Lawyers for Home Secretary Theresa May have asked the Court of Appeal to overturn what they condemn as a legally flawed decision to allow radical preacher Abu Qatada to stay in the UK.
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 "real risk" that 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 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.
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. 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.
Reserving judgment, Lord Dyson said the court would take time to consider its decision.