Federal Court Justice Darryl Rangiah has endorsed WA's hard border closures as the most effective way of preventing the potential import of coronavirus.

But the saga is far from over with the High Court to determine Mr Palmer's claim that the restrictions are unconstitutional.

Mr Palmer has confirmed he has no intention of dropping the challenge, which is likely to be heard by the High Court in October.

"We've decided we should test the law on it," Mr Palmer told Perth radio 6PR on Wednesday.

The billionaire mining magnate also plans to launch proceedings in the High Court against Mr McGowan and Attorney-General John Quigley for contempt of court.

It comes after WA's parliament passed an extraordinary bill to amend a 2002 state agreement with Mr Palmer's Mineralogy company and terminate arbitration between the two parties.

The legislation is intended to prevent Mr Palmer from proceeding with an almost $30 billion damages claim against the state over a 2012 decision not to assess one of his mining projects.

"They bought in this act of parliament which is unconstitutional, mainly as a punishment because I was taking a point of law to the High Court," Mr Palmer said.

"You can't do that, you can't attack your opponent, your litigant, just to try to stop them from exercising their normal rights."

Mr McGowan said he had lost track of the number of lawsuits Mr Palmer had launched involving the state.

"I think a reasonable person would have pulled back after yesterday's judgment," he said.

Justice Rangiah delivered his reserved decision on Tuesday after being tasked with establishing key facts in the borders dispute.

He found the hard borders were stronger than any alternative approach to keeping COVID-19 out of the state, including the "hot spot" regime which the federal government initially advocated for before withdrawing from the matter.

Justice Rangiah said a precautionary approach should be taken, given an uncontrolled outbreak could have catastrophic health consequences.

However, the judgment did not take into account economic or social impacts or address the issue of constitutionality.

Mr Palmer launched his border challenge after he was denied an exemption to enter WA.

It later emerged he had offered to withdraw the case if unrelated arbitration hearings were relocated from Perth to Canberra.

WA again had no new virus cases on Wednesday. Eight cases remain active.

Australian Associated Press