Victorian Liberals leader John Pesutto says he called for the expulsion of Moira Deeming because he needed to protect his party from reputational damage.
Ms Deeming claims Mr Pesutto defamed her in media releases, a press conference and broadcast interviews after she attended a Let Women Speak rally in March 2023.
The rally was gatecrashed by neo-Nazi's who performed the Nazi salute on the steps of the state parliament.
Ms Deemings barrister, Sue Chrysanthou SC cross-examined Mr Pesutto on Tuesday over a 15-page dossier he prepared and forwarded to party members calling for Ms Deeming's expulsion.
She submitted that given Mr Pesutto's legal background, he should have known better than to copy and paste or screenshot information from social media and news reports without including the full context.
His dossier, which highlighted the views and beliefs of Ms Deeming's associates, and the subsequent expulsion of Ms Deeming "fell short" of judicial process.
"Cutting and pasting part of an article, without context ... was unfair to do that," Ms Chrystanthou told the Federal Court.
She then compared the dossier to a project prepared by an eight-year-old - a statement Mr Pesutto rejected.
He told the court he was satisfied that his leadership team had enough information.
"I wasn't (doing this as) a lawyer, I was the leader of the opposition, the alternative premier, there were many other considerations," Mr Pesutto said.
"There were grave reputational risks to the party.
"Public tension about the events on the Saturday were mounting ... it was clear the issue was escalating and I thought it was time to act."
Mr Pesutto later told the court that he was "surprised" his deputy leader David Southwick had recorded a meeting between the leadership team and Ms Deeming before the decision to try to expel her from the party.
Once he was made aware of the recording, Mr Pesutto didn't ask for a copy nor did he ask if Mr Southwick had any other secret recordings.
During another line of questioning, during which Ms Chrystanthou repeatedly reminded him to answer questions and not make speeches, Mr Pesutto conceded if he had his time again he "might do things differently".
Asked whether the party's beliefs should change depending on its leader at the time, Mr Pesutto agreed.
"You were elected by one vote," Ms Chrystanthou said.
"So what? So what?" Mr Pesutto replied.
Earlier on Tuesday, Mr Pesutto's barrister Matthew Collins KC said the damage was done well before the opposition leader made any comments or moved to expel Ms Deeming from the party.
The barrister provided examples of tweets sent to Ms Deeming drawing links to rally organisers and Nazi sympathisers, as well as others sent to Mr Pesutto calling for him to axe Ms Deeming from the party.
He agreed Ms Deeming's reputation had been tarnished, but said it had "nothing to do with Mr Pesutto".
"It (her reputation) suffered that damage by reason of her conducting, organising, promoting and speaking at the rally," he said.
Video footage of the rally, including chants and Nazi salutes was described by Dr Collins as "utterly chilling" and he said the appropriate response for a member of a mainstream political party was to loudly and clearly denounce it.
Instead, he said Ms Deeming was shown in videos drinking champagne with organisers and indulging in "bizarre conspiracy theories" after the rally.
"Politics is a rough game," Dr Collins told the court, arguing political parties needed to secure the mainstream vote to win elections.
"Associations of this kind are absolutely toxic, it drives people from the centre a mile away and that's why he acted."
Mr Pesutto will continue giving evidence on Wednesday.
