Once described by a Spanish judge as "Osama bin Laden's right-hand man in Europe", Abu Qatada has used human rights laws to fight deportation for more than a decade.
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 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.
He was granted bail following the ruling by three SIAC judges and released from HMP Long Lartin, returning to his family home in London.
However, on Monday the Government will challenge the decision in front of three Court of Appeal judges led by Lord Dyson, the Master of the Rolls.