A key soldier witness called in the Ben Roberts-Smith defamation trial won't be compelled to testify about allegedly being directed to shoot an Afghan prisoner by the war veteran.
Publisher Nine Entertainment, which is being sued by Mr Roberts-Smith over several 2018 newspaper stories, had told the Federal Court it considered the man's evidence so relevant to a truth defence it could result in winning the case.
Codenamed Person 66, the former Special Air Service Regiment (SAS) soldier was allegedly ordered by then-patrol commander Mr Roberts-Smith to shoot dead the Afghan man during a mission in Syahchow in October 2012, according to Nine's court documents.
Mr Roberts-Smith previously denied giving the order, as he denies other allegations in The Sydney Morning Herald, The Age and The Canberra Times articles of unlawful killings, bullying and domestic violence.
Person 66 objected to answering questions about missions with Mr Roberts-Smith on the grounds of potential self-incrimination, even under the protection of a certificate which would mean his evidence could not be used against him in an Australian court.
Nine wanted the witness directed to give the evidence, however Justice Anthony Besanko on Wednesday decided he should not be compelled.
"I am not satisfied the interests of justice require that Person 66 give the evidence," the judge said.
Justice Besanko said written reasons will be published at a later date.
Following Justice Besanko's decision, Person 66 was asked directly by Nine's barrister whether he shot a person under control (PUC) in October 2012 and whether Mr Roberts-Smith ordered him to do so.
The witness again objected to answering both questions, bringing his evidence to an end.
In its court documents, Nine alleges the Afghan man became a PUC in a compound before being led, with a second detainee, into a nearby field and shot.
Mr Roberts-Smith is alleged to have said, in substance, he had "blooded" Person 66 — a phrase which refers to a junior soldier recording their first kill.
A barrister for Person 66 yesterday argued his client's evidence would involve "self-incrimination of the gravest kind" and potentially expose him to the risk of charges in the future, while also affecting his wellbeing.
Nicholas Owens SC, for Nine, said Person 66's evidence was so crucial to establishing the substantial truth of imputations pleaded in the case that it represented an "independent path home to victory" for the newspapers.
Mr Owens believed it was possible for him to win the case based solely on establishing that the Syahchow incident took place, although he said it would also be possible to win the case without doing so.
When Mr Roberts-Smith gave evidence last year, he said he didn't know whether any PUCs were taken during the mission, and recalled there were two dead insurgents in vegetation following an engagement.
Assistant Defence Minister and former elite soldier Andrew Hastie, who was on the Syahchow mission, has given evidence of seeing up to 15 PUCs being questioned against a wall.
Mr Hastie, a former SAS captain, said while he was in another area, he heard a radio call stating shots had been fired and Mr Roberts-Smith later walked past him and said: "Just a couple more dead c***s."
The trial continues on Thursday with another SAS witness.