Australia: High Court Confirms That A Defendant Need Only Exercise Reasonable Care Rather Than Prevent Harm

Last Updated: 4 April 2008
Article by Kathy McCarthy and Peter Swingler

This is a decision of the High Court which considers, among other things, the duty of care owed by a roads authority, how a breach is to be assessed and also contributory negligence.


  • On 31 December 1998, Philip Dederer ("Dederer"), who was then 14, dived from a bridge across the Wallamba River in New South Wales. He steadied himself by holding on to a lamppost and dived from the highest of three horizontal railings on the side of the bridge. The top of the railing was flat and about nine metres above the surface of the water. He struck a submerged sandbank and was rendered partially paraplegic.
  • There were pictograph signs on the approaches to the bridge prohibiting diving, and signs in words prohibiting climbing on the bridge. Dederer saw and understood the signs before he dived but he chose to disregard them.
  • The pictograph signs were erected by the Great Lakes Shire Council ("the Council") in 1995, with funding obtained from the Roads and Traffic Authority of New South Wales ("the RTA").
  • While the statutory functions of the Council and the RTA were not fully considered at trial or in the Court of Appeal, it was concluded that the RTA was responsible for the erection and maintenance of the bridge and that the Council was responsible for the day to day management of the bridge including, among other things, the enforcement of the prohibition contained in the various pictographs and signs.
  • There was evidence that the practice of jumping and diving from the bridge had been widespread in the 40 years prior to the accident. However, there was no evidence that anyone had previously been injured in doing so.

Initial Trial

  • At the initial trial, the trial judge found for Dederer against both the RTA and the Council. However, his Honour also held that Dederer had been guilty of contributory negligence and assessed his responsibility for his injuries at 25%.
  • As between the RTA and the Council, his Honour found that the RTA was 80% responsible for Dederer's damages (after the deduction for contributory negligence) and the Council 20%. The quantum of damages was not in issue and judgment was entered for Dederer in the sum of $1,050,000.
  • In the result, his Honour concluded that the RTA and the Council should bear 60% and 15% respectively of the responsibility for Dederer's injuries and damages, and Dederer himself 25 per cent.

Court of Appeal

  • The Court of Appeal was satisfied that the practice of diving from the bridge was so widespread that the RTA must be taken to have known of the practice.
  • The majority accepted that the "no diving" signs were ineffective. As a result, it was held that the RTA was in breach of its duty of care, by failing to take further steps to prevent injury to persons such as Dederer.
  • Their Honours referred to Wyong Shire Council v Shirt. The majority were of the view that the RTA's reasonable response to the risk should have been to install swimming pool fencing (vertical posts without horizontal cross members) and to modify the top railing by adding to it an upward facing triangular section so as to make it more difficult to climb on to and balance on the top before diving.
  • As to the trial judge's holding that the RTA should have erected a "Danger, shifting sands, variable depth" warning sign, the majority of the Court of Appeal thought a composite sign containing the "no diving" pictograph with the words "shallow water" was preferable and should have been erected.
  • The majority of the Court of Appeal also adjusted the trial judge's assessment of Dederer's responsibility for his injuries, increasing it from 25% to 50%.

High Court

Scope of the RTA's duty of care

  • The High Court stated that duties of care are not owed in the abstract. Rather, they are obligations of a particular scope, and that scope may be more or less expansive depending on the relationship in question. However, whatever their scope, the High Court said that all duties of care are to be discharged by the exercise of reasonable care. They do not impose a more stringent or onerous burden.
  • The Court held that the obligation to exercise reasonable care must be contrasted with an obligation to prevent harm occurring. The law requires the exercise of reasonable care but does not impose an obligation to prevent harm occurring.
  • The Court said that the question of whether reasonable care was exercised is to be adjudged prospectively, and not by retrospectively asking whether the defendant's actions could have prevented the plaintiff's injury.
  • It was found that the risk of injury consequent upon jumping or diving from the bridge into water of variable depth was reasonably foreseeable.
  • The Court said that while the magnitude of the risk was self-evidently grave, the probability of that injury occurring was low. This was because, despite the frequency of people jumping and diving from the bridge, no-one had been injured until Dederer's dive.

Were the precautions reasonable ?

  • The High Court said that there has to be a balancing of the magnitude of the risk, the degree of probability of its occurrence, and the expense, difficulty and inconvenience of taking alleviating action, and any other conflicting responsibilities of the defendants.
  • While the erection of further warning signs would not have been expensive, it was found that Dederer provided no evidence that they would be reasonable.
  • Two other preventative measures that had been suggested were a triangular cap on the handrail to make it harder to stand on and the installation of pool-type fencing. However, the Court held that with estimated costs of $108,072 and $150,000 respectively, the reasonableness of these measures was open to doubt.

Did the RTA breach its duty of care ?

  • Applying the assessment of breach mandated by Wyong Shire Council v Shirt, the Court found that the RTA did not breach its duty of care.
  • The High Court held that a proper balancing exercise which takes account of all of the relevant circumstances into account lead to the conclusion that the RTA, in responding to a risk that had not been realized in 40 years, by erecting the pictograph signs, acted reasonably and adequately.
  • It found that though grave, the risk faced by Dederer was of a very low probability and a reasonable response to that risk did not demand the measures suggested by him.
  • The Court said that those measures lacked evidential support, were of doubtful utility and would have caused significant expense in the case of the modifications to the handrail and fencing.
  • The High Court also did not accept the views of the lower courts that youths would have heeded a worded sign when they flagrantly disregarded a pictograph sign with a clear meaning.
  • It was found that this was not a case in which the RTA had done nothing in response to a foreseeable risk. To the contrary, the RTA had erected signs warning of, and prohibiting, the very conduct engaged in by Dederer. In the circumstances, that was a reasonable response.


  • This decision should give some comfort to insurers.
  • In confirming its previous decision in Wyong Shire Council v Shirt, the High Court has confirmed that duties of care are discharged by taking reasonable care rather than preventing harm occurring.
  • The Court also confirmed that there needs to be a balancing of the magnitude of the risk, the degree of probability of its occurrence, and the expense, difficulty and inconvenience of taking alleviating action, and any other conflicting responsibilities of the defendants.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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