A British court could give a final decision on Monday on whether WikiLeaks' founder Julian Assange should be extradited to the United States over the mass leak of secret U.S. documents, the culmination of 13 years of legal battles and detentions.

Two judges at the High Court in London are set to rule on whether the court is satisfied by U.S. assurances that Assange, 52, would not face the death penalty and could rely on the First Amendment right to free speech if he faced a U.S. trial for spying.

Assange's legal team say he could be on a plane across the Atlantic within 24 hours of the decision, could be released from jail, or his case could yet again be bogged down in months of legal battles.

"I have the sense that anything could happen at this stage," his wife Stella said last week. "Julian could be extradited, or he could be freed."

She said her husband hoped to be in court for the crucial hearing.

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

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

The U.S. authorities want to put the Australian-born Assange on trial over 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 ranged from human rights groups and some media bodies, to Australian Prime Minister Anthony Albanese and other political leaders.

DETAINED SINCE 2010

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 held since 2019 in Belmarsh top security jail, latterly while he waited a ruling on his extradition.

"Every day since the seventh of December 2010 he has been in one form of detention or another," said Stella Assange, who was originally part of his legal team and married him in Belmarsh in 2022.

If the High Court rules the extradition can go ahead, Assange's legal avenues in Britain are exhausted, and his lawyers will immediately turn to the European Court of Human Rights to seek an emergency injunction blocking deportation pending a full hearing by that court into his case at a later date.

On the other hand, if the judges reject the U.S. submissions, then he will have permission to appeal his extradition case on three grounds, and that might not be heard until next year.

It is also possible the judges could decide that Monday's hearing should consider not just whether he can appeal but also the substance of that appeal. If they find in his favour in those circumstances, he could be released.

Stella Assange said that whatever the outcome she would continue to fight for his liberty. If he is freed she plans to follow him to Australia or wherever he was safe. If he is extradited, she said all the psychiatric evidence presented at court had concluded he was at very serious risk of suicide.

"We live from day to day, from week to week, from decision to decision. This is a way that we've been living for years and years," she told Reuters.

"This is just not a way to live - it's so cruel. And I can't prepare for his extradition - how could I? But if he's extradited, then I'll do whatever I can, and our family is going to fight for him until he's free."

(Reporting by Michael Holden Editing by Kate Holton and Frances Kerry)