Shamima Begum is set to discover whether she has won a Court of Appeal challenge over the removal of her British citizenship.
Ms Begum travelled to Syria in 2015 aged 15 and her citizenship was revoked on national security grounds shortly after she was found in a Syrian refugee camp in February 2019.
Last year, the now 24-year-old lost a challenge against the decision at the Special Immigration Appeals Commission (SIAC).
Ms Begum’s lawyers brought a bid to overturn that decision at the Court of Appeal, with the Home Office opposing the challenge.
Three appeal judges are due to give their ruling on Ms Begum’s appeal on Friday.
At a hearing in October, Samantha Knights KC told the court the Government had failed to consider the legal duties owed to Ms Begum as a potential victim of trafficking or as a result of “state failures” in her case.
She said in written submissions: “The appellant’s trafficking was a mandatory, relevant consideration in determining whether it was conducive to the public good and proportionate to deprive her of citizenship, but it was not considered by the Home Office.
“As a consequence, the deprivation decision was unlawful.”
However, Sir James Eadie KC, for the department, said decisions over whether someone is a victim of trafficking or whether they should be deprived of their citizenship “have fundamentally different bases and roles”.
He continued: “The focus in the trafficking regime is on the protection of the individual and there’s really no countervailing public interest at that point.
“But here the regime is different, the regime in operation is the deprivation regime and the rationale is entirely different, it is the protection of the public at large.”
The barrister later said the “key feature” of Ms Begum’s case was national security.
Sir James continued in written submissions: “The fact that someone is radicalised, and may have been manipulated, is not inconsistent with the assessment that they pose a national security risk.
“Ms Begum contends that national security should not be a ‘trump’ card. But the public should not be exposed to risks to national security because events and circumstances have conspired to give rise to that risk.”
During the appeal bid, Ms Begum’s lawyers said the UK failed to have a “full and effective” investigation into how she was allegedly trafficked.
In its ruling last year, the SIAC concluded there were “arguable breaches of duty” by state bodies – including the Metropolitan Police, Tower Hamlets Council and Ms Begum’s school – in not preventing her from travelling to Syria.
Ms Knights told the Court of Appeal at the start of the three-day hearing these “failures” could have also been unlawful and contributed to Ms Begum’s trafficking.
However, Sir James said the SIAC was right to find there was “no direct connection between any potential failures, by other public authorities, in 2015” and ministers’ decision to deprive Ms Begum of her citizenship.
The ruling from the Lady Chief Justice Baroness Carr, Lord Justice Bean and Lady Justice Whipple is due to be handed down at a short hearing at 10am on Friday.