By Jon Silverman
Legal affairs analyst
As expected - and as fervently hoped by civil liberties lawyers - the US Supreme Court has ruled that Guantanamo Bay is not a legal black hole.
About 600 suspects are being held at Guantanamo Bay
The Bush administration has argued consistently that inmates held there have no right to challenge the conditions of their detention because the US courts do not have jurisdiction over the base.
That position has now been declared untenable by the nine Supreme Court judges, paving the way for a clutch of habeas corpus applications by detainees.
Steven Watt, a lawyer with the New York-based Centre for Constitutional Rights, described it as "a crucially important ruling, showing that the US courts can offer protection against torture or summary execution".
In London, the director of Fair Trials Abroad, Stephen Jakobi, said: "It's a triumph because it means eventual freedom for the detainees, even if it is still a long way off, and the reassertion of Western values guaranteeing fair trials."
Mr Jakobi speculated that the ruling would allow the UK government to go to court in the US to try to secure the release of the four British citizens still held at Guantanamo - though all the signs are that Prime Minister Tony Blair hopes to achieve that through diplomacy rather than the law.
It should not be forgotten that the Supreme Court has also ruled that the policy of detaining both US nationals and foreign citizens as "enemy combatants" without either charge or trial in a domestic court is lawful.
This validates the "war on terror" wherever the US seeks to prosecute, whether at home or through proxies in countries such as Jordan, Syria and Egypt, where al-Qaeda suspects are being held, often in brutal conditions.
It also chimes with actions taken by other governments, such as Britain's - which is holding more than a dozen foreign-born men in Belmarsh prison without trial.
The Supreme Court's judgments may have implications for the military tribunals being planned to try some of those held at Guantanamo.
So far, only a handful of people have been charged, but two of the four Britons have been named as potential defendants.
It seems unlikely that the hearings will proceed until the Supreme Court has dealt with the habeas corpus challenges - and that might not be for another year or so.
In a fortnight, lawyers will meet in New York to consider the implications of the rulings and plot their next moves.
They will have plenty to chew over.