Thursday's ruling says the prisoners at Guantanamo Bay — and, for that matter, terror detainees anywhere — can be held and put on trial, just not by the military commissions the president set up on his own.
The ruling is a victory for one of the first to be arrested while combat raged in Afghanistan, Salim Hamdan, a former bodyguard for Osama bin Laden. He was sent to Guantanamo Bay four years ago and later put on trial there before a special military commission ordered by the president.
But Thursday, the Supreme Court ruled that the commission lacked the authority to try anyone.
Hamdan's military lawyer said the decision shows that the war on terrorism is no excuse for abandoning fair trials.
"It means that we can't be scared out of who we are," said Lt. Cmdr. Charles Swift. "And that's victory, folks."
The court's five-member majority — Justices John Paul Stevens, Anthony Kennedy, David Souter, Ruth Bader Ginsburg and Stephen Breyer — said the commissions failed to follow a longstanding federal law that requires all military courts to provide fair trial rights.
Lawyers for Guantanamo detainees said the military commission set up there lacked those basic protections.
"It didn't allow them, most importantly, to confront evidence against them," said detainee lawyer Thomas Wilner. "Indeed, it didn't even allow them to sit in their own trials, to see the witnesses or examine the evidence against them."
The ruling also said the Geneva Conventions apply to trials for the detainees and require regularly operating military proceedings, like a court martial, not the president's tribunal with its limited rights.
Chief Justice John Roberts, who ruled on this issue in a lower court, sat this one out.
Justices Antonin Scalia, Clarence Thomas and Samuel Alito dissented, saying the president's war-making powers allow him to tailor the military trials to a terrorist enemy.
A former Justice Department lawyer agrees.
"The court has essentially reversed the Bush administration's position that al-Qaida detainees have no rights under the Geneva Convention," says Andrew McBride.
As for Guantanamo Bay, human rights lawyers say the president now has a reason to close it down.
"This is what he's been saying," says attorney Bill Goodman. "He's looking for guidance from the Supreme Court. Well, wake up. Hello. They've given you guidance. Yes, shut it down."
Justice Clarence Thomas felt so strongly that this was the wrong ruling that for only the second time in his 15 years on the court, he read his dissent out loud.
So what happens next?
One is to just use regular court-martial trials. But the administration seems to prefer going to Congress to get authority to have tribunals with limited rights. Thursday night, congressional leaders said they'll start looking into that after the Fourth of July holiday.