Radical Islamic cleric Abu Hamza and four other terror suspects are expected to find out if they have won their latest legal move to avoid extradition from the UK to America for trial on terrorism charges.
Two judges at the High Court in London heard from Home Secretary Theresa May's QC that if they rule in her favour that "effectively is the end", as no further appeal was available in criminal cases.
Mr James Eadie agreed with Sir John Thomas, President of the Queen's Bench Division, that he will be saying to the court that "the Secretary of State would be entitled to move instantly".
Sir John said it was the "final court if we refuse permission". He indicated on Thursday, at the end of a three-day hearing, that he intends to give his ruling on Friday at a time still be to fixed.
Lawyers for 54-year-old Hamza, a former imam at Finsbury Park mosque in north London, asked Sir John and Mr Justice Ouseley to continue an injunction preventing his extradition pending medical tests recommended by two doctors.
His QC Alun Jones said an MRI (magnetic resonance imaging) brain scan could establish that he is unfit to plead because of degenerative problems and should not be extradited to face trial on terrorism charges. Mr Jones said Hamza's health is "deteriorating" and he is suffering from long-term depression, inability to concentrate and short-term memory loss.
Although the court has still to give its final ruling, Sir John suggested in the course of the argument that, if there was a risk of a degenerative condition, "the sooner he is put on trial the better - I don't conceivably see how a delay can conceivably be in the interests of justice".
Hamza is one of five terror suspects who have launched last-ditch legal challenges at the court after the European Court of Human Rights refused to stop their US extradition. The judges are also giving their decisions in applications brought by terror suspects Babar Ahmad, Syed Ahsan, Khaled Al-Fawwaz and Adel Abdul Bary.
Ahmad, a computer expert from south London, and Ahsan are accused of offences including using a website to provide support to terrorists and conspiracy to kill, kidnap, maim or injure persons or damage property in a foreign country.
Bary and Al-Fawwaz were indicted - with Osama bin Laden and 20 others - for their alleged involvement in, or support for, the bombing of US embassies in Nairobi and Dar es Salaam in 1998. Al-Fawwaz faces more than 269 counts of murder.