Two women who were born in the UK, known only as C3 and C4, had their British citizenship removed in November 2019 on the grounds of national security.
C7, a man born in Bangladesh who became a British citizen at birth, also had his British citizenship revoked in March 2020 on the basis that he had “aligned” with IS and was a threat to UK national security.
All three appealed against the removal of their British citizenship at the Special Immigration Appeals Commission (SIAC) – a specialist tribunal which hears challenges to decisions to remove someone’s British citizenship on national security grounds – in November.
The Home Office argued that all three were dual British-Bangladeshi nationals at the time their British citizenship was removed, and so the decision did not render them stateless.
But their lawyers said all three lost their Bangladeshi citizenship when they turned 21, meaning the decision did leave them stateless and was therefore unlawful.
In a ruling on Thursday, Mr Justice Chamberlain said: “C3, C4 and C7 have persuaded us that, on the dates when the decisions and the orders in their cases were made, they were not nationals of Bangladesh or any other state apart from the UK.
“This means that orders depriving them of their British citizenship would make them stateless.”
The judge added: “The Secretary of State had no power to make orders with that effect.
“For that reason – and that reason alone – the appeals against the decisions to make those orders succeed.”
A Home Office spokesman said after the ruling: “We are extremely disappointed with this judgment and the court’s decision that deprivation cannot stand in these cases.
“The Government’s priority remains maintaining the safety and security of the UK.”
Maya Foa, director of human rights group Reprieve, said: “This ruling confirms that in the Home Secretary’s rush to abdicate responsibility for these women she broke domestic and international law by rendering them stateless.
“Reprieve has established that many people from Britain currently detained in north-east Syria fit the definition of trafficked persons.
“The Government was wrong to remove citizenship from these women.
“Now that it has been restored, the Government should repatriate them so that the British justice system can address the full complexity of their cases, including the real possibility they are victims of trafficking.”