In another blow to the Bush administration, the Supreme Court ruled Thursday that foreign terrorism suspects held at Guantánamo Bay have the constitutional right to challenge their detention in U.S. civilian courts.
The 5-4 ruling was the high court's third setback for the administration since 2004 over its treatment of prisoners held indefinitely and without charges at the U.S. naval base in Cuba.
''The laws and Constitution are designed to survive, and remain in force, in extraordinary times,'' Justice Anthony Kennedy wrote for the majority.
It was not immediately clear whether this ruling, unlike the first two, would lead to prompt hearings for the detainees, some of whom have been held more than six years. Roughly 270 men remain at the island prison, classified as enemy combatants and held on suspicion of terrorism or links to al Qaeda and the Taliban.
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The Guantánamo prison has been harshly criticized at home and abroad for the detentions themselves as well as the aggressive interrogations that were conducted there.
The court said not only that the detainees have rights under the Constitution, but that the system the administration put in place to classify them as ''enemy combatants'' and review those decisions is inadequate.
The administration had argued that the detainees have no rights, and that the classification and review process was a sufficient substitute for the civilian court hearings that the detainees seek.
President Bush, in Rome for a meeting with Italian Prime Minister Silvio Berlusconi, said the U.S. government will `` abide by the court's decision. That doesn't mean I have to agree with it . . . It's a deeply divided court and I strongly agree with those who dissented. We'll study this opinion.''
In dissent, Chief Justice John Roberts criticized his colleagues for striking down what he called ``the most generous set of procedural protections ever afforded aliens detained by this country as enemy combatants.''
Justices Samuel Alito, Antonin Scalia and Clarence Thomas also dissented.
Scalia wrote that the nation is ''at war with radical Islamists'' and that the court's decision ``will make the war harder on us. It will almost certainly cause more Americans to be killed.''
Justices Stephen Breyer, Ruth Bader Ginsburg, David Souter and John Paul Stevens joined Kennedy in the majority.
In New York, a civil liberties group, which had filed hundreds of unlawful detention petitions for Guantánamo detainees, welcomed the decision.
''The Supreme Court has finally brought an end to one of our nation's most egregious injustices,'' said Vincent Warren, executive director of the Center for Constitutional Rights.
Warren called the Bush administration's decision to strip the detainees of habeas corpus rights a ''six-year-long nightmare'' and ``a lesson in how fragile our constitutional protections are in the hands of an overzealous executive.''
The Supreme Court's ruling came in the case named for Lakhdar Boumediene, a 42-year-old former relief worker who was taken captive by U.S. forces in Sarajevo in 2002. His lawyers said the man -- who has never been charged by the United States with a crime -- had worked for the Islamic counterpart of the Red Cross, the Red Crescent.
His lawyers said that U.S forces spirited Boumediene and five other men from Europe to Turkey to Guantánamo for interrogation after Bosnian police cleared them of plotting to blow up the U.S. Embassy in Sarajevo.
The Center for Constitutional Rights said that the decision did not directly apply to those captives facing charges by military commissions, the war crimes court set up by the Bush administration and approved by Congress in 2006.
Those people number 20. They included alleged 9/11 mastermind Khalid Sheik Mohammed, a Pakistani once held by the CIA and now charged with a crime punishable by death, and Osama bin Laden's driver, Salim Hamdan, a Yemeni charged with supporting al Qaeda, a crime with a maximum penalty of life in prison.
Rather, the ruling directly applied to those in a state of legal limbo, with no charges, held as ''enemy combatants'' under an indefinite detention system set up by the Pentagon in the war on terror.
For those facing a commission, ''there's actually a military commission set up, whatever we think of the process,'' said Michael Ratner, president of the Center for Constitutional Rights.
''Secondly, they have attorneys,'' Ratner said. ``Thirdly, they have the right to confront in some fashion the evidence against them.''
Other attorneys said those facing commissions might now be able to use petitions in the federal courts to challenge the commissions themselves.
The court has ruled twice previously that people held at Guantánamo without charges can go into civilian courts to ask that the government justify their continued detention. Each time, the administration and Congress, then controlled by Republicans, changed the laws to try to close the courthouse doors to the detainees.
In addition to those held without charges, the United States has said it plans to try as many as 80 of the detainees in war crimes tribunals, which have not been held since World War II.
Miami Herald staff writer Carol Rosenberg contributed to this report.