WikiLeaks founder Julian Assange is at "high risk of suicide" if extradited to the US to face claims he endangered the lives of whistleblowers around the world, a court has heard.
Opening the case against the 48-year-old on Monday, James Lewis QC said some sources "disappeared" after he put them at risk of "serious harm, torture or even death".
He told District Judge Vanessa Baraitser that information published by WikiLeaks was "useful to an enemy" of the US – with material found at al Qaida leader Osama bin Laden's compound in Pakistan when he was killed in a 2011 raid.
But lawyers for Assange claim he is the victim of a politically-motivated prosecution stemming from US President Donald Trump's "war on investigative journalists" and could face "fatal consequences" if he is extradited.
Assange is wanted in the US to face 18 charges, including espionage and hacking allegations, over "one of the largest compromises of classified information" in the country's history.
He could face up to 175 years in jail if found guilty of all of the charges, which relate to 2010 and 2011.
Mr Lewis told Woolwich Crown Court, which is sitting as a magistrates' court, that most of the charges relate to "straightforward criminal activity".
He said Assange was involved in what was described as a "conspiracy to steal from and hack into" the department of defence computer system, along with former US army intelligence analyst Chelsea Manning.
"These are ordinary criminal charges and any person, journalist or source who hacks or attempts to gain unauthorised access to a secure system, or aids and abets others to do so, is guilty of computer misuse," Mr Lewis said.
"Reporting or journalism is not an excuse for criminal activities or a licence to break ordinary criminal laws.
"This is true in the UK as it is in the USA, and indeed in any civilised country in the world."
He said three charges relate to the dissemination of specific documents which put sources at risk.
"By disseminating the materials in an unredacted form, he likely put people – human rights activists, journalists, advocates, religious leaders, dissidents and their families – at risk of serious harm, torture or even death," he said.
He said that the US identified hundreds of "at-risk and potentially at-risk people" around the world and made efforts to warn them.
"The US is aware of sources, whose redacted names and other identifying information was contained in classified documents published by WikiLeaks, who subsequently disappeared, although the US can't prove at this point that their disappearance was the result of being outed by WikiLeaks," he added.
"What Mr Assange seeks to defend by free speech is not the publication of the classified materials, but he seeks to defend the publication of sources – the names of people who put themselves at risk to assist the US and its allies," Mr Lewis continued.
"He is not charged with the disclosure of embarrassing or awkward information that the government would rather not be disclosed. The disclosure charges are solely where there was a risk of harm."
Representing Assange, Edward Fitzgerald QC said the extradition would be the "height of inhumanity", exposing him to a lengthy sentence in an American prison and leading to a "high risk of suicide".
He said it was "completely misleading" to suggest Assange and WikiLeaks were to blame for the disclosure of unredacted names and that the extradition should be barred because it was politically motivated.
"President Trump came into power with a new approach for freedom of the press... amounting effectively to declaring war on investigative journalists," he said.
"It's against that background the Trump administration decided to make an example of Julian Assange, he was the obvious sign of everything Trump condemned."
And he made allegations that spies had considered kidnapping or poisoning Assange while he was holed up inside the Ecuadorian embassy in London.
The claim was made by a whistleblower who also said private security agents from Spanish firm UC Global, acting on behalf of the US, were involved in "intrusive and sophisticated" surveillance.
The extradition hearing will be adjourned at the end of this week of legal argument, and continue with three weeks of evidence scheduled to begin on May 18.
The decision, which is expected months later, is likely to be appealed against by the losing side, whatever the outcome.
Scores of protesters, some of whom had pitched tents nearby, made so much noise that they could be heard inside the packed courtroom with a full public gallery, including Assange's father, John Shipton.
The noise, which included a siren, chanting and singing, was so loud it prompted a clean-shaven Assange, wearing a grey suit and grey sweater over a white shirt, to address the court before the lunch break.
He said: "I'm having difficulty concentrating. All this noise is not helpful either.
"I understand and am very grateful of the public support and understand they must be disgusted..."
But the judge stopped him from speaking, instead asking his lawyer to address her.
Assange has been held on remand in Belmarsh prison since last September after serving a 50-week jail sentence for breaching his bail conditions while he was in the Ecuadorian embassy in London.
He entered the building in 2012 to avoid extradition to Sweden over sex offence allegations, which he has always denied and which were subsequently dropped.