Home Secretary Theresa May's appeal against the decision to allow Abu Qatada to stay in the UK has begun three days after the radical preacher was arrested for breaching bail conditions.
The Special Immigration Appeals Commission (Siac) decided last November that Qatada could not lawfully be deported to Jordan, where he was convicted of terror charges in his absence in 1999.
Siac judges ruled there was a danger evidence from Qatada's former co-defendants Abu Hawsher and Al-Hamasher, said to have been obtained by torture, could be used against him in a retrial in Jordan.
On Monday James Eadie QC, appearing for Mrs May, told three appeal judges the decision could not stand because Siac had taken an "erroneous" view of the position in Jordan and the legal tests that had to be applied when it came to assessing "real risk".
Mr Eadie said the evidence was that "Jordan law prohibits clearly and expressly the use of torture and the reliance on any statement obtained under duress, including torture".
Lawyers for Qatada, referred to in court papers by the name of Omar Othman, say the appeal should be refused and it is the Home Secretary's legal analysis of the Siac decision that is erroneous.
The case, expected to last one day, is being heard by Lord Dyson, the Master of the Rolls, and two other judges. It takes place three days after Qatada was arrested for breaching bail conditions.
They said: "The Secretary of State has not satisfied us that, on a retrial, there is no real risk that the impugned statements of Abu Hawsher and Al-Hamasher would be admitted probatively against the appellant."
Torture in Jordan is practised "with impunity" and there is no guarantee Abu Qatada will get a fair trial, a senior researcher at Human Rights Watch told the Huffington Post UK in October.
Despite evidence that changes to the Jordanian constitution, which have made gathering evidence by torture illegal, are not being enforced, May immediately pledged to appeal and told the Commons that Jordan had given assurances about its legal processes.
Mrs May has described Qatada as "a dangerous man, a suspected terrorist, who is accused of serious crime in his home country of Jordan".
Mr Eadie began his submissions by saying that, last Thursday, Qatada's home was searched and "a number of mobile phones and electronic media items" were found.
Qatada's bail was revoked after it was concluded that he might have been in breach of Siac bail conditions, which include a 22-hour home curfew and restrictions on his ability to communicate with others.
Mr Justice Irwin ordered on Saturday that Qatada should remain in custody after hearing "strong prima facie evidence" that mobile telephones or communications equipment had been switched on in his London house.
Mr Eadie said there would be a reconsideration of his detention on Thursday next week.
Lord Dyson, sitting with Lord Justice Elias and Lord Justice Richards, said the arrest was "irrelevant" to the appeal hearing.
Mr Justice Irwin ordered on Saturday that he should remain in custody after hearing "strong prima facie evidence" that mobile telephones or communications equipment had been switched on in his house.
Qatada, now in his early 50s, was born in Bethlehem in the West Bank at a time when it was occupied by Jordan.
He was granted bail following the ruling by three Siac judges - including chairman Mr Justice Mitting - and released from HMP Long Lartin, returning to his family home in London.
However, on Friday he was returned to Belmarsh prison where he is due to remain in custody ahead of a further bail hearing on March 21.
Qatada's wife and five children recently won an injunction preventing protesters from demonstrating outside their house.
He has used human rights laws to fight deportation for several years, running up a legal bill unofficially estimated at over £500,000.
Mrs May's lawyers will attempt to convince Lord Dyson, sitting with Lord Justice Elias and Lord Justice Richards, that the latest Siac decision is legally flawed and Qatada can at last be safely sent to Jordan
Mr Eadie said the Jordanian courts could be trusted.
"There is no real risk of a flagrant denial of justice. The Jordanian courts will consider all the evidence," Mr Eadie told appeal judges.
"They will do so in the light of the fact that there is likely to be a live issue as to whether or not statements were obtained by torture."
He said there was a prohibition in Jordan against evidence obtained by torture and added: "There is no reason to suppose that the Jordanian courts would approach these issues in a flagrantly unfair way. There is no reason to suppose they would not consider all the evidence before them."