Impiombato v BHP Group Limited

In the case of Impiombato v BHP Group Limited, the appellants, led by Impiombato, challenged interlocutory decisions made by Moshinsky J in the Federal Court of Australia regarding the interpretation of the definition of group members in a representative proceeding against BHP Group Limited. The proceeding alleges breaches of the Australian Securities and Exchange Commission (ASIC) Listing Rules, Corporations Act, and misleading and deceptive conduct provisions under both the Corporations Act and the Australian Securities and Investments Commission Act. The dispute centers on the interpretation of the group member definition in the context of the representative proceeding, specifically whether it includes shareholders who traded on platforms other than the Australian Securities Exchange, London Stock Exchange, or Johannesburg Stock Exchange. The appellants argued that the definition should encompass all shareholders during a specified period, while BHP Group Limited contended that it should be limited to those trading on the designated exchanges.

The central legal issues before the court were the interpretation of the group member definition as set out in the originating application and the statement of claim, and the appropriateness of the timing for the amendments to these documents to take effect. The court had to determine whether the primary judge correctly interpreted the group member definition and whether the discretionary decision to set the amendments' effective date was based on material errors of fact. The court also considered the principles articulated by the Full Court in Ethicon Sàrl v Gill, which address the timing of amendments in representative proceedings.

The court found no error in the primary judge's interpretation of the group member definition, affirming that it was correctly understood to exclude shareholders who traded on platforms other than the specified exchanges. However, the court did find that the primary judge's decision on the timing of the amendments' effective date was based on material errors of fact. As a result, the court allowed the appeal and re-exercised the discretion, determining that the amendments to the group member definition should take effect from the date they were made, while amendments to the claims of existing group members should take effect from the commencement of the proceeding. The court set aside the previous order and specified new effective dates for the amended documents, and ordered written submissions on the costs of the interlocutory application and appeal to be filed by a specified date.

The court's final orders included allowing the appeal, setting aside the previous order, specifying new effective dates for the amended documents, and directing the parties to file written submissions on the costs of the interlocutory application and appeal. The court's decision clarifies the interpretation of the group member definition and the appropriate timing for amendments in the context of a representative proceeding, while also addressing the procedural aspects of the case.