LONDON — A British judge is due to deliver a decision Monday on whether WikiLeaks founder Julian Assange should be extradited to the United States to face charges of violating the Espionage Act, in a case that could have profound implications for press freedoms.

Assange is charged with 18 federal crimes, including conspiring to obtain and disclose hundreds of thousands of pages of secret government documents, including classified diplomatic cables and sensitive military reports from the wars in Iraq and Afghanistan, which were released through the WikiLeaks website and also directly to journalists.

Prosecutors want Assange flown by U.S. marshals to Northern Virginia to face the charges, which expose him to a possible 175-year sentence in a maximum-security prison.

In a series of hearings over the past year, Assange’s lawyers have argued before British Magistrate Vanessa Baraitser that the Trump administration is targeting the 49-year-old Australian for “purely political” reasons.

The Assange legal team and its witnesses contend that his prosecution upends protections for journalists and publishers and that he would be denied a fair trial in a U.S. court, in part because he is a foreigner and an outspoken anti-authority figure.

To counter the extradition request, Assange’s British lawyers also presented witnesses to testify that their client suffers from Asperger’s syndrome, that his mental health is “fragile” and that he is at “high risk of suicide.”

Michael Kopelman, professor of neuropsychiatry at King’s College London, told the court in September that Assange suffers from anxiety, depression and auditory hallucinations, that he has planned and imagined taking his own life, and that faced with imminent extradition, “he would indeed find a way to commit suicide.”

Since a gray-bearded Assange was expelled from the Ecuadoran Embassy in London in April 2019 and dragged away by British police, the anti-secrecy crusader has languished behind the gray walls of Belmarsh prison outside the capital. He has been denied bail while waiting for the extradition request to be settled.

British legal experts say the British judge could, for example, accept the premise that the prosecution is political in nature but still find that Assange could get a fair trial at the U.S. District Court in Alexandria, Va.

“There really is no precedent for a British court to find that the American criminal justice system is incapable of giving him a fair trial,” said Nick Vamos, formerly head of the extradition unit at the Crown Prosecution Service and now a partner at Peters & Peters law firm in London.

Vamos said British courts have blocked extradition to countries with disreputable courts, such as Russia, and others with inhumane and degrading prisons. “But there’s much respect for the U.S. system,” he said.

If Assange’s extradition is blocked, it would probably be because the judge agrees that Assange’s mental health poses too great a risk. Even here, the bar is set very high, as the U.S. prisons are filled with mentally ill inmates, and James Lewis, the lawyer representing the U.S. government, argued in court that they receive adequate care.

Yet there is recent precedent for denying a U.S. request on the grounds pursued by Assange.

On appeal, the British High Court in 2018 blocked the extradition of the activist Lauri Love, who was charged in 2013 with hacking into U.S. government computers to steal confidential data. Love’s lawyers presented evidence that he suffered from depression and would try to take his life if extradited. U.S. prosecutors later dropped the charges.

The losing side will almost certainly appeal to the High Court to reverse the lower court’s decision. That process — and a possible further appeal to Britain’s Supreme Court — could take six more months.

In recent weeks, Assange supporters have urged President Trump to issue a pardon for the WikiLeaks activist.

In the Daily Mail tabloid, Stella Morris, Assange’s partner and the mother of their two children, published an open appeal to Trump on Sunday.

She wrote that she had nightmares about Assange “being buried in the deepest, darkest corner of the [U.S.] prison system for the rest of his life” because he “embarrassed Washington and this is their revenge.”

But, she added, “the nightmares came to a sudden stop the week before Christmas, when a groundswell of support from all sides of the political spectrum called for President Trump to pardon him.”

Morris, who is Assange’s former attorney, wrote that “leading figures, from former vice-presidential candidate Sarah Palin to Nobel Prize winners, such as human-rights campaigner Adolfo Perez Esquivel, have been calling for Julian’s freedom.”

To prove that the prosecution’s case is tainted by politics, one of Assange’s lawyers, Jennifer Robinson, testified that she was present at an Aug. 16, 2017, meeting at the Ecuadoran Embassy in London where former congressman Dana Rohrabacher (R-Calif.), an ally of Trump, offered Assange a pardon from the president in exchange for saying that Russia had nothing to do with the 2016 hack and leak of emails from the Democratic National Committee.

In a statement posted on his website last year, Rohrabacher denied the details but not the meeting.

The former congressman said he was on his “own fact finding mission at personal expense” and that “at no time did I offer Julian Assange anything from the President because I had not spoken with the President about this issue at all.”

During the extradition hearings last year, Daniel Ellsberg, the former RAND Corporation analyst who leaked the Pentagon Papers in 1971, testified that the Assange prosecution would undermine traditional protections for investigative journalists and the whistleblowers they rely upon.

Ellsberg told The Washington Post on Sunday that he thinks there is “a small chance, but not zero” that Trump will either pardon Assange or order the case to be dropped.

“Why? To stick it to the intelligence community, Trump’s ‘deep state,’ ” Ellsberg said.

The Assange affair is much different from past espionage cases. No prior case has so squarely tested the limits of the First Amendment.

In court filings and news conferences, U.S. prosecutors have sought to distinguish Assange and WikiLeaks from the mainstream press, arguing that no reporter would help a source try to break into encrypted files or expect legal protection if they did.

“Julian Assange is no journalist,” Assistant Attorney General for National Security John Demers said when the charges were announced. “This is made plain by the totality of his conduct as alleged in the indictment.”

In addition to his alleged violations of the Espionage Act and the publishing of classified documents, U.S. prosecutors have charged Assange with conspiracy to commit “computer intrusions” by helping Army intelligence analyst Chelsea Manning try to hack a password.

In a superseding indictment unsealed in June, prosecutors say he also solicited hackers to break into Icelandic government computers to steal information.

The U.S. Court of Appeals for the 4th Circuit, which reviews cases from federal court in Alexandria, ruled in a 2013 leak case that a reporter had no First Amendment protection from testifying before a grand jury.

But no case law explains the difference between a responsible or irresponsible publisher of classified information, and press organizations have warned that Assange’s prosecution sets a dangerous precedent by leaving the Department of Justice as arbiter of that line.

Barry Pollack, one of Assange’s American attorneys, said the evidence used to make Assange appear reckless is weaker than it seems. “The actual facts that came out at the extradition hearing are wildly different than what was portrayed in the indictment,” he said.

As part of the extradition case, prosecutors indicated that they have considered the First Amendment implications of the case and possible responses, including that Assange, as an Australian citizen, is not covered by U.S. free speech protections.

Mark Zaid, a national security lawyer who regularly represents whistleblowers, argued that Assange is so far outside the world of journalism in his motives and behavior that his case has no implications for the mainstream press.

“They are anarchists whose intent is to undermine the United States and other democracies,” he said of Assange and his followers.

He noted that the Pentagon Papers decision left the door open to prosecution of reporters. Assange supporters say the charges against the WikiLeaks founder create a “slippery slope” that could lead to more prosecutions of journalists. Zaid said that possibility already exists.

“It has been well-known for decades that the U.S. government could prosecute journalists and publishers for possessing and publishing classified information, and it has always chosen not to,” he said.

Weiner reported from Washington.