The case of Troy Anthony Davis took another extraordinary turn on Monday as the U.S. Supreme Court ordered a federal district judge to hear testimony on the death row inmate's claims that he did not murder a Savannah, Ga., police officer.

Justice Antonin Scalia said in a dissent that the high court hadn't made a similar move in nearly 50 years.

The decision was welcomed by supporters of Davis, who for years have claimed that prosecution witnesses have recanted their testimony from the 1991 trial in which a jury condemned Davis to die for the 1989 killing of Officer Mark Allen MacPhail.

Georgia Attorney General Thurbert E. Baker, whose office has fought Davis' efforts to gain relief, issued a measured response to the ruling, saying simply that he hoped the hearing would resolve doubts about the case.

The timing of the decision was unexpected, as many assumed after the high court failed to act on Davis' filing before the Court recessed in June that it wouldn't take up the matter until a new term started in October. "I didn't think it was going to be this kind of Monday," said Jason C. Ewart of Arnold & Porter's Washington, D.C., office, who has been representing Davis.

Davis' lawyers took an unusual path to Monday's success -- convincing the nation's highest court to view favorably a petition for an writ of habeas corpus filed directly with the Supreme Court, rather than the lower courts.

Davis' backers have pointed to post-trial affidavits they say represent the recantations of seven of the prosecution's nine trial witnesses, as well as claims that another prosecution witness had confessed to the crime. They had been unsuccessful in obtaining relief for Davis before the State Board of Pardons and Paroles, the Supreme Court of Georgia and the 11th U.S. Circuit Court of Appeals, although they have managed to keep Davis alive long past his first execution date in 2007, and through a changing of the guard at the Chatham County district attorney's office. The most recent petition filed with the U.S. Supreme Court was considered a long shot, not just because such petitions rarely succeed at the high court but because the Supreme Court had previously rejected bids for help from Davis.

In its ruling Monday (pdf), the nation's highest court transferred Davis' request for a writ of habeas corpus to the Southern District of Georgia for the district court's "hearing and determination." The Court said the district judge "should receive testimony and make findings of fact as to whether evidence that could not have been obtained at the time of the trial clearly establishes petitioner's innocence."

It's not clear how each justice voted. The Court's newest member, Sonia Sotomayor, did not participate in the Court's decision. Three of the Court's other justices -- Chief Justice John G. Roberts Jr. and Justices Anthony M. Kennedy and Samuel A. Alito Jr. -- signed on to neither Scalia's dissent nor a concurring opinion written by Justice John Paul Stevens.

A press release issued by Amnesty International cheered the decision as a 6-2 ruling, which presumes that Roberts, Kennedy and Alito must have voted in favor of the Court's ruling since they did not signal otherwise. But a report by Lyle Denniston on SCOTUSblog said it was unclear how Roberts, Kennedy and Alito had voted, allowing that at least two of them must have agreed to the result in order to form a majority of the eight justices participating.

Appended to the Court's brief explanation of its ruling was a spirited exchange between Scalia and Stevens, whose concurrence was written to respond to Scalia's critique (pdf) of the Court's decision.

Joined by Justice Clarence Thomas, a Pin Point, Ga., native who has close ties to Savannah, Scalia wrote that the Court was sending the district judge "on a fool's errand."

"The Court proceeds down this path even though every judicial and executive body that has examined petitioner's stale claim of innocence has been unpersuaded, and (to make matters worst) even though it would be impossible for the District Court to grant any relief," wrote Scalia.

"Far from demonstrating, as this Court's Rule 20.4(a) requires, 'exceptional circumstances' that 'warrant the exercise of the Court's discretionary powers,' petitioner's claim is a sure loser. Transferring his petition to the District Court is a confusing exercise that can serve no purpose except to delay the State's execution of its lawful criminal judgment."

Scalia wrote that even if the district court were to be persuaded by Davis' affidavits, it would have no power to grant him relief. Federal death penalty law -- specifically, 28 U.S.C. § 2254(d)(1) -- forbids the issuance of a writ of habeas corpus on a claim that was argued on the merits in state court unless the state court's decision was contrary to clearly established federal law, wrote Scalia.

He noted that the Supreme Court of Georgia had rejected Davis' claim of innocence when it denied his extraordinary motion for a new trial, a decision he said "most assuredly was not" contrary to clearly established federal law.

