Eyewitness testimony, often the worst evidence a jury can rely upon, sent Willie Williams to prison more than 21 years ago. Today he walks free, thanks to the Georgia Innocence Project, which used new DNA testing to establish that he wasn't the man who raped a woman in 1985.

The victim told the jury that she was certain of Williams' guilt. Unfortunately, the jury didn't know that the certainty of an identification doesn't correlate with accuracy. Victims typically focus their attention on guns and the trauma of the moment, not on faces. And they typically believe the police officers who assure them that the "right guy" has been arrested.

The DNA evidence was marked for destruction, and it was only by happenstance that the evidence was preserved until a 2003 Georgia law required the state to maintain DNA evidence. Every state should enact a similar law to help free people like Willie Williams from their wrongful imprisonments.