The Court of Appeal decided that the case raised a point of law of public importance that only the Supreme Court can resolve.
Earlier this month, three Court of Appeal judges ruled Ms Begum should be allowed back to London to fight for the return of her citizenship. The government said that decision was deeply flawed.
Ms Begum, now 20, was one of three schoolgirls who left London to join the Islamic State group in Syria in 2015. After she was found in a refugee camp in 2019, her British citizenship was revoked by former Home Secretary Sajid Javid on security grounds.
Separately, the court has revealed that the Sun newspaper will be referred to the Attorney General after it obtained a copy of the Court of Appeal’s draft judgement – or its “essential contents” – in advance of it being handed down on 16 July.
It had been given to the parties involved on 9 July.
Lady Justice King, the head of the panel of three judges, said they were referring the newspaper to the Attorney General because of a potential contempt of court in publishing a story about the judgement – seemingly leaked from government – before it was announced in court.
The judge also granted Ms Begum’s lawyers permission to challenge a decision that the absence of a fair and effective appeal over the citizenship decision did not necessarily mean it should be restored – subject to the Supreme Court accepting that part of the case.
Sir James Eadie, representing the Home Office, said earlier there was a “big issue at stake” in the case, to decide what should happen when someone cannot have a fair appeal over being stripped of their citizenship as a “result of going abroad and aligning with terrorist groups”. He said it was “an issue of real pressing public importance” which was “perhaps the central democratic issue of our times”.