The 28-year-old spectacularly lost his Federal Court defamation case against Ten and journalist Lisa Wilkinson earlier in April.

In a move claimed by Ten to have been “deliberately wicked and calculated,” Lehrmann alleged a February 2021 report on The Project ruined his reputation by falsely claiming he raped Brittany Higgins in a Parliament House office almost two years earlier.

Justice Michael Lee found, on the balance of probabilities, Lehrmann had raped Ms Higgins because she had been too intoxicated to consent.

In submissions made public on Tuesday, the ex-Liberal staffer’s barrister David Helvadjian said the court should decide how legal costs were split among the parties.

But Mr Helvadjian contended that Lehrmann still acted reasonably in bringing the lawsuit to vindicate his reputation, despite the loss.

“(The) allegation was of serious criminal conduct, the allegation had not been established in any criminal proceedings, the respondents bore the onus of proof, and (Lehrmann) disputed the truth of the allegation,” he wrote.

Ten and Wilkinson had also not proven they had acted reasonably in producing the report after failing to investigate a number of shortcomings in claims put forward by Ms Higgins, Mr Helvadjian said.

Her allegations that were rejected by Justice Lee included claims of a government cover-up of the rape.

Despite the warning signs, Wilkinson and Ten producer Angus Llewellyn proceeded with an “active ignorance” in running the full story, Mr Helvadjian said.

This meant Ten and Wilkinson should be on the hook for at least part of Lehrmann’s costs, the barrister added.

Ten has rejected this, arguing its defence was not “doomed to fail”.

The network’s barrister Matt Collins KC wrote that Lehrmann’s conduct was so bad in bringing the lawsuit that he should be hit with indemnity costs.

“Mr Lehrmann brought this proceeding on a deliberately wicked and calculated basis,” he wrote.

“He put Network Ten to the cost of defending this proceeding, which can be, with the benefit of hindsight, described as a clear abuse of process aimed at concealing the truth that Mr Lehrmann raped Ms Higgins.”

The 28-year-old brought the lawsuit on a false basis to rehabilitate his reputation, the barrister added.

“Mr Lehrmann engaged in an abuse of the court’s processes, ran a case based on positive falsities, and put Network Ten to the cost of defending a baseless proceeding.”

Lehrmann also unreasonably rejected a “walk away” settlement offer made by Ten in August 2023 despite a very real prospect his case would fail, Dr Collins wrote.

“It must have been apparent to Mr Lehrmann, as at the date of the offer, that the chickens were coming home to roost.”

Under the offer, Ten proposed that each party would consent to dismiss the case and bear their own legal costs.

Wilkinson’s barrister Sue Chrysanthou SC argued Lehrmann should also foot the legal bill for her client given his “highly disreputable conduct”.

“Ms Wilkinson has obtained judgment in her favour, and the applicant has wholly failed,” she wrote.

The costs hearing will be heard before Justice Lee on May 1.

1800 RESPECT (1800 737 732)

National Sexual Abuse and Redress Support Service 1800 211 028