Allegations war hero Ben Roberts-Smith unlawfully killed Afghans on the field of battle have been labelled ludicrous and ridiculous on the first day of a defamation lawsuit.

Mr Roberts-Smith launched the Federal Court civil action in 2018 over media reports he says accused him of murder during his 2009 to 2012 tour of Afghanistan.

The former special forces corporal is suing the publishers of The Sydney Morning Herald, The Age and The Canberra Times over media coverage accusing him of committing unlawful killings in Afghanistan, and assaulting a woman in Canberra.

Mr Roberts-Smith denies the allegations and the media companies are relying on a truth defence.

On Monday, Mr Roberts-Smith’s barrister Bruce McClintock SC told the court his client’s reputation had been torn down by lies and “corrosive jealousy” by “bitter people” who had run a “poisonous campaign against him”.

He said other soldiers, one who was described in court as a “total failure” as a soldier, developed “enormous jealousy” at Mr Roberts-Smith’s military awards and his Victoria Cross.

“Some may call it tall poppy syndrome, others … jealousy,” Mr McClintock said.

The court heard the evidence would cover five key battlefield incidents, which took place between April 2009 and November 2012.

Mr McClintock said one of the allegations rejected was that his client shot dead a defenceless man with a prosthetic leg in an SAS attack on an insurgent compound known as Whiskey 108, in Uruzgan province.

He said the man was a member of anti-coalition militia, armed with a rifle, and it wasn’t rare for Taliban insurgents with a disability to fight on the battlefield.

“Lost limbs and prosthetic limbs are not uncommon,” he said.

Mr McClintock said another soldier, codenamed Person 6, took the prosthetic leg back to base as a trophy of war and had it mounted, then it came to be known as “das boot”.

Regarding another SAS mission, at Darwan, Mr McClintock defended his client’s actions by saying Mr Roberts-Smith followed another soldier, codenamed Person 11, up an embankment before firing at a “spotter” in a cornfield.

“He doesn’t know whether he actually hit the spotter but he may have,” Mr McClintock said.

He also described as “ludicrous” allegations Mr Roberts-Smith could have killed an unarmed man outside “in full view” on a mission.

“It didn’t happen,” he said. “Nothing could happen in secret in these missions.”

Mr McClintock also rejected claims his client ordered the execution of a prisoner after discovering a “war cache” including rockets and grenades, saying there was evidence the incident never occurred.

He also denied his client ever “blooded” soldiers, or gloated about killing an adolescent Afghan after stopping a group of men travelling in a Toyota HiLux in 2012.

Mr McClintock described as “ridiculous” claims Mr Roberts-Smith said of the alleged incident “it was the most beautiful thing I’ve ever seen”.

“It’s the kind of thing that would be said by an ostentatious psychopath,” Mr McClintock said.

“What is alleged, simply did not occur.”

Earlier, Mr McClintock said Mr Roberts-Smith was a courageous, highly organised and disciplined leader who risked his life in battle in Afghanistan in line with the SAS motto of “Who Dares Wins”.

He said despite public perceptions of war shown at times like Anzac Day, the reality was “war is violent”, describing the 2010 Battle of Tizak, in which Mr Roberts-Smith fought, as a “high water mark” for the SAS.

“This is a case about courage, devotion to duty, self-sacrifice,” Mr McClintock said in reference to his client.

Mr McClintock also rejected claims of domestic violence against his client, saying a facial injury sustained by a woman during a trip to Canberra in 2018 was not caused by his client, but rather due to the woman falling down stairs intoxicated after an official event.

“This allegation is entirely false,” Mr McClintock said.

Following Mr McClintock’s opening address, which will likely run until the end of Tuesday, it is expected the court will hear from Mr Roberts-Smith as the first witness.

Much of Tuesday’s proceedings before Justice Anthony Besanko are likely to be closed to the public due to national security evidence, the court heard.

-AAP