Canadian Omar Khadr is accused of killing a US soldier in 2002
Canada's government acted illegally by turning over information about a terrorism suspect to the United States, Canada's Supreme Court has ruled.
It said that handing over documents from an interview with Omar Khadr at the Guantanamo Bay prison camp violated Canada's human rights obligations.
Mr Khadr - a Canadian citizen - is the only Westerner still held at the jail.
The 21-year-old is accused of killing a US soldier and wounding another during a battle in Afghanistan in 2002.
Building a defence
Mr Khadr was 15 when he was captured during the firefight at a suspected al-Qaeda camp in Afghanistan. Canadian intelligence officials interviewed him a year later at Guantanamo Bay.
In a written statement, the Canadian court said: "By making the product of its interviews of Mr Khadr available to US authorities, Canada participated in a process that was contrary to Canada's international human rights obligations."
In an unanimous decision, the court also ruled that Mr Khadr was entitled to see at least some of the documents related to the interviews given to the US authorities.
Lawyers for Mr Khadr say they need the papers in order to help defend him against charges of murder, conspiracy and supporting terrorism before a US tribunal, which is expected to begin later this year.
Omar Khadr faces a maximum sentence of life in prison if convicted.