The Home Secretary has been given a Friday 13th deadline to seek assurances from the US authorities over how a UK terror suspect will be treated if he is extradited to America for trial.
Two High Court judges warned Theresa May that if there are no US assurances by 4pm on June 13, her decision to go ahead with the extradition of Haroon Aswat, despite a European court ruling blocking his removal, will be quashed.
Aswat is facing 11 terrorist charges and is accused by the US of conspiring with Abu Hamza, whose trial is due to begin this week, to establish a jihad training camp in Oregon.
His extradition was blocked last year by judges in the European Court of Human Rights, who ruled that he could face inhumane treatment as there were no guarantees over where he would be detained.
His lawyers argued at a hearing at London's High Court earlier this month that he was mentally ill but could face potential confinement in ADX Florence, a "supermax" US jail.
Aswat, a British citizen, was transferred from prison to Broadmoor psychiatric hospital in 2008 suffering with paranoid schizophrenia.
Once suspected of having links to the 7/7 bombers but never charged, Aswat has so far avoided extradition because of his mental illness.
The 39-year-old who was born in Batley, West Yorkshire, is accused of conspiring with Hamza to establish the training camp in Oregon between June 2000 and December 2001. He denies any terrorism involvement.
Hamza was extradited to America in 2012 with four other terrorism suspects after legal battles against extradition.
A decision on Aswat was adjourned and the Strasbourg human rights court ruled last year that, because of his severe mental illness, his case was not the same as Hamza's and that he should not be extradited.
The European judges found extradition would be a violation of Article 3 of the European Convention on Human Rights, which protects against inhuman and degrading treatment.
They expressed particular concern that it was uncertain in what prison or detention facility, such as ADX Florence, Aswat would be held in America, before or after trial.
The European judges said there was "a real risk that the applicant's extradition to a different country and to a different and potentially more hostile prison environment would result in a significant deterioration in his mental and physical health, and that such a detention would be capable of reaching the Article 3 threshold".
The Home Secretary announced in September 2013 her decision not to withdraw her extradition order, despite the European Court ruling.
Her decision was challenged at London's High Court by lawyers acting for Aswat in a hearing on April 1 and 2 before the Lord Chief Justice, Lord Thomas, and Mr Justice Mitting.
James Eadie QC, appearing for the Home Secretary, said fresh information from the US Department of Justice meant that it was "extremely unlikely" that Aswat would ever be held at ADX Florence.
He argued that in any event he would receive the necessary medical care, wherever he was held, to safeguard his mental health.
But Edward Fitzgerald QC, for Aswat, said the risk remained that he could suffer inhuman and degrading treatment in breach of his human rights.
Mr Fitzgerald argued the new information from the US did not alter the position and the Home Secretary could not rely on it to absolve herself of the European court's "binding decision" that extradition should not take place.
He said that would "undermine the rule of law".
Adjourning the case Lord Thomas said there had been a failure by the Home Secretary to give "the kind of assurances envisaged in the judgment of the Strasbourg court".
He and Mr Justice Mitting unanimously ruled a final decision in the case should be postponed for 60 days for the US government to consider whether it wished to give the kind of assurances demanded by Strasbourg - or extradition would be blocked.
Both judges agreed that the basic concerns of the Strasbourg court could only be met if the Americans agreed to transfer Aswat to a psychiatric referral centre and kept him there until his treating clinician "determines that he could be transferred to another institution without compromising his health and safety". Otherwise he would have to be kept at the centre until trial.
The judges agreed extradition would have to be preceded by detailed discussions between Aswat's UK clinician and the US psychiatrist who would take charge of him in America.
Mr Justice Mitting said: "By those means, the real risk of relapse into an acute psychotic state which formed the basis of the Strasbourg court's decision would be removed."
Lord Thomas said: "It is entirely a matter for the Government of the United States whether they wish to give any such assurances, but it seems to us that it is only with the provision of such assurances that, in the light of the judgment of the Strasbourg court in this particular case, extradition of the claimant would be compatible with Article 3."
The judge said the English court was "constrained by the approach and findings" of the European judges and stressed: "I have come to the conclusion we have reached only because of the approach taken by the Strasbourg court."
Lord Thomas expressed concern over the degree of intervention and "fact- finding" conducted by the European judges in the Aswat case.
He said the case involved "an intensive and difficult fact-finding exercise" and suggested that in future "such fact-finding exercises are best undertaken by a national court".
He said: "A national court is much better equipped to hear the evidence and clarify difficulties through a trial process conducted by a national judge, with questioning of the relevant witnesses in that process, if necessary."
It was agreed that Aswat had a serious mental illness and his case was "but one example of the procedural processes which a national court can deploy to ascertain the facts".
The judge added: "This case illustrates, therefore, a real and substantial difficulty that can arise when such a fact-finding exercise is undertaken by the Strasbourg court in place of the national court."