WASHINGTON  The Supreme Court on Monday ordered a federal trial court in Georgia to consider the case of Troy Davis, who is on death row in state prison there for the 1989 murder of an off-duty police officer. The case has attracted international attention, and 27 former prosecutors and judges had filed a brief supporting Mr. Davis.

Seven of the witnesses against Mr. Davis have recanted, and several people have implicated the prosecution’s main witness as the actual killer of the officer, Mark MacPhail.

The Supreme Court’s decision was unsigned, only a paragraph long and in a number of respects highly unusual. It instructed the trial court to “receive testimony and make findings of fact” about whether new evidence clearly established Mr. Davis’s innocence. Justice Sonia Sotomayor, who joined the court this month, did not participate.

The decision set off a sharp debate between Justices John Paul Stevens and Antonin Scalia about Supreme Court procedure, the reach of a federal law meant to limit death row appeals and the proper treatment of claims of innocence.