The US is trying to extradite the Australian to face 17 charges of violating the US Espionage Act and one of conspiring to commit computer intrusion over leaking and publishing thousands of classified US diplomatic and military files in 2010.

The charges carry a potential total prison sentence of 175 years.

Barrister James Lewis, for the US government, insisted the hearing was merely a procedure to confirm there were no blocks to extradition.

"This is an extradition hearing, not a trial," he said in Woolwich Crown Court last week.

"The guilt or innocence of Mr. Assange will be determined at trial in the United States, not in this court."

Lewis accused Assange of "common criminality", alleging at least four US informants in Iraq, Iran, China and Syria couldn't be found or disappeared after WikiLeaks published unredacted diplomatic files.

Defence lawyers argued the Trump administration initially offered Assange a presidential pardon before pursuing him in a "war on leakers and journalists".

Barrister Edward Fitzgerald alleged the Americans even thought about poisoning or kidnapping the Australian.

"This is not about criminal justice. It is about the manipulation of the system to ensure the US government was able to make an example of Julian Assange," he said.

Colleague Mark Summers, QC, said Assange took "extreme measures" to heavily redact informants' names until Guardian journalist David Leigh published the password protecting the files in his book.

Summers said Assange warned the US State Department and only published after the cables appeared alongside the password on the file-sharing websites Crymptome and PirateBay.

Lewis responded that Assange's disclosures had amplified their public accessibility.

The hearing also debated the Australian's motivations, which Fitzgerald said had been purely political.

"WikiLeaks did effect change, that was one of the reasons there was (US troop) withdrawal (from Iraq), we also say that the US frequently said: 'WikiLeaks opposes US policy in Afghanistan'," he said.

''What other purpose can there be publishing the Apache helicopter strike (video) and (US) rules of engagement showing that the war conflicted with fundamental human rights?

"What other point can there be to releasing the Guantanamo Bay files than to induce a government change of policy, and the same for revealing for civilian deaths in Iraq war (it) was to induce a change in government policy.''

Lewis argued that "political offences" don't exist under English law, so the US charges are criminal offences.

But Fitzgerald said the extradition request was made under the UK-US extradition treaty, which exempts political offences.

Meanwhile, Assange has had little do with the hearing, yawning and squinting up at the skylight from the glass-enclosed dock.

After the hearing's opening day, his lawyers said, he was stripped naked twice, handcuffed 11 times and had his legal case files confiscated.

On the second day someone controversially took a photograph of him inside the court.

Assange complained of being like a spectator "watching Wimbledon" on the third day, and on the fourth his barristers applied for the "gentle man of an intellectual nature" to be able to sit with them on the bench.

But District Court Judge Vanessa Baraitser knocked them back, offering instead to adjourn the court whenever Assange needed to speak with his legal team in the privacy of the holding cells.

The full extradition hearing resumes on May 18 for at least three weeks.

Australian Associated Press