The government is reviewing legal aid eligibility rules following the decision to allow Shamima Begum to return to the UK to face trial, Boris Johnson has said.
Earlier this week the Court of Appeal ruled that Begum, who travelled to Syria to join ISIS in 2015, should be allowed to fight the decision to strip her of her citizenship in person in a British court.
The court decided that the 20-year-old, who is currently in refugee Camp Roj in northern Syria, could only mount a "fair and effective appeal" if she was in the UK.
But the prime minister called the decision “odd and peverse” on Sunday, adding that the government would be reviewing the legal aid rules.
"It seems to me to be at least odd and perverse that somebody can be entitled to legal aid when they are not only outside the country, but have had their citizenship deprived for the protection of national security,” Johnson told The Sunday Telegraph.
"That, amongst other things, we will be looking at."
The prime minister said that the government would also be looking at the whole system of judicial review to establish whether it had "perverse consequences".
"What we are looking at is whether there are some ways in which judicial review does indeed go too far or does indeed have perverse consequences that were not perhaps envisaged when the tradition of judicial review began," he said.
Begum travelled to Syria and lived under IS rule for more than three years before she was found, nine months pregnant, in a Syrian refugee camp in February last year.
Then-home secretary Sajid Javid revoked her British citizenship on national security grounds later that month.
Begum took legal action against the Home Office, claiming the decision was unlawful because it rendered her stateless and exposed her to a real risk of death or inhuman and degrading treatment.
The Home Office spokeswoman said it would be applying for permission to appeal against the court's judgment.
The Court of Appeal’s ruling means the government must now find a way to allow Bergum to appear in court in London despite repeatedly saying it would not assist removing her from Syria.
Lord Justice Flaux – sitting with Lady Justice King and Lord Justice Singh – said: "Fairness and justice must, on the facts of this case, outweigh the national security concerns, so that the leave to enter appeals should be allowed."
The judge also said that the national security concerns about her "could be addressed and managed if she returns to the United Kingdom".
Daniel Furner, Begum's solicitor, said: "Ms Begum has never had a fair opportunity to give her side of the story.
"She is not afraid of facing British justice, she welcomes it. But the stripping of her citizenship without a chance to clear her name is not justice, it is the opposite."