The mining magnate, Clive Palmer, has instructed his lawyers to commence a high court challenge against the Queensland government’s ongoing border closure.
The court on Thursday afternoon heard that a similar case launched by Palmer, challenging the Western Australia border closure, would likely take at least six weeks to proceed to a hearing in mid-July.
Peter Dunning QC, representing Palmer, told the court it was hoped the cases could dovetail.
Both states have said publicly that border closures are based on health advice, and that they will likely keep the measures in place for several months.
The high court chief justice, Susan Kiefel, advised Palmer’s lawyers to consider the mining multimillionaire’s standing to bring a case against his home state, given his own movement is not restricted by the border closure.
Dunning said the closure had affected Mineralogy, Palmer’s flagship company.
Earlier Joshua Thompson, Western Australia’s solicitor-general, told the court the state may seek to present to the court “opinion evidence” to establish the reasonableness of the state’s border closure and its effect in preventing the spread of the Covid-19 virus.
“The establishment of the constitutional facts-related reasonableness of the [border closure] measures is on the defendants [the state of Western Australia] … in this case. If you can’t, the validity of the measure has not been established.
“That’s why we will have some significant evidence in relation to that … that will require some evidence about a number of different things and some of those things may not be capable of statistical quantification.”
Palmer launched the proceedings after being denied entry to Western Australia this month.
Before the court hearing on Thursday, Palmer released a statement calling the border closure in Queensland “an injustice”.
“I am duty-bound to show solidarity towards and do whatever is in my power to help those who are now unemployed and have businesses that have been adversely affected,” he said of the imminent Queensland challenge.
“Opening the borders in Queensland will provide the boost needed to return jobs and prosperity to this state.
“[The premier] Annastacia Palaszczuk is discriminating against her own people by locking away the fruits of Queensland such as the Great Barrier Reef and other treasures from interstate visitors.”
Palaszczuk has said the border closure could remain in place until September and that it was based on the advice of the state’s chief health officer.
The prime minister, Scott Morrison, on Wednesday said that states with closed borders needed to justify the decision with public health advice.
While Queensland residents are not able to travel long distances or take overnight trips within their own state, authorities say they will not stop residents from entering New South Wales next week to take advantage of newly-relaxed restrictions south of the border.
The situation means a Brisbane resident can potentially visit Albury 1,400km away but not lawfully travel north of Noosa, from 1 June.
The Queensland health minister, Steven Miles, the health department and police each advise residents they should only cross the border to leave the state for an essential purpose, but after questions from Guardian Australia police confirmed they were not stopping any Queenslanders from leaving or returning.
Only those who have visited coronavirus “hotspots” – of which there are none in NSW – would be required to self-isolate for 14 days on return.
“The actions of a person within another state in relation to Covid-19 are subject to that state’s chief health officer and enforcement agency,” a police spokesman said.
Current Queensland regulations limit people to travel within 150km of their homes, or 500km if they live in outback areas. No overnight tourism is allowed until 13 June.
From 1 June, New South Wales will allow travel to regional areas in an attempt to restart its local tourism industry.
More than 3 million Queenslanders live within 150km of the New South Wales border and could cross without breaching the existing local restrictions.
Miles told Guardian Australia that the state’s border restrictions were in place to keep Queenslanders safe.
“There is still community transmission in Sydney and Melbourne,” Miles said. “What we don’t want to see is that spread to Queensland
“So far, Queenslanders have done an incredible job following the directions and limiting their movements.
“We’re asking Queenslanders not to cross the border, unless for an essential service.
“As the restrictions are lifted, let’s take an inch not a mile. On 13 June, Queenslanders can holiday in Queensland within 150km of their home.
“If we all keep following the rules, restrictions will continue to be lifted.”