Clive Palmer is expected to address the High Court as it continues to hear his $30 billion battle with the state of Western Australia.
The full bench convened in Canberra on Tuesday to begin a hearing expected to span the rest of the week.
Mr Palmer is representing himself, while his company Mineralogy is being represented by barrister David Jackson QC.
It relates to extraordinary legislation passed in WA's parliament last August to amend a 2002 state agreement with Mineralogy and terminate arbitration between the two parties.
The bill, described by Mr Palmer as "draconian and disgraceful", is designed to block the Queensland mining billionaire from claiming damages from the state.
Mr Palmer is seeking up to $30 billion from WA taxpayers over a decision by the former Liberal state government not to assess one of his mining projects.
He claims the legislation, introduced by the McGowan Labor government and hastily passed with the support of opposition parties, is unconstitutional.
Mr Jackson on Tuesday said the central question of the case was the validity of the legislation, which he likened to Swiss cheese.
"It has a sufficient number of holes to make it inedible," he told the court.
Mr Palmer is expected to deliver his own verbal submissions on Wednesday.
In written submissions filed to the court, Mr Palmer argued against the legislation on several fronts including that it discriminated against a resident of another state.
"Nothing like this has ever been seen in Australia before," he said in the submissions.
Lawyers for the state of WA dismiss this claim, saying the legislation would have had the same effect if Mr Palmer were a West Australian resident.
Their submission says the legislation was passed "in order to protect Western Australians from the crippling effects" that a $30 billion damages claim would have on the state.
The federal government recently filed a notice of intervention rejecting Mr Palmer's position. NSW and the Northern Territory have also intervened in support of WA.
Queensland is not supporting either party but has submitted the legislation does not discriminate against Mr Palmer on the basis of his Queensland residency.
Victoria submits that there is no breach of Section 117 of the constitution.
The High Court last year struck out Mr Palmer's constitutional challenge to WA's hard border closures during the coronavirus pandemic.
Mr Palmer also has a defamation claim against WA Premier Mark McGowan before the Federal Court.
The pair were last week ordered to meet in "face-to-face" mediation in a bid to resolve their dispute. It is expected to happen before the end of September.
Australian Associated Press