Troy Davis has been on death row since 1991, after being convicted and sentenced to death for the 1989 killing of Savannah police officer Mark MacPhail. All through the trial and the subsequent appeals, Davis maintained his innocence, saying he was the victim of mistaken identity.
There could be something to his claims. Davis' lawyers said in the appeal that seven of nine prosecution witnesses have recanted their trial testimony, and several new witnesses have identified or implicated a different man as the killer.
The case has gotten worldwide publicity, with death penalty opponents and such high profile names as former President Jimmy Carter, Pope Benedict XVI and Nobel Peace Prize winner Desmond Tutu expressing concern about the fairness of Davis' trial.
Georgia's state attorneys told the Supreme Court the appeal should be rejected. They argued that every court that has reviewed Davis' claims has found that he failed to establish his innocence.
The court's vote was not revealed. But Justice John Paul Stevens, writing for the majority and joined by Justices Ruth Bader Ginsburg and Stephen Breyer, said: "The substantial risk of putting an innocent man to death clearly provides an adequate justification for holding an evidentiary hearing."
Two of the court's conservatives, Justices Antonin Scalia and Clarence Thomas, dissented. Scalia wrote that the Supreme Court was sending the federal judge in Georgia on a "fool's errand" because the evidence had been reviewed and rejected at least three previous times.
Newest justice Sonia Sotomayor did not participate in the in the case. No explanation was given as to why she sat this one out.