In a Federal Court judgment published on Monday, Justice Anthony Besanko launched a scathing criticism against the former SAS corporal who had "motives to lie" about the events in Afghanistan.
"I find that (Mr Roberts-Smith) was not an honest and reliable witness," the judge wrote.
During a 2009 raid on Easter Sunday on a compound codenamed Whiskey 108 in Uruzgan Province, Mr Roberts-Smith machine-gunned an unarmed prisoner in the back, taking the man's prosthetic leg back to Australia to use as a beer drinking vessel.
Mr Roberts-Smith also stood silent while a rookie soldier was ordered to execute an elderly Afghan prisoner so he could be "blooded".
Justice Besanko called the former SAS corporal's denials of these incidents "highly improbable" after hearing from independent witnesses with no reason to be dishonest.
The same could not be said about Mr Roberts-Smith, the judge said.
"The applicant has motives to lie, being a financial motive to support his claim for damages in these proceedings, a motive to restore his reputation which he contends has been destroyed by the publication of the articles and significantly, a motive to resist findings against him which may affect whether further action is taken against him."
Justice Besanko found one of the newspapers' central claims - that Mr Roberts-Smith had kicked an unarmed and handcuffed man, Ali Jan, off a 10-metre cliff and then ensured he was shot - was true.
As evidence of his guilt, Mr Roberts-Smith attempted to cover up the unlawful killing at Darwan in September, 2012 by removing Mr Jan's handcuffs and planting a radio alongside his lifeless body before he was photographed.
Mr Roberts-Smith then told fellow SAS soldiers who witnessed the incident to stick to an approved story that Mr Jan was a spotter who they killed legitimately.
In accepting the newspapers' claims, Justice Besanko also rejected Mr Roberts-Smith's account of the incident, which was riddled with a "number of improbabilities".
In October, 2012 in the Chinartu district, Mr Roberts-Smith also ordered another soldier to execute an unarmed Afghan prisoner being interrogated after his troop discovered a fake wall cavity filled with weapons, including rocket propelled grenades and warheads.
"Person 12 then gave instructions to an NDS-Wakunish soldier who then shot the Afghan male in circumstances amounting to murder. The applicant was complicit in and responsible for murder," said Justice Besanko.
In his summary judgment delivered on Thursday, Justice Besanko dismissed the cases against The Age, The Sydney Morning Herald, The Canberra Times and three journalists over their reports published in 2018.
Lifeline 13 11 14
Open Arms 1800 011 046
