Statements WA Premier Mark McGowan made about billionaire Clive Palmer are "not just rough-and-tumble name-calling by a politician", a lawyer for the businessman has told a Sydney court.
Mr Palmer is suing Mr McGowan claiming public comments, including labelling him the "enemy of West Australia", made in July 2020 had damaged the Queensland businessman's reputation.
The legal stoush over defamation claims got underway in the Federal Court on Monday.
The premier has lodged a counter-claim claiming the billionaire defamed him in several interviews.
Mr Palmer is expected to testify this week about the effect Mr McGowan's comments had on him, his barrister Peter Gray SC told the court.
Mr Palmer "has some experience of having harsh things said about him in the public sphere, but these attacks, these accusations, the subject of this case, are in a different league," Mr Gray said.
"They are not just rough-and-tumble name-calling by a politician."
Mr Gray said he expected Mr Palmer would give evidence about the "real and serious impact" of the particular publications on him and those around him.
In their opening on Monday, lawyers played footage to the court from media conferences Mr McGowan held in July and August 2020 and a television interview Mr Palmer gave in August the same year.
Mr Gray argued the "enemy of the state" phrase Mr McGowan used in response to a question during a press conference had a "notorious loaded significance" as an expression used by the likes of dictators Stalin and Hitler.
"It doesn't just mean opponent or someone you're having a battle or stoush with," Mr Gray said.
"'Enemy of the state' is a huge powerful, savage indictment of the person."
Mr McGowan made the comment after Mr Palmer and his company Mineralogy started High Court proceedings against WA to have the state's hard border declared unconstitutional.
Referring to Mr McGowan prefacing the comment by saying he was "happy to have a blue with Mr Palmer", the premier's barrister Clarissa Amato said: "You don't ... 'have a blue' with somebody who is the enemy of the state."
"It's quite revealing from the context, even within that narrow passage, that Mr McGowan is not speaking literally," Ms Amato told the court.
"He's talking about having some sort of figurative fight."
Ms Amato said that from the broader context that figurative fight - "in fact the real fight" - is the High Court border proceeding.
Mr McGowan had used "strong language" but in the context of a "highly charged global pandemic and a press conference", Ms Amato told the court.
Both Mr McGowan and Mr Palmer are expected to testify in person in the Sydney courtroom after Justice Michael Lee earlier said that was his preference especially during defamation proceedings.
"I think that's important for a range of reasons, including my best assessment of matters such as subjective hurt and the like," he added.
The trial will run for up to four days this week before recommencing on Saturday, February 26 so Mr McGowan and WA Attorney-General John Quigley can give evidence without missing parliamentary sittings while self-isolating for seven days when they return to WA.
Background to the case includes claims relating to the circumstances surrounding WA legislation which prevented Mr Palmer and Mineralogy from suing the state for billions of dollars.
Mr Palmer in October lost a separate High Court battle with WA over the legislation preventing him and the company suing the state.
He was seeking up to $30 billion from WA taxpayers, claiming legislation - introduced by the McGowan Labor government and hastily passed with opposition support - is unconstitutional.
The trial continues on Tuesday.
