A lawyer for Clive Palmer has labelled John Quigley an unreliable witness after it emerged the West Australian attorney-general is seeking to correct evidence he gave in a defamation trial.
The application came to light on Thursday, two weeks after Mr Quigley testified as a witness in the Federal Court matter.
Mr Palmer is suing WA Premier Mark McGowan for defamation, claiming public comments - including labelling the billionaire the "enemy of the state" - had damaged his reputation.
The premier has lodged a counter-claim that he was defamed in several of Mr Palmer's interviews and statements.
An affidavit submitted to the court this week reveals Mr Quigley wants to correct "mistakes" made during his oral evidence.
The 73-year-old had been accused by Mr Palmer's lawyers of providing false evidence during the cross-examination, an assertion he denied.
Mr McGowan's barrister, Bret Walker SC, on Thursday told Justice Michael Lee it would be appropriate for the witness to be re-examined.
But Mr Palmer's lawyer, Barry Dean, said Mr Quigley was effectively asking for a "do-over", noting that a week had passed between his testimony and the government's lawyers receiving notice that he wanted to correct his evidence.
"Your honour will need to consider and assess the credit of this witness," Mr Dean said.
"There will be criticisms of this witness, and those criticisms should have been obvious from anyone who saw the previous evidence.
"There's no way your honour, in my submission, can find that this is a reliable witness."
Mr Dean noted the attorney-general had made repeated references to being under oath when he gave his evidence.
Justice Lee declined to make an immediate ruling but said the only basis on which he would receive further material from Mr Quigley would be via oral evidence.
This would involve being subject to further cross-examination, he added.
Mr Quigley's testimony mainly focused on extraordinary legislation introduced by the government in August 2020 to prevent Mr Palmer from suing the state.
Mr Palmer had been seeking up to $30 billion in damages over a 2012 decision by the former Liberal state government not to assess his proposed Balmoral South iron ore mine project.
The court heard Mr Quigley had privately proposed to the premier that they conceal a "poison pill for the fat man" within a legislative amendment.
The bill was introduced late in the day and other cabinet ministers were only told about it 45 minutes beforehand.
But in his evidence, Mr Quigley repeatedly denied being aware of the possibility Mr Palmer might try to register his arbitration awards in court if he became aware of the government's plans.
That assertion was rubbished by Mr Palmer's lawyers during the cross-examination.
In private messages shown to the court between the premier and attorney-general, Mr Quigley labelled Mr Palmer a "big fat liar", saying he was "looking forward to dumping on Palmer in statesman-like way".
Mr McGowan also faced extensive questioning, having privately described the Queensland businessman as "the worst Australian who's not in jail."
Justice Lee is expected to hear closing submissions next month.
