Britain should block the extradition of Julian Assange to the United States on grounds that the prosecution is politically motivated and the charges against him amount to political offenses — two factors that by treaty would bar his handover, Assange’s legal team said Monday in a London court.

Assange, who co-founded the anti-secrecy site WikiLeaks, was charged in May with violating the Espionage Act for his role in soliciting and publishing hundreds of thousands of secret military documents and diplomatic cables in 2010.

The disclosures at the time roiled the Obama administration, which feared upsetting relations with foreign allies and endangering sources in battle zones. Then-Secretary of State Hillary Clinton accused WikiLeaks of carrying out an “attack” on the international community.

Assange, 48, has also drawn controversy for his role in publishing material hacked from the Democratic Party by the Russian government during the 2016 U.S. presidential campaign. He has not been charged with crimes related to that incident. Instead he faces 17 counts of violating the Espionage Act and one for conspiracy to hack a military computer.

The use of the Espionage Act is also controversial because it is seen as opening a door to the potential prosecution of journalists for publishing classified government secrets — and a worrisome assault on press freedom.

Assange, cleanshaven and wearing a blue suit, raised a fist to acknowledge supporters in Westminster Magistrates Court. Asked by the judge if he understood the court proceedings, he mumbled, “Not really.”

He said he was fighting a “superpower” with “unlimited resources,” referring to the U.S. government. “They have unfair advantages dealing with documents. They [know] the interior of my life with my psychologist. . . . This is not equitable what is happening here.”

Assange said that he lived in fear for his life in Belmarsh Prison in southeast London and that he had no access to a computer or the Internet. “I can’t think properly,” he told the court.

His attorney Mark Summers argued that the charges against Assange, for which his extradition is sought, are on their face “political offenses.” Extradition would thus be unlawful under a 2003 treaty between the two countries, he said.

Summers also accused the U.S. government of spying on Assange and said there was a link between the “reinvigoration of the investigation” and the presidency of Donald Trump. “This is part of an avowed war on whistleblowers to include investigative journalists and publishers,” he said. “The American state has been actively engaged in intruding on privileged discussions between Mr. Assange and his lawyer.”

Summers cited a criminal case in Spain in which the CIA is accused of gaining access through a Spanish security firm to Assange’s communications as he talked to his legal team within the Ecuadoran Embassy, according to news reports. The CIA declined to comment on an ongoing case. Assange had lived in the embassy in London from 2012 until earlier this year when the Ecuadoran government withdrew its grant of asylum and expelled him. He was promptly arrested by British police.

The Justice Department declined to comment.

The political-offense argument has long been expected, with analysts saying that it offers Assange his best legal argument against extradition. Publishing official secrets “has always been treated as a political offense” in Britain, said Clive Walker, a professor emeritus of law at the University of Leeds in England. If he were the magistrate, he said, he would be thinking about equivalent legal grounds barring prosecution “on account of political opinions or in breach of human rights.”

But other analysts cautioned that the case may not be so easy to make. One British case states that to be considered a political offense “the crime must be specifically and immediately directed at ‘overthrowing or changing the government of a State or inducing it to change its policy,’” said Ashley Deeks, a professor at the University of Virginia School of Law. “Assange’s lawyers will clearly argue that that’s what Assange was trying to do — change U.S. government policy.”

But, she said, “Assange doesn’t fit the traditional mode of being a political opponent of the state trying to extradite him in that he didn’t commit the alleged act in the context of some kind of internal uprising or rebellion. That fact may give the U.K. courts some pause.”

The issue under British domestic law, legal experts said, is not whether the offense is a political one, but whether the prosecution is politically motivated. The U.S. government will argue that it is not.

“Assange’s argument would be the United States is trying to make an example out of him because of the black eye he’s given the United States on the international scene” — essentially trying to punish him for a political statement, said Stephen Vladeck, a law professor at the University of Texas at Austin.

But “political statements are not the same thing as political offenses,” he said. “This is as much about politics at the end of the day as it is about law.”

Judge Vanessa Baraitser denied Summers’s request for an extra month to gather evidence and set the first full extradition hearing for February.

Booth reported from London.