By Miklos Bolza in Sydney

Brittany Higgins was so obsessed with pursuing Bruce Lehrmann over an alleged sexual assault that she refused to help Ten defend his defamation case unless they agreed not to settle, his lawyers say.

In a submission made public on Friday, Lehrmann’s side argues Ms Higgins’ credibility is so poor the court should completely reject her testimony unless it is corroborated by some other source.

“No confidence can be placed in Ms Higgins’ understanding of her obligation to tell the truth under oath or on the most solemn of occasions,” Lehrmann’s submission said.

Ms Higgins had a “preparedness to tell lies” both to the federal government to obtain a “life changing” settlement of almost $2.5 million and to an ACT criminal court during a now-dropped prosecution of Lehrmann, the document said.

The former Liberal media adviser had an “obsession” with securing vindication against her claimed rapist through the courts, including in his defamation case against Network Ten, the submission argued.

Ten returned fire in its submissions, branding Lehrmann a liar who had concocted a story about the night of the alleged rape to deter police from charging him.

Lehrmann is suing Ten and journalist Lisa Wilkinson over a February 2021 report on The Project in which Ms Higgins was interviewed about her alleged rape in Parliament House.

She claims Lehrmann sexually assaulted her in the office of their then boss, Senator Linda Reynolds, in March 2019.

In agreeing to help Ten defend the defamation case, Ms Higgins said the network was not to make any offer to Lehrmann to pay him damages, retract the articles, make an apology or pay his legal costs.

“That is an extraordinary position for a witness to take,” Lehrmann’s submission said.

In the document, Lehrmann continued his denials that any sexual activity took place, saying there were “too many other plausible possibilities” about what happened and why Ms Higgins was later found naked in Senator Reynolds’ office.

She could have vomited on her dress and removed it or taken it off because she was afraid of soiling it, the submission said.

“The critical point is there are a number of plausible explanations for why Ms Higgins, being affected by alcohol, took off her dress and lay down naked on the minister’s couch.”

Ten, in its submission, said Lehrmann’s denials were designed to deter any charges being brought against him.

“It was a rational approach for a liar to take in circumstances where he had resolved to participate in an interview with police in the hope that it would result in them not pursuing the matter further,” the broadcaster’s lawyers wrote.

Ten argued the ex-Liberal staffer was not entitled to even nominal damages in a situation where his reputation had not suffered any harm or he had engaged in “disentitling” conduct.

Wilkinson said, in her submission, that if sexual activity was found to have taken place, an award of damages to Lehrmann would “scandalise” the court.

“In this case, if the court finds that (Lehrmann) had sexual intercourse with Ms Higgins and lied about it to the police, the public, the chief justice and the jury, and this court, that is an abuse of process,” the journalist’s submission said.

Lehrmann also sued News Corp and the ABC over their coverage of Ms Higgins’ allegations.

Both these cases have settled, with the ex-Liberal staffer receiving $445,000 in legal costs under the agreements.

The trial against Ten has concluded and judgment will be delivered at a later date.

Lehrmann was charged in August 2021 over the alleged rape, but his criminal trial in the ACT Supreme Court was derailed by juror misconduct.

Prosecutors did not seek a second trial, citing concerns for Ms Higgins’ mental health.

Lehrmann is also before Queensland courts accused of raping another woman twice in Toowoomba in October 2021.

He has not yet entered a plea, but his lawyers have indicated he denies the charges.