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The Double (Edged) Helix of DNA Evidence


There’s been a lot of fanfare recently — and in many ways, rightly so — over the over 200 people who have been exonerated by DNA evidence. Many of these people served upwards of fifteen years in prison for crimes they didn’t commit (many of them for rape or rape & murder, crimes for which DNA evidence is more likely to exist). Several were on Death Row. In many of the cases, prosecutors at first refused to perform DNA testing that could exonerate the convicted and identify the truly guilty. That these 200 are just a small fraction of the people wrongly convicted is intuitive and undeniable, especially considering a new study, published in the Columbia Law Review in January (and available on SSRN), which concretizes this intuition. As the New York Times’s Adam Liptak wrote in a column Monday about the study (behind the damned TimesSelect shield), the leading reason for the false convictions of the (mostly) men exonerated by DNA evidence were faulty eyewitness IDs and testimony, which played a role in 79% of the wrongful convictions. In several of these cases, the person who provided the faulty ID was later revealed to be the person who actually committed the crime (revealed through DNA, usually). The impact of bad eyewitness IDs, of course, is no surprise. The Innocence Project, among others, has documented the high rate of error in eyewitness IDs.

The fact that DNA has been able to exonerate these 200 people who were wrongly convicted, whether by eyewitness mis-identification or any of the other causes of wrongful convictions (including faulty forensic evidence, which, according to the Times, was involved in 55% of wrongful convictions), is no doubt good news. But the power of DNA to exonerate these people (and, often, to elucidate the identity of the real perpetrator) also presents problems for those people wrongly convicted of crimes for which there is no DNA evidence, whether because there was none to be gathered, or because the DNA has been lost. Take Troy Davis, for example, the potentially innocent man who came within 24 hours of execution in Georgia last week. As the DMI Blog notes, Davis was convicted solely on the basis of “eyewitness” testimony. Of the nine people who identified him, six have recanted, one refuses to cooperate, one was the principle alternative suspect whom others labeled as the shooter, and one contradicted the testimony made at trial. Yet, while the Georgia Board of Pardons is considering his plea for clemency, Davis’s life hangs by a thread. In large part because if indeed he is innocent, there is no DNA evidence to exonerate him, only false testimony to convict him.

At the close of his column, Liptak notes that the “era of DNA exonerations is a finite one,” since DNA is being collected and analyzed more and more on the front end of prosecutions. But that still leaves this gaping hole in cases that lack DNA evidence and where there is (potentially faulty) eyewitness testimony. DNA has delivered justice for some, but it has also obscured the need for real reform that can provide justice for greater numbers and more often.

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