Mineralogy Pty Ltd v Western Australia

Mineralogy Pty Ltd and other co-proponents commenced proceedings in the High Court of Australia's original jurisdiction against the State of Western Australia. The dispute concerned the validity of the *Iron Ore Processing (Mineralogy Pty Ltd) Agreement Amendment Act 2020* (WA) (the Amending Act), which purported to amend an earlier State Act and an agreement scheduled to it. The plaintiffs sought declarations that the Amending Act was invalid, alleging it contravened the *Australia Act 1986* (Cth), exceeded the State Parliament's legislative power by infringing the rule of law or deeply rooted common law rights, and was incompatible with Chapter III of the Australian Constitution and section 118 of the Constitution. The parties agreed to state questions of law for the Court's determination by way of a special case.

The High Court was required to determine several legal issues. These included whether the Amending Act was invalid in its entirety, and if not, whether specific provisions, particularly those that would deprive certain proposals of legal effect and arbitral awards of legal effect, were invalid or inoperative. The Court also had to consider whether any invalid provisions were severable. Furthermore, the Court was asked to determine if the facts and documents presented in the special case were sufficient to necessitate answering the stated questions of law for the determination of the parties' immediate rights, duties, or liabilities.

The Court reasoned that the Amending Act was not invalid in its entirety. It found that sections 9(1) and 9(2), and sections 10(4) to 10(7) of the *Iron Ore Processing (Mineralogy Pty Ltd) Agreement Act 2002* (WA), as inserted by the Amending Act, were not invalid or inoperative. The Court considered that the remaining questions regarding the invalidity of other provisions were unnecessary to answer given this conclusion. The Court also determined that the question of severability did not arise. The Court ultimately answered the questions posed in the special case as proposed in the joint judgment.