Shamima Begum is set to begin her appeal over the removal of her UK citizenship.
Ms Begum fled her east London home for Syria as a 15-year-old schoolgirl with Kadiza Sultana and Amira Abase to join the so-called Islamic State (IS) group more than seven years ago.
She has denied any involvement in terror activities and is challenging a Government decision to remove her citizenship, while Ms Sultana was reportedly killed in a Russian air raid and Ms Abase is missing.
It has since been claimed that she was smuggled into Syria by a Canadian spy.
A Special Immigration Appeals Commission hearing is to start on Monday at Field House tribunal centre, London, and is expected to last five days.
In February 2019 Ms Begum was found, nine months pregnant, in a Syrian refugee camp. Her British citizenship was revoked on national security grounds shortly afterwards.
She challenged the Home Office's decision, but the Supreme Court ruled that she was not allowed leave to enter the UK to pursue her appeal.
Last summer, during an interview, Ms Begum said she wanted to be brought back to the UK to face charges and added in a direct appeal to the Prime Minister that she could be "an asset" in the fight against terror.
She added that she had been "groomed" to flee to Syria as a "dumb" and impressionable child.
According to the BBC and The Times, Mohammed Al Rasheed, who is alleged to have been a double agent working for the Canadians, met the girls in Turkey before taking them to Syria in February 2015.
Both news organisations reported that Rasheed was providing information to Canadian intelligence while smuggling people to IS, with The Times quoting the book The Secret History Of The Five Eyes.
Begum family lawyer Tasnime Akunjee previously said in a statement: "Shamima Begum will have a hearing in the SIAC (Special Immigration Appeals Commission) court, where one of the main arguments will be that when former home secretary Sajid Javid stripped Shamima Begum of her citizenship leaving her in Syria, he did not consider that she was a victim of trafficking.
"The UK has international obligations as to how we view a trafficked person and what culpability we prescribed to them for their actions."
