Shamima Begum, who left the UK for Syria to join the Islamic State group as a teenager, will not be allowed to return and fight her citizenship case, the Supreme Court has ruled.
The court said in a unanimous ruling that her rights were not breached when she was refused permission to return.
Ms Begum, 21, wants to come back to challenge the home secretary’s decision to remove her British nationality.
She is in a camp controlled by armed guards in northern Syria.
Ms Begum was 15 when she and two other east London schoolgirls left the UK and travelled to Syria to join the Islamic State group in February 2015.
Two years ago, the then-Home Secretary Sajid Javid stripped Ms Begum of her citizenship on national security grounds.
Last July, the Court of Appeal ruled that the only fair way forward was to allow her into the UK because she could not effectively appeal against the decision from the camp in northern Syria.
The Home Office subsequently appealed to the Supreme Court to reconsider the Court of Appeal’s judgement, arguing that allowing her to return to the UK “would create significant national security risks”.
On Friday, Lord Reed, president of the Supreme Court, said the government had been entitled to prevent Ms Begum from returning to the UK.
Announcing the ruling, Lord Reed said: “The Supreme Court unanimously allows all of the home secretary’s appeals and dismisses Ms Begum’s cross-appeal.”
He said the Court of Appeal’s judgment had been wrong and failed to take proper account of the home secretary’s case.
“It did not give the home secretary’s assessment the respect which it should have received, given that it is the home secretary who has been charged by Parliament with responsibility for making such assessments, and who is democratically accountable to Parliament for the discharge of that responsibility,” Lord Reed said.
“The Court of Appeal mistakenly believed that, when an individual’s right to have a fair hearing… came into conflict with the requirements of national security, her right to a fair hearing must prevail.”
He added: “But the right to a fair hearing does not trump all other considerations, such as the safety of the public.”
Lord Reed said the appropriate answer was not to force the government to bring Ms Begum back to the UK – but to pause her legal fight over citizenship until she is in a safer position to take part in her appeal.
He added: “That is not a perfect solution, as it is not known how long it may be before that is possible. But there is no perfect solution to a dilemma of the present kind.”