A woman stripped of British citizenship after joining ISIS in Syria has lost her legal battle to have that decision reversed. <a href="https://www.thenationalnews.com/world/uk-news/2022/11/23/shamima-begums-school-and-police-missed-opportunities-court-told/" target="_blank">Shamima Begum</a>, 23, was 15 in 2015 when she left her home in east London with two school friends to travel to Syria. There, she married an ISIS fighter and had three children, none of whom survived. Sajid Javid, who was home secretary at the time, <a href="https://www.thenationalnews.com/world/uk-news/2022/11/21/shamima-begums-lawyers-to-plead-for-return-of-her-uk-citizenship/" target="_blank">revoked her British citizenship </a>on national security grounds after she was found in a Syrian refugee camp in February 2019, a move that left her stateless. The UK Supreme Court last year refused her permission to enter the UK to fight her citizenship case against the Home Office, so she took her case to the Special Immigration Appeals Commission (Siac). In his judgment, released on Wednesday, Mr Justice Jay said that the tribunal found there was a “credible suspicion” Ms Begum had been trafficked to Syria for sexual exploitation, “to which, as a child, she could not give a valid consent”. “In the commission’s opinion, there is a credible suspicion that Ms Begum was recruited, transferred and then harboured for the purpose of sexual exploitation,” he said. However, the specialist tribunal ruled that a finding that Ms Begum had been trafficked did not prevent the home secretary at the time from removing her citizenship. Mr Justice Jay said that the existence of this suspicion was insufficient for her to succeed in her arguments that the deprivation of her British citizenship failed to respect her human rights, adding that given she was now in Syria, the Home Secretary was not compelled to facilitate her return nor stopped from using “deprivation powers”. “This Secretary of State maintains that national security is a weighty factor and that it would take a very strong countervailing case to outweigh it," he said in a 76-page public judgment. “Reasonable people will profoundly disagree with the Secretary of State, but that raises wider societal and political questions, which it is not the role of this commission to address.” During the hearing, Ms Begum’s lawyers previously argued that her school and the police both “missed opportunities” to prevent her travelling to Syria. “The police, the school, the local authority, the Home Office and the Security Services have been blamed in various ways," Mr Justice Jay said. “In our view, putting the matter at its very lowest, there is an arguable case of failing to take reasonable preventative measures directed against the police, the school and the local authority. “The case against the Home Office is less clear cut; the case against the Security Services appears thin.” Her lawyers said the ruling has left “no protection for a British child trafficked out of the UK” and have pledged to challenge the decision. “We, the lawyers entrusted with the representation of Ms Begum in circumstances of extreme difficulty, register our profound disagreement with the decision taken by the home secretary in 2019 and the diminution by the Supreme Court of the ability of the Special Immigration Appeals Commission to consider her legal challenges," Gareth Pierce and Daniel Furner, from Birnberg Pierce Solicitors, said in a statement. “The outcome is that there is now no protection for a British child trafficked out of the UK if the home secretary invokes national security. “Regrettably, this is a lost opportunity to put into reverse a profound mistake and a continuing injustice. “Ms Begum remains in unlawful, arbitrary and indefinite detention without trial in a Syrian camp. Every possible avenue to challenge this decision will be urgently pursued. “In our view, that demands the Secretary of State must carefully review the original decision in light of the commission’s troubling findings.” Ms Begum is one of hundreds of Europeans whose fate since the 2019 collapse of the Islamist extremists' self-styled caliphate has become a thorny issue for governments. An estimated 900 people are thought to have travelled from Britain to Syria and Iraq to join ISIS. Of those, about 150 are believed to have been stripped of citizenship. Wednesday’s decision was welcomed by the Home Office. "We are pleased that the court has found in favour of the government’s position in this case," it said. “The government’s priority remains maintaining the safety and security of the UK and we will robustly defend any decision made in doing so.” Ms Begum's lawyers could now seek leave to apply to appeal against the Siac decision at London's High Court.