America's highest court has delivered a catastrophic blow to George Bush's policy of locking up terror suspects without charge in Guantanamo Bay.
The US Supreme Court dismissed the legal basis upon which the Bush administration has interned nearly 300 inmates at the American naval base in Cuba and granted the prisoners the right to challenge their detention on the US mainland.
Lawyers for the inmates, including the British resident Binyam Mohamed, are now expected to file fresh claims for release in the US federal courts.
Britain is among a growing number of US allies who supported George Bush's war on terror after the attacks on America in 2001 but now want to see the prison camp closed. Gordon Brown is expected to discuss the subject during the President's state visit to Britain next week.
Yesterday's majority 5-4 ruling was the Bush administration's third setback since 2004 at the highest US court over its treatment of prisoners who are being held indefinitely and without charge or fair trial.
The court has ruled twice previously that Guantanamo inmates could go into civilian courts to challenge their continued detention. But each time, the Bush administration and Congress, then controlled by Republicans, changed the law to keep the detainees out of civilian courts.
Brushing aside arguments that the suspects were enemy combatants held at a time of war, the court said yesterday that the detainees had, "the constitutional privilege of habeas corpus", the right of detainees under the US constitution to have their cases heard by an independent judge or be freed. Justice Anthony Kennedy said: "The laws and constitution are designed to survive, and remain in force, in extraordinary times."
Judges, law clerks and court administrators were desperate to read Judge Kennedy's 70-page opinion yesterday as they work out how to proceed. Chief Judge Royce C Lamberth will call a special meeting of federal judges to address how to handle the cases.
Clive Stafford Smith, director of the human rights group Reprieve, said he would be looking at the judgment to see whether he could use it to seek the suspension of the military prosecution of Binyam Mohamed, a 29-year-old Londoner who has been held by the Americans for six years.
Last week, five detainees, including Khalid Sheikh Mohammed, allegedly "the principal architect of the 9/11 attacks", appeared before a military tribunal in Guantanamo Bay.
Reprieve said the logical conclusion of the Supreme Court ruling would be the release of all the inmates and the closure of Guantanamo Bay. Zachary Katznelson, the group's legal director, described the judgment as, a great victory: "After this ruling, Guantanamo Bay prisoners have the right to say: you made a mistake with me – set me free."
Mr Stafford Smith said the decision did not resolve everything in favour of the prisoners. "This is a catastrophic blow for George Bush's secret prisons policy," he said. "The Bush administration has had three strikes in the US courts – and they're out. But the prisoners still have a long way to go."
"Gordon Brown must recognise that this does not move Binyam Mohamed any closer to freedom. It will be a long while yet before the promise of this decision becomes a reality.
"The simple fact is that Binyam and the rest of the 270 prisoners will continue to languish in prison unless their governments stand up for them."
Amnesty International also called on Mr Brown to use his influence with Mr Bush to close the camp. In particular, the Prime Minister is being asked to press for guarantees of a safe trial – "in an ordinary civilian court" – or safe releases for three Guantanamo prisoners who are either formerly resident in the UK or have with links to the UK.