Queensland Alumina Ltd v Alinta DQP Pty Ltd

The case before the court involved a dispute between Queensland Alumina Limited and Alinta DQP Pty Limited. The crux of the matter was the contractual agreement between the parties regarding the supply of gas, which was expressly subject to a statutory instrument. Despite the agreement on the rate payable, the statutory instrument imposed a cap on the amount that could be charged. Over time, the plaintiff remitted payments that exceeded this statutory limit. The primary legal issues were whether the agreed terms and the statutory instrument were inconsistent and, if so, which would prevail, as well as whether an estoppel or a mistake precluded the plaintiff from recovering the overpaid amounts.

The court began by examining the contractual language and the statutory instrument to determine whether they were reconcilable. The court found that the statutory limit on charges was mandatory and unambiguous, thus overriding the agreed terms in the contract. This statutory provision was held to be a clear expression of legislative intent to cap the charges, and therefore, it prevailed over the contractual agreement. Regarding the estoppel, the court held that the defendants could not be estopped from denying the plaintiff's claim for recovery because the plaintiff's conduct did not meet the necessary criteria for estoppel. As for the restitution based on mistake, the court found that the plaintiff was not mistaken about the terms of the payment, and therefore, the moneys were not recoverable under a mistake of fact.

Consequently, the court ruled in favour of the defendants, finding that the plaintiff was not entitled to recover the overpaid amounts. The court ordered that judgment be entered for the defendants with costs, including any reserved costs.