Mulligan v Coffs Harbour City Council

The High Court of Australia heard an appeal from the plaintiff, Mulligan, against the Coffs Harbour City Council and the State of New South Wales. The dispute concerned injuries sustained by the plaintiff when he dived into a channel within a tidal creek and struck a submerged sand dune, resulting in a broken neck. The plaintiff alleged that the respondents negligently failed to erect warning signs about the dangers of diving in the channel.

The central legal issues before the High Court were whether the respondents owed a duty of care to the plaintiff and, if so, whether they breached that duty by failing to erect signs warning of the risk of striking submerged objects in the channel. The court was required to consider the foreseeability of the risk of injury and the relevance of the obviousness of the risk to the questions of duty and breach in the context of a local authority's management of a natural reserve.

The High Court, in dismissing the appeal, reasoned that the presence of sand dunes (bedforms) in the tidal channel was a natural and well-known phenomenon, subject to constant change due to tidal movements. The court found that the proliferation of these bedforms was within normal and naturally occurring limits for a tidal estuary of that nature. Applying principles of negligence, the court concluded that a reasonable local authority would not have been expected to erect warning signs in these circumstances, as the risk was not so specific or unusual as to warrant such a measure. The obviousness of the potential for submerged objects in a tidal waterway was also a significant factor in determining that no duty to warn had been breached.