New Study on DNA & Wrongful Convictions

STUDIES: What Percent of Convictions Are Mistaken?

Posted: July 02, 2012

In June, the National Institute of Justice released the results of a study to determine how often modern DNA testing of evidence from older cases confirms the original conviction.  The study, conducted by the Urban Institute in Washington, D.C, tested DNA evidence that had been retained in homicide and sexual assault convictions that occurred between 1973 and 1987 in Virginia.  Among the homicides, there were not enough cases in which DNA would be determinative of guilt to make statistically reliable conclusions about mistakes.  In cases of sexual assault, DNA testing revealed that in 8-15% of the convictions, the convicted offenders were eliminated as the source of questioned evidence and that elimination was supportive of an exoneration.  The report concluded, “Even our most conservative estimate suggests that 8 percent (or more) of sexual assault convictions in a 15-year period may have been wrongful. That means hundreds, if not more than a thousand, convicted offenders may have been wrongfully convicted. That also means hundreds (if not more) victims have not received the just result, as previously believed. Therefore, whether the true rate of potential wrongful conviction is 8 percent or 15 percent in sexual assaults in Virginia between 1973 and 1987 is not as important as the finding that these results require a strong and coordinated policy response."

from The Death Penalty Information Center