Shamima Begum, the London schoolgirl who travelled to Syria to join ISIS, has begun a legal challenge against the stripping of her British citizenship.
Ms Begum, 20, was found in a refugee camp in the war-torn country in February by a British reporter. She left the UK in 2015.
Representing her in court, Tom Hickman QC said his client was in "an incredibly fragile and dangerous" position in a refugee camp.
After Ms Begum gave interviews, the then home secretary Sajid Javid revoked her citizenship.
A preliminary hearing taking place this week will decide whether Ms Begum should be allowed to return to the UK from Syria to give evidence.
The Special Immigration Appeals Commission is hearing the challenge and will deal with the question of whether depriving her of British citizenship rendered her stateless and was therefore unlawful.
Mr Javid revoked her citizenship amid claims that she had Bangladeshi citizenship. Ms Begum’s parents are from Bangladesh.
But the Bangladeshi Foreign Minister, Shahriar Alam, said Ms Begum did not have Bangladeshi citizenship.
The UK government said she was a citizen by descent under Bangladeshi law and therefore is not stateless.
But Ms Begum's lawyers said if she went to Bangladesh she could face the death penalty.
"The Bangladeshi government has made clear it will not allow the appellant to go to that country. It has said that if she arrived covertly she would be hanged," they said in legal papers.
Tasnime Akunjee, who is representing the London-born ISIS member, said earlier on Tuesday that she would argue that she was a victim of rape by her husband.
"She was married in an Isis ceremony within two weeks of reaching Syria to a 23-year-old fighter," Mr Akunjee told the Daily Mirror. "Her context is as a rape victim, or a statutory rape victim."
Ms Begum said she was married at the age of 15 to Dutch ISIS fighter Yago Riedijk, who is being held in a Kurdish detention centre. They had three children, all of whom have died.
Ms Begum's first interview when she was discovered by a journalist working with The Times caused outrage in the UK, because she appeared to be unrepentant about having joined the terrorist group.
"When I saw my first severed head in a bin it didn't faze me at all," she told the paper.
"It was from a captured fighter seized on the battlefield, an enemy of Islam. I thought only of what he would have done to a Muslim woman if he had the chance."
Ms Begum's lawyers said in submissions to the court that she had only expressed sympathetic views towards ISIS to protect herself and her newborn son Jarrah while staying in Al Hol refugee camp.