Julian Assange, an activist and whistleblower, and the U.S. government have been pitted against each other for more than a decade.
The Australian-born Assange can appeal to the British Supreme Court, a process that could take weeks or months. He remains in prison after being denied bail.
The ruling is the latest stage in an international game of cat and mouse that began nearly a decade ago. Assange spent seven years in the Ecuadoran Embassy in London, claiming political asylum to avoid arrest after jumping bail when Sweden requested his extradition over sexual assault allegations.
The Swedish charges were dropped in 2017, but after the embassy evicted Assange last year, he was arrested by the British police on behalf of the United States. His extradition trial was delayed by the coronavirus pandemic.
Assange’s fate is of political importance in the United States, where WikiLeaks, which published hacked Democratic National Committee data, has been accused of playing a significant role in the 2016 election.
Advocates of free expression have argued that an Assange trial in the United States would be a setback for press freedom.