Construction Forestry Mining & Energy Union v Mammoet Australia Pty Ltd ACN 075 483 644

The High Court of Australia considered an appeal from the Full Federal Court concerning the interpretation of a workplace determination made under the *Building and Construction Industry Improvement Act 2005* (Cth) (BCII Act). The dispute involved the Construction, Forestry, Mining and Energy Union (CFMEU) and Mammoet Australia Pty Ltd (Mammoet), an employer engaged in the construction industry. The core of the disagreement lay in whether Mammoet was obligated to pay its employees redundancy entitlements as stipulated by the workplace determination, even though Mammoet had ceased operations and its employees had been terminated prior to the determination taking effect.

The central legal issue before the High Court was whether the workplace determination, which prescribed redundancy payments, had retrospective operation such that it applied to employees whose employment had been terminated before the determination was made. Specifically, the Court had to determine if the language of the determination, read in light of the BCII Act, evinced a clear intention to alter the rights and obligations of parties in relation to past events, particularly concerning accrued entitlements or entitlements that arose upon termination of employment.

The High Court held that the workplace determination did not have retrospective effect. The Court reasoned that legislative instruments, including workplace determinations, are presumed to operate prospectively unless there is a clear and unambiguous intention to the contrary. Applying this principle, their Honours found that the language of the determination did not indicate an intention to apply to terminations that had already occurred. The Court emphasised that the BCII Act did not confer power to make determinations with retrospective effect in a manner that would override this presumption. Consequently, Mammoet was not obliged to pay redundancy entitlements under the determination to employees whose employment had ceased before the determination came into force.