Mr Russell is suing the national broadcaster over two articles, from October 2020 and November 2021, that claimed commandos from the platoon he led executed an unarmed prisoner in Afghanistan in mid-2012 because there was no room on a helicopter.
The second ABC article reported an investigation into the platoon had been confirmed by the defence department when it had not been and linked to the earlier article.
Mr Russell was named as platoon leader by the broadcaster.
He denies the allegations and is suing for damages, saying his reputation was ruined and his feelings hurt by the reporting.
His barrister Sue Chrysanthou SC told the Federal Court on Tuesday the ABC seriously harmed Mr Russell's public standing and had admitted doing so.
The articles by journalists Mark Willacy and Josh Robertson were wrong, she said, and the ABC could not prove the allegations, forcing it to rely on a defence that publishing them was in the public interest.
Mr Russell acknowledged the publications concerned issues of public interest, but Ms Chrysanthou said that was not the reason later articles went online.
"There was a significant body of evidence which demonstrates these articles were a PR exercise," she said.
The article claiming defence had confirmed an investigation into the platoon's conduct was based on a Freedom of Information request being denied and the department had not provided any confirmation.
That story was merely "ego protection" for Willacy after criticism from rival media outlets he described as "bottom feeders", Ms Chrysanthou said.
In addition, nobody could explain who was responsible for a press release accompanying the later article and why it was issued, she said.
ABC Investigations put itself forward as an "elite group of award-winning journalists" and knew its reporting would be treated as credible, requiring it to be held to a higher standard.
"There is no public interest in being lied to by the ABC about a serious allegation of murder in relation to a group of soldiers who were not afforded the opportunity to even respond," Ms Chrysanthou said.
Closing addresses in the trial continue before Justice Michael Lee.
He said the awarding of damages could depend on whether he found Mr Russell lied in his evidence and whether his claim of hurt feelings was believed.
"I have significant reservations about accepting his evidence on any matter that is contested," Justice Lee said.
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