Protesters gathered outside the U.S. Supreme Court building in Washington as Bush administration lawyers faced off inside against lawyers representing 305 detainees at Guantanamo Bay, Cuba.
The two sides are arguing over the indefinite detention of foreign terrorism suspects, including Canadian Omar Khadr, who are being held as "enemy combatants."
"Restore habeas corpus!" the group of about two dozen protesters, some clad in orange prison jumpsuits, chanted on Wednesday.
"We believe these people should be charged or allowed to go home," said Liz Hourican of the peace group Code Pink.
Khadr, 21, has been imprisoned in Cuba since he was 15. Khadr is suspected of lobbing the grenade that killed U.S. Army Sgt. Christopher Speer in a 2002 firefight in Afghanistan.
Khadr's trial last month, which pondered the question of whether he is an "alien, unlawful, enemy combatant," has been rescheduled for dates in December and January.
Wednesday's Supreme Court hearing involves arguments on whether the detainees can challenge their detention in an impartial U.S. civilian court -- a right enshrined in the U.S. Constitution.
In two other cases, the justices have ruled against the Bush administration.
In 2006, the White House and Congress changed the law that allowed detainees the right to argue their cases in U.S. courts. The most recent legislation, last year's Military Commissions Act, strips federal courts of their ability to hear detainee cases.
The Bush administration contends the detention of suspects is humane, lawful and necessary to fight the threat of global terrorism.
Solicitor General Paul Clement, representing the administration, said foreigners captured and held outside the United States "have no constitutional rights to petition our courts for a writ of habeas corpus," a judicial determination of the legality of detention.
Seth Waxman, who is representing the detainees contends, "After six years of imprisonment without meaningful review, it is time for a court to decide the legality of" their confinement.
The case could come down to whether the Guantanamo Bay facility is considered to be on U.S. soil, which would make the constitutional claim by detainees stronger.
The Guantanamo prison was established in 2002 after the U.S.-led invasion of Afghanistan.
Many of the detainees have been imprisoned for up to six years without charge and have complained of abuse and mistreatment.
It's unlikely that many of the detainees held will see a trial as the U.S. has no plans to formally charge the suspects. Only three detainees currently face charges under the Military Commissions Act, but the military has said it could prosecute as many as 80.
With files from The Associated Press
