When he entered the embassy in Knightsbridge, central London, Assange was wanted by Swedish authorities in connection with sexual assault allegations. But he feared any arrest would eventually lead to extradition to the US, and prosecution for the activities of his brainchild, WikiLeaks. WikiLeaks had published classified US military logs supplied by Chelsea Manning, who was charged under the Espionage Act.

Though Stockholm has since abandoned the sex crime charges against Assange, a British arrest warrant remains in place due to his failure to answer bail in 2012. In court, Assange’s legal team relied on a technical point, claiming the warrant has “lost its purpose and function” if the underlying criminal proceedings against their client have ceased. They said it made little sense for officers to continue monitoring the embassy when the 46-year-old is no longer wanted by Sweden.

Their hopes were dashed last week when senior district judge Emma Arbuthnot said she was not convinced by their argument.In response, Assange’s lawyer, Mark Summers QC, told the judge the case should nevertheless be discontinued because it was not proportionate in the interests of justice.

His argument relied on four points: that Assange had reasonable grounds for the course that he took; that the UN has ruled he’s been arbitrarily detained; that he offered his cooperation to the Swedish investigators at all times; and that his years of embassy exile could be considered an adequate punishment for his actions.

What enticed the judge most was emails obtained under the Freedom of Information Act revealing the UK Crown Prosecution Service advised the Swedes against interviewing Assange in London in 2010 or 2011, a dialogue that could have prevented the long-running political impasse.

Furthermore the CPS, which has admitted destroying key emails relating to the case, told Sweden not to drop its extradition request when the country moved to do so in 2013, a time when the Metropolitan police had revealed that its security operation to prevent Assange escaping the embassy had already cost £3.8m.

“Obviously these emails are of interest to the court,” Arbuthnot said.

Assange, who has been involved in the publication of a series of controversial leaks that include the Iraq war logs, US state department cables and Democratic party emails, says recent developments in the US prove his concerns were well founded.

Former FBI director James Comey told Congress last year the only reason Assange had not been apprehended was because he was in the embassy. The US attorney general, Jeff Sessions, called his arrest a “priority”, and the CIA director, Mike Pompeo, said Assange had no first amendment rights and the CIA was working to “take down” WikiLeaks.

Should the judge rule in Assange’s favour on Tuesday, it remains unlikely that he will leave the embassy immediately. But a court victory might force British authorities to disclose any outstanding US extradition warrants.

“The CPS emails prove what we have been saying for years: this case could have and should have been resolved years ago,” Assange’s lawyer Jennifer Robinson told the Guardian on Tuesday. “The US government has made clear its intention to bring a prosecution against WikiLeaks. The UK FCO refuses to confirm or deny whether there is an extradition request for Mr. Assange. In our recent FOI challenge against the CPS […] the CPS refused to disclose certain material because it would ‘tip off’ Mr Assange about a possible US extradition request.

“It is time to acknowledge what the real issue is and has always been in this case: the risk of extradition to the US.”

Robinson said Assange’s case was a test for the freedom of the press to publish. “I have worked on various aspects of his case since 2010 – from offering to give his testimony to Sweden before the arrest warrant was issued, to walking him into the police station in London after the warrant was issued unnecessarily, to attending the US v Manning proceedings and hearing US evidence about WikiLeaks, to his claim for asylum, to our UN appeal – and since.

“His case is unprecedented. I have been dismayed by the repeated refusal of various state authorities – in Sweden, in the UK, in Australia – to use available procedures to resolve his case in a just, fair and proportionate manner.”

Other lawyers who have followed the case said quashing the warrant had its pitfalls. Edward Grange, a partner at law firm Corker Binning, said the fact remained that Assange had chosen to enter the embassy to avoid arrest. “It would be a dangerous precedent to set if the warrant could just be withdrawn on public interest grounds, because that would be seen as a reward for individuals who decide to avoid administrative justice,” Grange said.

Assange continues to maintain that WikiLeaks’ mission is akin to that of the New York Times or Washington Post – to publish newsworthy content. To fans, he is the man in the high castle, a reclusive paragon of free speech who turned whistle-blowing into a mass movement. “I have given up years of my own liberty […] to bring truth to the public,” he wrote last year.

But his detractors, including many on the liberal left, accuse him of collaborating with Russian propagandists in undermining Hillary Clinton’s bid for the presidency, and of supporting a populist style of politics favoured by Donald Trump or Vladimir Putin. Assange has been outspoken in his support of Brexit and Catalan independence. While he can list celebrities such as PJ Harvey, Brian Eno and Noam Chomsky as friends, he is judged for visits from the likes of Nigel Farage.

The Australian national was made an Ecuadorian citizen last month, but the UK refused to give him diplomatic status, which would have conferred legal immunity.

His doctors and lawyers say his physical and mental health has suffered; he has a fractured tooth, a shoulder injury that requires an MRI scan, and depression.

Seemingly unmoved, Arbuthnot implied last week that Assange was a man who wields power and influence online. “It could be argued he’s managed to live [his life] via his computer,” the judge said.

Summers replied: “Being able to use a computer is no substitute for liberty.”