The home secretary's Abu Qatada appeal against the decision to allow radical preacher Abu Qatada to stay in the UK is due to be heard on 25 February.
Theresa May will raise her challenge before Three Court of Appeal judges.
The legal move follows a ruling by the Special Immigration Appeals Commission (Siac) that Qatada should not be deported to Jordan, where he was convicted of terror charges in his absence in 1999.
Qatada was first detained by authorities in 2002
A panel of three judges found there was a risk that evidence obtained using torture would be used against the controversial cleric in a retrial.
The Siac judges ruled on 12 November 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.
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."
May immediately pledged to appeal and told the Commons that Jordan had given assurances about its legal processes.
She described Qatada as "a dangerous man, a suspected terrorist, who is accused of serious crime in his home country of Jordan".
Qatada was granted bail following the ruling and released from HMP Long Lartin, returning to his family home in London.
He has fought deportation for more than a decade and has so far thwarted every attempt by the Government to deport him.
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