The UK government was right to strip a terrorism suspect of his citizenship and ban him from the country, according to a ruling from the European Court of Human Rights (ECHR).
The Sudanese-born man, who for legal reasons can only be referred to as "K2", is suspected to have taken part in terrorism-related activities in Somalia in 2009.
An earlier court hearing in the UK heard that K2, along with two associates, "engaged in a variety of terrorism-related activities linked to al-Shabaab activities, including terrorism-related training and fighting against AMISOM [peacekeeping] forces," according to a security service assessment.
He applied to the ECHR after then home secretary Theresa May used executive powers to bar him. He argued that the ban violated his right to respect for his private and family life, as enshrined in article 8 of the European Convention on Human Rights.
The ECHR has been criticised by some politicians and commentators for making it harder for the UK to deport and ban terrorists. But the court's order said May had "acted swiftly and in accordance with the law", and that the complainant's arguments were inadmissible and "without merit".
The ECHR ruling comes after the UK Court of Appeal and Supreme Court all upheld the government's order.
The ruling adds that K2 left the UK willingly while on bail for a public order offence and that he would not be left stateless because of his Sudanese citizenship.
The case caused some controversy after he was granted legal aid worth hundreds of thousands of pounds to fight the UK's order at the ECHR.
Theresa May has argued that the UK should leave the European Convention on Human Rights – which was incorporated into British law as the Humans Rights Act – because it "makes us less secure by preventing the deportation of dangerous foreign nationals".
But plans to replace it with a British "bill of rights" as outlined in the 2015 Conservative manifesto were put on hold due to a lack of support in parliament.
A Home Office spokesperson said: "This government puts the safety of our families, communities and country first and we welcome the court’s judgment.
"Citizenship is a privilege not a right and it is right that the home secretary can deprive an individual of their citizenship where it is believed it is conducive to the public good to do so."