WASHINGTON (CNN) -- The Supreme Court refused Monday to jump back into an ongoing legal fight over how dozens of foreign terror suspects detained by the U.S. military at Guantanamo Bay, Cuba, will face justice before upcoming tribunals, the latest showdown over the president's war power authority.

The justices, by a 6-3 vote, denied appeals from two groups of prisoners. Preliminary hearings before military commissions in Guantanamo have already begun.

In a brief order written by Justices John Paul Stevens and Anthony Kennedy, the court noted the detainees had not gone through the usual legal routes for relief before appealing to the high court.

"Despite the obvious importance of the issues raised in these cases, we are persuaded that traditional rules governing our decision of constitutional issues ... and our practice of requiring the exhaustion of available remedies as a precondition to accepting jurisdiction."

At issue are the rights of the detainees to contest their imprisonment and the rules set up to try them as war criminals. A law passed last fall would limit court jurisdiction to hear such challenges. It is something the justices have decided twice before, ruling each time against the government's authority to hold people identified as enemy combatants.