Julian Assange’s moment of truth has arrived – and the stakes are high

Walk past the Royal Courts of Justice in London on a week day and you will often spot small gatherings of people holding placards and handing out leaflets about a case being held inside. On Tuesday, there will be many such souls on the pavement, making no secret of their views on a case that has ramifications for journalism around the world.

Inside, in a packed court, two high court judges will hear arguments in an application for leave to appeal that Julian Assange, the founder of WikiLeaks, should not be taken from the high-security Belmarsh prison to face a trial and a potential 175-year jail sentence in the US, where he faces 18 criminal counts for his alleged role in obtaining and disclosing classified documents.

These revealed details of US activities in Iraq and Afghanistan, including attacks on civilians. They also revealed details of the US treatment of prisoners in Guantánamo Bay and links to clandestine activities in the Middle East.

Earlier this month, in an unconnected case, former CIA officer Joshua Schulte was sentenced in New York to 40 years for leaking classified information to WikiLeaks.

A key aspect of the prosecution of Assange that has emerged is the attempt by US authorities to persuade journalists who have been critical of Assange, an often controversial figure, to give evidence against him.

At least four well-known journalists have been approached by the Metropolitan police on behalf of the FBI:

James Ball, his ex-WikiLeaks colleague, who is now with the Bureau of Investigative Journalism; David Leigh, the former Guardian and Observer journalist; Heather Brooke, a freedom of information campaigner; and Andrew O’Hagan, who had been commissioned to ghost Assange’s autobiography.

All of them have declined to coo