A U.S. military appeals court on Wednesday vacated the conviction of David Hicks, an Australian who pleaded guilty to providing material support to terrorism.
The court found that the activity for which Hicks was convicted was not an offense triable by military commission at the time he was caught.
"We are very happy for David. Today's decision is a powerful reminder that he committed no crime, he is innocent of any offense," said Wells Dixon, senior staff attorney at the Center for Constitutional Rights. "David Hicks can now be truly free of Guantanamo."
Hicks was captured by U.S. troops in 2001 in Afghanistan after the U.S.-led attacks against the Taliban were launched. He was transferred to Guantanamo in 2002 as one of its original detainees.
He was held there for five years before entering a guilty plea in 2007.
Under a pretrial agreement, Hicks was sentenced to seven years in prison. However, all but nine months of that was suspended. Because of a transfer agreement between the United States and Australia, Hicks was returned to Australia to serve that time. He was released from prison in late 2007.
"I'm looking forward to getting on with my life now that my name has been cleared," Hicks told reporters in Sydney.
He spoke about the physical ailments he suffers as a result of his time at Guantanamo, and suggested the Australian government should be responsible for his medical expenses.
"They were aware of the conditions I was being held in at the time. I think they should at least pay my medical expenses. That's not much to ask for, I think."
He said he was kept in metal rooms in freezing conditions for years, and wasn't able to move or exercise.
"The body deteriorates over five and a half years, even without the added torture, such as stress positions, being beaten, etc.," he said.
"I'm in need of operation on my left knee, my right elbow, my back. My teeth keep getting pulled because I couldn't brush them for five and a half years," he said. "It's becoming a very expensive exercise to fix myself from the years of torture."
Australian Prime Minister Tony Abbott has ruled out issuing an apology to Hicks.
"I'm not in the business of apologizing for the actions that Australian governments take to protect our country. Not now, not ever," he said, according to CNN affiliate SBS.
In a statement, Australia's Attorney-General George Brandis said the ruling was based on a question of law, not on whether Hicks had engaged in the alleged activities.
He suggested he would have been convicted under Australia's current anti-terror laws.
"Mr. Hicks has made a number of admissions regarding his activities, including in letters to his family and in his book, for example that he undertook training with militia and terrorist groups such as al-Qaeda in Afghanistan and that he had met Osama bin Laden on many occasions and considered him a 'brother.'"
Hicks' lawyer Stephen Kenny said his client had traveled to Afghanistan for military training, but that wasn't what Wednesday's ruling was about.
"What he was doing there was not at that time illegal. He wasn't doing anything that was a breach of Australian, international or U.S. law. And that's what this decision today confirms," Kenny said.
When asked by a reporter whether he was angry, Hicks said no: "I think I'm too defeated to have any anger. I'm just worn out."