Washington ? The Supreme Court reversed itself Friday and agreed to consider whether detainees at Guantanamo Bay have been unfairly barred from the federal courts by the Bush administration and Congress, a move that may finally determine legal rights for foreign-born terrorism suspects.

The case, which could become one of the most important of the court’s next term, will address whether subjecting the detainees to military commissions instead of allowing them access to federal courts violates the Constitution. In April, the court had decided not to hear an appeal from the detainees.

Friday’s decision to change course and hear the case was so unusual that lawyers and court experts went to the archives to try to find the last time it had happened. The only consensus was that it had been decades.

“The Supreme Court is going to decide the simple question: Does the Constitution protect the detainees?” said Georgetown University law professor Neal Katyal, who successfully argued the detainee case the court decided just a year ago. In that case, the justices said President Bush did not have authority to set up the military tribunals the administration thought should hear the cases against the detainees.

In April, three justices – David Souter, Ruth Bader Ginsburg and Stephen Breyer – said they were eager to hear the appeals, which presented questions that “deserve this court’s immediate attention.” But it takes four justices to agree to take a case.

Justices John Paul Stevens and Anthony Kennedy said at the time they would continue to monitor the legal proceedings involving the detainees. It takes five votes to re-hear a denial, so perhaps the two justices concluded they’ve seen enough. The court’s order is silent on which justices agreed to hear the case.

David Remes, a lawyer for some of the detainees who brought the case, said the court didn’t have to make the decision to take the case now, “so what obviously happened is the justices decided to confront the issue sooner rather than later.”

Department of Justice spokesman Erik Ablin said, “We are disappointed with the decision, but are confident in our legal arguments and look forward to presenting them before the Court.”

The court’s action comes as both Congress and the White House are looking for ways to close the military prison at Guantanamo Bay, Cuba, and transfer approximately 370 prisoners.