"This Court has never held that the Constitution forbids the execution of a convicted defendant who has had a full and fair trial but is later able to convince a habeas court that he is 'actually' innocent," wrote Scalia. "Quite to the contrary, we have repeatedly left that question unresolved, while expressing considerable doubt that any claim based on alleged 'actual innocence' is constitutionally cognizable. ... A state court cannot possibly have contravened, or even unreasonably applied, 'clearly established Federal law, as determined by the Supreme Court of the United States,' by rejecting a type of claim that the Supreme Court has not once accepted as valid."

Scalia wrote that he doesn't think the district judge will know what to do with the Court's decision. "If this Court thinks it possible that capital convictions obtained in full compliance with law can never be final, but are always subject to being set aside by federal courts for the reason of 'actual innocence,'" wrote Scalia, "it should set this case on our own docket so that we can (if necessary) resolve that question."

Justices Ruth Bader Ginsburg and Stephen G. Breyer joined Stevens' response to Scalia.

"The substantial risk of putting an innocent man to death clearly provides an adequate justification for holding an evidentiary hearing," wrote Stevens. And Stevens said the court's transfer of the case to the district court was by no means a fool's errand.

Stevens said there are several ways the district court might get around 28 U.S.C. § 2254(d)(1).

Stevens made two suggestions Scalia dismissed in a footnote as "not warrant[ing] response" -- that the district judge might find that the statutory requirement doesn't apply, or doesn't apply as rigidly, to an original habeas petition such as Davis', or that the actual innocence claims might be exempted from the rule.

"Even if the court finds that §2254(d)(1) applies in full," wrote Stevens, "it is arguably unconstitutional to the extent it bars relief for a death row inmate who has established his innocence. Alternatively, the court may find in such a case that the statute's text is satisfied, because decisions of this Court clearly support the proposition that it 'would be an atrocious violation of our Constitution and the principles upon which it is based' to execute an innocent person."

Stevens wrote that Scalia's approach would treat robust showings of innocence the same way it treats claims of minor procedural errors. "But imagine a petitioner in Davis's situation who possesses new evidence conclusively and definitively proving, beyond any scintilla of doubt, that he is an innocent man," concluded Stevens. "The dissent's reasoning would allow such a petitioner to be put to death nonetheless. The Court correctly refuses to endorse such reasoning."

Ewart, Davis' lawyer, said his team was happy Stevens focused on the issue of innocence, rather than procedural barriers. "We hope that this turns the tide to make the discussion a little more substantive," he said.

The decision was a loss for Attorney General Baker, who is running for the Democratic nomination for governor.

In a statement issued through his spokesman, Russ Willard, Baker said: "The United States Supreme Court's order will allow all parties involved in this case another opportunity to be heard on the issues raised, including the question of recantations. Hopefully this hearing will resolve the doubts about the verdict handed down by the Chatham County jury 18 years ago."

A key player who has remained largely silent on the matter is Larry Chisolm, who took over as Chatham County district attorney in January after longtime DA Spencer Lawton Jr. elected to retire. In a now-familiar refrain, Chisolm said in a press release issued Monday that his office would have no public comment on the substance of the court's ruling or the facts of the case until the federal courts have concluded their hearings and appeals. He noted Baker's office would continue to represent the state in the federal hearing.

"The citizens of Chatham County should be clear in their understanding that this is not a new trial of the case before a jury," Chisolm explained in his statement. "The hearing of this case before a federal judge affords Troy Davis the opportunity to have any evidence that supports his innocence claim that was found after the trial to be heard all at one time in court. As a result, the case could continue to execution, be sent back for re-trial or appealed once again. We do not expect a quick outcome in any event."

It's unclear which district judge will handle the case. U.S. District Judge John F. Nangle, a Missouri senior federal judge who handled cases in semi-retirement at the U.S. District Court for the Southern District of Georgia, dealt with earlier proceedings in the Davis matter. Nangle died about a year ago.

As of Monday afternoon, the case had not reached the district court to be assigned to a judge, according to district court clerk Scott L. Poff.

Mike Mears, a death penalty defense expert at Atlanta's John Marshall Law School who previously signed on to an amicus brief supporting Davis at the state Supreme Court, said he didn't know what the district judge would do with the case. "Anybody who can tell you that -- they're going to be more prescient than I am about the future," he said.

He said Monday's decision raises more questions about how courts should deal with witness recantations than it answers. "I'm glad for Troy Davis," said Mears. "I just think that this is not the end of the story for future cases."

The case was In re Troy Anthony Davis, No. 08-1443.