Liberal Senator Linda Reynolds intends to claim that Brittany Higgins and her now fiance David Sharaz colluded with Lisa Wilkinson and a Network 10 producer to politically attack her, if her defamation cases against the couple go to trial.

The former defence minister, who plans to retire from politics at the next election, is suing her former political staffer and Sharaz over a series of social media posts that she says have damaged her reputation.

Lawyers for the parties appeared in the Western Australian Supreme Court on Wednesday, after a closed-door mediation hearing failed last month, as the matters edged closer to trial.

They wrangled over how the prospective trials should be run, with Senator Reynolds’ lawyer Martin Bennett saying they were so “intertwined” they should be partially merged to prevent duplication and save the parties money.

This includes potentially having witnesses common to both cases appear only once and running the trials together, with Sharaz’s case starting first but no firm decisions were reached and mediation could be restarted.

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“This is two major pieces of litigation listed for a lengthy period of time between three individuals, these are not media organisations,” Bennett told the court.

Outside the court, Bennett said the defamation action was costing 58-year-old Reynolds “a fortune”.

“My client mortgaged her home at her age to pay for legal fees to do this to try to vindicate her reputation,” he said.

“It costs individuals a lot of money to do this.”

In court, Bennett read out examples of duplication in Higgins’ and Sharaz’s court documents, while referring to the West Australian senator’s claim for aggravated damages.

He said it included details about a plan allegedly initiated by Sharaz and Higgins, with help from Network Ten star Wilkinson and producer Angus Llewellyn “to attack my client”.

Bennett also said that “during the period of time Ms Higgins was in Perth working on the plaintiff’s federal election campaign (in 2019), she felt isolated and was in a state of depression,” as he cited another example of overlap between the two cases.

Reynolds would call witnesses to rebut that claim, he said.

Bennett said Wilkinson and Llewellyn could be called as witnesses and that audio of a five-hour meeting, in which they allegedly discussed a plan with Higgins and Sharaz, had been subpoenaed.

In Higgins’ interview with Wilkinson, aired on Ten’s The Project in February 2021, she claimed another Liberal staffer Bruce Lehrmann had raped her in Reynolds’ Parliament House office in 2019.

Lehrmann has consistently denied that allegation.

Reynolds is also attempting to access a transcript from Lehrmann’s defamation battle with Ten and Wilkinson in the Federal Court in Sydney.

Bennett also said Higgins had published a social media post saying “I won’t stay silent so you can stay comfortable” amid last month’s mediation, adding that it would bolster Reynolds’ claim for aggravated damages.

Bennett said Reynolds was likely to call 17 to 20 witnesses if the trial goes ahead, which was previously provisionally listed for six weeks from July 24.

The matter will return to court on May 24.

-AAP