Abu Qatada is to be freed after winning his latest appeal against extradition, in a major blow to Home Secretary Theresa May.
The Special Immigration Appeals Commission (Siac) decided the radical cleric would not get a fair trial in Jordan because evidence obtained via torture could be used against him.
This is despite the Home Secretary securing assurances from the country that this would not happen.
Qatada will be released on bail after Home Office lawyers failed to persuade Siac judges he should remain behind bars.
They insisted that the Palestinian-born Jordanian cleric, real name Omar Mahmoud Mohammed Othman, poses "an enormous risk to national security".
But Edward Fitzgerald QC, for Qatada, declared: "Enough is enough. It has gone on for many years now. There is no prospect of deportation taking place within a reasonable time, in fact there is no prospect at present of deportation at all."
The successful appeal is the latest twist in a battle that has lasted more than a decade.
Siac has already rejected the Government's application to challenge the decision but permission can still be sought at the Court of Appeal. Home Secretary Theresa May announced to MPs in the House of Commons that she will contest the ruling.
"Last year the Jordanian constitution was amended to make clear that not only is torture forbidden, but that any statement extracted from a person under duress or the threat thereof, shall neither be taken into consideration nor relied on," she said.
"Despite these assurances to allow Qatada a fair trial and despite the change to the Jordanian constitution, in the absence of clear case law, Mr Justice Mitting still found in Qatada's favour. In doing so, we believe he applied the wrong legal test."
Shadow Home Secretary Yvette Cooper agreed that, while "every avenue should be pursued" to secure Qatada's deportation, Ms May was to blame for errors which led to the Siac ruling.
"There has been a catalogue of confusion and mistakes over Abu Qatada from this Home Secretary, including getting basic dates wrong earlier this year," she said.
"The Home Secretary needs to say urgently what she is now doing to get Abu Qatada's deportation back on track and to keep the public safe in the meantime. We cannot have any more mistakes that simply leave the public at risk."
Speaking outside Siac, Qatada's solicitor Gareth Peirce said: "It is important to reaffirm this country's position that we abhor the use of torture and a case that was predicated upon evidence from witnesses who have been tortured is rejected - rejected by the courts of this country as by the European Court.
"We clearly agree with the decision, of course we do, but it is important to emphasise the fundamental rules of law that we subscribe to. To that extent, it is important for other cases, not just for this case."
Asked about the inevitable reaction of the British public to Qatada's release, she said: "We understand that this is a difficult case that has been challenging for everyone, of course we understand that.
"But I think the time has come in the world, with the conflicts in the world, for us to talk to each other and understand each other and enter into dialogue, and perhaps nothing is as black and white as it is painted."
The Home Office said the Government "strongly disagreed" with the ruling.
"We have obtained assurances not just in relation to the treatment of Qatada himself, but about the quality of the legal processes that would be followed throughout his trial," a spokesman said.
"Indeed, today's ruling found that 'the Jordanian judiciary, like their executive counterparts, are determined to ensure that the appellant will receive, and be seen to receive, a fair retrial'. We will therefore seek leave to appeal."
Qatada, once described by a judge as Osama bin Laden's right-hand man in Europe, was allowed to stay in Britain in 1994 but was convicted of terror charges in Jordan in his absence in 1999.
The cleric, who is said to have wide and high-level support among extremists, featured in hate sermons found on videos in the flat of one of the September 11 bombers.
In December 2001, he became one of Britain's most wanted men after going on the run from his home in west London. He was arrested almost a year later and detained in Belmarsh prison.
He has been in and out of jail in the intervening years and was rearrested in April amid hopes in Government that he could finally be removed from the country.
His legal team lodged a fresh appeal at the European Court of Human Rights but lost, and took the fight back to the British courts and Siac.
At the hearing last month, Jordan expert Professor Beverley Milton-Edwards warned that a fair trial for Qatada there was "unlikely".