WASHINGTON, Sept. 1 — The legal battle over the rights of the hundreds of men held as enemy combatants at Guantánamo Bay has lasted more than five years, including two rounds in the Supreme Court. Now, as the parties prepare for their next Supreme Court confrontation later this fall, the arguments have come full circle to where they began: over the role of the federal courts.

The Military Commissions Act of 2006, which Congress passed in its final weeks under Republican control in order to negate the Supreme Court’s most recent ruling on behalf of a Guantánamo detainee, stripped all courts of jurisdiction “to hear or consider” challenges to any alien detainee’s continued detention. In a surprising about-face the day after it concluded its term in June, the Supreme Court accepted renewed appeals on behalf of two groups of detainees and agreed to decide whether the measure is constitutional.

Lawyers for the detainees and for dozens of organizations and individuals supporting them filed their briefs late last month. Two dozen briefs poured into the court. The government’s brief and those of any supporting groups are due by Oct. 9, with the argument likely to be scheduled soon after Thanksgiving.

The Supreme Court, of course, is only one forum among several in which the fate of the Guantánamo detainees is being debated. Democrats in Congress have tried, without success so far, to restore the federal courts’ jurisdiction to hear the detainees’ challenges to their confinement. And voices within the Bush administration have urged consideration of closing the detention camp altogether.