The high court today ordered a federal judge in Georgia to determine whether there is evidence that proves Davis did not kill a police officer in 1991.
Davis was condemned to death for that murder, but supporters have argued for a new trial after several witnesses took back their testimony. Davis' supporters include former President Jimmy Carter and Pope Benedict XVI.
Justice John Paul Stevens said that the risk of putting an innocent man to death "provides adequate justification" for an evidentiary hearing.
Defense lawyers had appealed to the Supreme Court after a federal court denied a new trial request in April.