In prison since 2004, Ahmad has been held without charge for the longest period of any British citizen detained since the Sept. 11 attacks.
In a statement read on his behalf outside court, Ahmad said his case had exposed flaws in U.S.-U.K. extradition arrangements. "I leave with my head held high, having won the moral victory," he said.
His father, Ashfaq Ahmad, said he would continue to fight for his son.
"It's not just one Babar Ahmad. Tomorrow there will be another Babar Ahmad and another one," he said.
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