The problem isn't just driven by a few overzealous attorneys, but a legal structure that facilitates abuse. In a Minnesota Law Review article, Garrett noted that in addition to the court's blocking of DNA evidence, wrongful convictions can also happen because defense counsel failed to request DNA testing, or state investigators “concealed or misrepresented DNA evidence.” Such assaults to due process persist in large part because “neither the states nor the federal courts have adopted a straightforward right to preserve, disclose, and accurately present evidence of innocence. Compounding the problem, courts fail to ensure that defendants obtain the representation and expert assistance at trial necessary to claim innocence using DNA evidence.”

A related article on post-conviction DNA exonerations describes how forensic science plays into systemic racial disparities, especially in rape cases:

These innocence cases include a disproportionate number of minorities, for reasons that may reflect their overrepresentation among convicts in the criminal system, as well as the role of race in rape investigations.... [If] DNA exonerations represent the tip of an iceberg, then the base of the iceberg, whatever its size, may also disproportionately consist of minority convicts. This racial justice concern should only elevate our unease over how effectively our system judges innocence.

To prevent wrongful convictions, the Justice Project has called for tighter accountability rules for prosecutors. The group's recent policy review detailed rampant patterns of prosecutorial misconduct nationwide, ranging from suppressing forensic evidence to manipulating “cooperating” witnesses. And often, a culture of indifference or “protecting their own” taints the handling of misconduct cases. So at the end of the day, some crooked prosecutors may get off scot-free while winning accolades for convicting the wrong person--and we're supposed to sleep better at night.

Image: Kennedy Brewer with his mother. He recently became the first person in Mississippi to be exonerated on the basis of post-conviction DNA testing. (AP)