Wyong Shire Council v Shirt

Facts

The plaintiff Shirt was injured while water-skiing on Lake Munmorah, a lake controlled by Wyong Shire Council. He struck a shallow sandbank after diving from his skis in an area marked with a 'DEEP WATER' sign, which had been erected by the Council. The sign created the misleading impression that the relevant area was consistently safe for diving and water-skiing, when in fact the water depth was variable and could be dangerously shallow.

Issues

1. Whether the Council owed and breached a duty of care to the plaintiff by erecting a misleading 'DEEP WATER' sign. 2. The correct legal test for determining whether a risk is foreseeable and whether a reasonable person would have taken precautions against it — specifically, how probability of harm, magnitude of harm, and burden of precaution interact in the negligence calculus.

Holding

The High Court held that the Council had breached its duty of care to the plaintiff. The risk of injury was foreseeable and not so far-fetched or fanciful as to be disregarded, and a reasonable person in the Council's position would have taken precautions against it.

Ratio decidendi

A risk is foreseeable for the purposes of negligence if it is not far-fetched or fanciful, regardless of how low its probability. Once a foreseeable risk is established, the court must determine whether a reasonable person would have taken precautions against it by weighing the probability of the risk materialising, the likely gravity of the resulting harm, and the burden of taking precautions — no single factor is determinative and they must be weighed against each other.

Obiter dicta

Mason J observed that the weighing of these factors does not produce a rigid formula, and that the magnitude of the risk and the gravity of potential harm may, in some cases, be so significant that precautions are required even where the probability of the risk occurring is quite low. He also noted that the standard of the 'reasonable person' does not demand perfection but requires only the care that a reasonable person exercising ordinary prudence would take.

Significance

Wyong Shire Council v Shirt is the foundational Australian authority on the calculus of negligence, establishing the multi-factor balancing test for breach of duty of care that underpinned Australian negligence law until the civil liability legislation reforms of the early 2000s, and its reasoning continues to inform the statutory formulations of breach in those Acts.

Key authorities

• Bolton v Stone Bolton v Stone [1951] AC 850considered
• Glasgow Corporation v Muir Glasgow Corporation v Muir [1943] AC 448considered
• Wagon Mound (No 2) Overseas Tankship (UK) Ltd v The Miller Steamship Co Pty Ltd (Wagon Mound No 2) [1967] 1 AC 617considered
• Haley v London Electricity Board Haley v London Electricity Board [1965] AC 778considered