A British appeals court ruled on Thursday that 20-year-old Shamima Begum can return to contest a government decision to strip her of her citizenship after she left for Syria in 2015 to join Islamic State. “Fairness and justice must, on the facts of this case, outweigh the national security concerns,” Judge Julian Flaux wrote on the court’s behalf, although he added that if authorities considered her a security risk, she should be arrested and maintained in detention upon her return. Begum, who had dual British-Bangladeshi citizenship, married a member of ISIS and bore at least three children, although they died in a Syrian detention camp. On having her presence in the camp become known last year, she asked to be repatriated. She achieved a certain amount of notoriety in Britain when it became known that she had run away with two school friends to join ISIS in Syria via Turkey, and again when she justified a 2017 suicide bombing in the city of Manchester that killed 22 people. The Interior Ministry says it will appeal the court’s ruling.