The court is undertaking a fresh review of the Bush administration's aggressive use of preventive detention for terror suspects. The administration asserts that the president has the authority to order the military to detain anyone suspected of being an al Qaeda member.
The administration's policy is being challenged by Ali al-Marri, a Qatar native who is the only alleged enemy combatant seized and held on U.S. soil. The government says al-Marri is an al Qaeda sleeper agent.
Al-Marri, represented by the American Civil Liberties Union, says he cannot be imprisoned without charge or trial. He was arrested in Peoria, Illinois, and has been held in virtual isolation in a U.S. Navy brig near Charleston, South Carolina, for almost 5½ years.
The 4th U.S. Circuit Court of Appeals in Richmond, Virginia said in a split decision that the president has such power, but al-Marri must be given a chance to convince a federal judge that he is not an enemy combatant.
The administration argued that al-Marri's case should first go to federal district court in South Carolina, instead of to the Supreme Court.
Al-Marri said that the case was of such constitutional importance that it should be heard by the high court now, and the justices apparently agreed.
The case will not be argued before March, meaning that Barack Obama will be the U.S. president, and decisions about al-Marri will be made by him.
During the presidential campaign, Obama repeatedly criticized President George W. Bush for being too aggressive in asserting executive authority.
Brooke Anderson, chief national security spokeswoman for the transition, has previously refused to say what Obama would do about al-Marri. She did not immediately comment Friday.
It is rare for an incoming administration to reverse course on a case before the high court, although it has happened.
The new administration has options if it wishes to avert a Supreme Court hearing.
It could send al-Marri home to Qatar, or transfer him back to civilian court to face criminal charges.
The government followed the latter path in the case of U.S. citizen Jose Padilla rather than have the high court take up the matter. Padilla, who was held in the same brig as al-Marri, was convicted in a criminal trial in federal court in Miami.
Documents and information on al-Marri's case can be viewed on the Web site of the Brennan Center for Justice at New York University School of Law.
By Associated Press Writer Mark Sherman