WikiLeaks founder Julian Assange was given permission on Monday to appeal against extradition to the United States after arguing at London’s High Court that he might not be able to rely on his right to free speech in a US court.

The Australian-born Assange, 52, is wanted in the US on 18 charges, nearly all under the Espionage Act, relating to WikiLeaks’ mass release of secret US documents — the largest security breaches of their kind in US military history.

The high court had in March granted him provisional permission to appeal on grounds that he might be discriminated against as a foreign national, but invited the US to submit assurances. After Monday’s hearing, two senior judges said Assange’s argument that he might not be able to rely on the US.

First Amendment right to free speech deserved a full appeal — which is unlikely to be held for months. The news prompted cheering and singing from hundreds of supporters who had massed outside the court tying yellow ribbons to the iron railings, holding placards and chanting “Free, free Julian Assange!”.

“As a family we’re relieved but how long can this go on?” said Assange’s wife Stella, who had been in court with his brother and father.

“The United States should read the situation and drop this case now. Now is the moment to do it.”

She told his supporters the ruling marked a turning point.

Assange himself was not present, which his lawyer said was for health reasons. The US Justice Department declined to comment on a pending judicial matter.

Had Monday’s ruling gone against him, Assange’s team said he could have been on a plane to the US within 24 hours, ending more than 13 years of legal battles in Britain.

US assurance fails to convince UK judges

US prosecutors had told the court Assange could “seek to rely” upon the First Amendment protections granted to US citizens, and would not be discriminated against because of his nationality.

But his legal team said a US court would not be bound by this. “We say this is a blatantly inadequate assurance,” Assange’s lawyer Edward Fitzgerald told the judges.

The court also concluded that Assange’s appeal should apply to all 18 counts, not only three, as lawyers for the US had argued. Fitzgerald did, however, accept a separate US assurance that Assange would not face the death penalty.

The US said its First Amendment assurances were sufficient.

James Lewis, representing the US authorities, said in court documents that the assurance “cannot bind the courts”, but that the US courts would “take solemn notice and give effect so far as they are able to a promise given by the executive”.

Protester appeal to Biden

Protesters gathered outside the court early on Monday, tying yellow ribbons to the iron railings, holding placards and chanting “Free, free Julian Assange”. In a plea to US President Joe Biden, flags read: “Let him go Joe”.

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One protester, Emilia Butlin, 54, told Reuters that she wanted to show solidarity: “He, with his work, has offered tremendous service to the public, informing them about what governments are doing in their name.”

Assange’s wife Stella appeared in court with his brother and father, but Assange stayed away for health reasons, Fitzgerald said.

WikiLeaks released hundreds of thousands of classified US military documents on Washington’s wars in Afghanistan and Iraq — the largest security breaches of their kind in US military history — along with swathes of diplomatic cables.

In April 2010, it published a classified video showing a 2007 US helicopter attack that killed a dozen people in the Iraqi capital, Baghdad, including two Reuters news staff.

The US authorities want to put the Australian-born Assange on trial on 18 charges, nearly all under the Espionage Act, saying his actions with WikiLeaks were reckless, damaged national security and endangered the lives of agents.

His many global supporters call the prosecution a travesty, an assault on journalism and free speech, and revenge for causing embarrassment. Calls for the case to be dropped have come from human rights groups, media bodies and Australian Prime Minister Anthony Albanese, along with other political leaders.

Assange was first arrested in Britain in 2010 on a Swedish warrant over sex crime allegations that were later dropped.

Since then, he has been variously under house arrest, holed up in Ecuador’s embassy in London for seven years and, since 2019, held in the Belmarsh top security jail.

He married Stella there in 2022 and the couple have two young children.