eyewitness testimony, which relies on the accuracy of human memory, has an enormous impact on the outcome of a trial. Aside from smoking pistol, nothing carries as much weight with a jury as the testimony of an actual witness. The memory of witnesses is crucial not only in criminal cases but in civil cases as well--in automobile accident cases, for example, eyewitness testimony carries great weight in determining who is as fault.

It's a cliché of courtroom dramas - that moment when the witness is asked "Do you see the person who committed the crime here in this courtroom before you?" It happens in real courtrooms all the time, and to jurors, that point of the finger by a confident eyewitness is about as damning as evidence can get.
But there is one type of evidence that's even more persuasive: DNA. There have been 233 people exonerated by DNA in this country, and now a stunning pattern has emerged: more than three quarters of them were sent to prison at least in part because an eyewitness pointed a finger - an eyewitness we now know was wrong.

The freeing of James Calvin Tillman after 18 years of wrongful imprisonment contains a lesson that has been told and retold thousands of times: Eyewitness identification of strangers is unreliable.

One of the things that we know about memory is that when you experience something extremely upsetting or traumatic, you don't just record the event like a video tape machine would work, the process is much more complex and what's happening is you're taking in bits and pieces of the experience, you're storing some information about the experience, but it's not some indelible image that you're going to be able to dig out and replay later on.

In a presentation sponsored by the Stanford Journal of Legal Studies, George Fisher placed Barbara Tversky’s research on memory fallibility into the context of police investigations and jury verdicts, discussing the relevance of such research to our system of justice.

Our eyes deceive us. Social scientists have insisted for decades that our eyewitness-identification process is unreliable at best and can be the cause of grievous injustice. A study published last month by Gary Wells and Deah Quinlivan in Law and Human Behavior, the journal of the American Psychology-Law Society, reveals just how often those injustices occur: of the more than 230 people in the United States who were wrongfully convicted and later exonerated by DNA evidence, approximately 77 percent involved cases of mistaken eyewitness identification, more than any other single factor.