Australia: Rebutting the statutory presumption of contributory negligence: Is it objective, subjective or - impossible?

Last Updated: 28 December 2015
Article by Peter Jones and Nadia Stanev

On 9 December 2015, the High Court delivered an important judgment in the context of personal injury claims arising out of motor vehicle accidents in South Australia.


The decision concerns the operation and interpretation of Parts 6 and 7 of the Civil Liability Act 1936 (SA) which construct a regime for determining negligence and create a presumption of contributory negligence where:

  • The injured person has relied on the care and skill of a driver who they knew or ought to have known was intoxicated – Section 47(1);
  • The injured person was not wearing a seatbelt as required under the Road Traffic Act 1961 – Section 49(1)(a).

The relevant provisions mandate the application of a fixed statutory reduction of either 25% or 50% depending on the negligent driver's blood alcohol concentration, and 25% in the case of failure to wear a seatbelt.

The presumption that arises in circumstances involving driver intoxication may be rebutted by establishing, on the balance of probabilities, that "the injured person could not reasonably be expected to have avoided the risk" – Section 47(2)(b).


Ms Chadwick, aged 21, and Mr Allen, aged 28, had been in a relationship of several years' duration. At the time of the accident, Ms Chadwick had recently discovered that she was 9 or 10 weeks pregnant.

On 10 March 2007, the couple and Ms Chadwick's 5 year old daughter set off from their home in the Adelaide Hills on for a weekend on the Yorke Peninsula. The following morning they met up with Mr Allen's friend, Martlew, and his two children, in Port Pirie. The group then travelled in Martlew's car to Kadina, Port Broughton and Wallaroo before arriving at Port Victoria late in the afternoon. The two men consistently consumed alcohol over the course of the day and until the early hours of the morning on 12 March 2007 when the collision occurred.

Between 1.30am and 2.00am, Ms Chadwick decided to go for a drive in order to purchase cigarettes. Mr Allen and Martlew accompanied her. The length of the journey and route taken were a matter of conjecture but it was found that Ms Chadwick drove around the town and its environs for approximately 10-15 minutes, during which time it was accepted that Mr Allen and Martlew were shouting a series of confusing directions at her.

At one point, Ms Chadwick pulled over to the side of the road and exited the vehicle in order to urinate. It was later ascertained that the car was stopped on the edge of the township, approximately 500m from the Port Victoria Hotel where they were staying with street lighting in the distance, to the north and south east, some 200m away in each direction. Notwithstanding these undisputed facts, Ms Chadwick gave evidence that she was "in the middle of nowhere", in complete darkness and disoriented as to her whereabouts.

When Ms Chadwick returned to the car, Mr Allen had assumed the driver's position and insisted that she get in. There was an argument between Ms Chadwick and appellant as to who should drive, with Mr Allen ultimately prevailing.

Mr Allen took off and drove into town aggressively and erratically. Ms Chadwick did not put on her seatbelt and it was contended that the gravitational forces generated by Mr Allen's manner of driving made it impossible for her to engage the seatbelt mechanism. A short time later he lost control negotiating a bend at high speed and collided with a tree. Ms Chadwick was ejected from the vehicle on impact, suffering spinal injuries resulting in complete L3 paraplegia.

Mr Allen's blood alcohol concentration at the time of the collision was estimated to be 0.229%. Ms Chadwick consumed minimal alcohol during the course of the day and night and returned a zero blood alcohol reading.


At first instance, the Trial Judge (Judge Tilmouth) found that:

  • Ms Chadwick ought to have been aware that Mr Allen's capacity to drive was impaired by alcohol, such that the presumption of contributory negligence applied and she was liable to have her damages reduced by 50% pursuant to Section 47 of the Act.
  • Ms Chadwick however satisfied the exception contained within 47(2)(b) of the Act in that she could not reasonably be expected to have avoided the risk of travelling with Mr Allen.
  • Ms Chadwick had no objective choice but to enter the car based on her belief that she was in a darkened area and her misapprehension of just how close she in fact was to the township. This was despite his findings that Ms Chadwick had "lied profusely in order to enhance her damages claim", the presence of streetlights and their operation on the night in question and the fact that Ms Chadwick was "within 600 m or less than 10 minutes walking distance from the motel unit".
  • As a matter of law, Ms Chadwick's failure to fasten her seatbelt might be excused on the basis that she was prevented complying with the statutory requirement to do so by the conduct of another, or in this case the erratic driving of the vehicle by Mr Allen.
  • However, the "act of a stranger" defence was not made out on the facts as the evidence indicated that there were at least two opportunities in which Ms Chadwick could have fastened her seatbelt. Accordingly, she was contributorily negligent and her damages were reduced by 25%.

Mr Allen appealed to the Full Court on the issue of intoxication and Ms Chadwick cross-appealed on the seatbelt reduction.

The majority (Gray and Nicholson JJ; Kourakis CJ dissenting) dismissed Ms Chadwick's appeal in relation to alcohol, observing that the question posed by Section 47(2)(b) was "whether the conduct of a plaintiff, in choosing to expose themselves to a risk of injury, which risk in fact eventuates, can be excused".

In doing so, Ms Chadwick's claimed disorientation and feelings of helplessness and panic were held to be "readily understandable" and rationalised her subsequent choice to expose herself to a risk of injury by riding with Mr Allen in lieu of walking the short distance back to the hotel. The majority observed that Ms Chadwick "is not to be judged by reference to the standard of a perfectly rational decision-maker".

The Full Court agreed with the Trial Judge that the mandatory reduction under Section 49 will not apply where the failure to wear a seatbelt occurred in circumstances of involuntariness or as a result of the unlawful act of another person. However, it unanimously set aside the finding of contribution on the basis that "Ms Chadwick's actions were a direct and natural response to Mr Allen's bad driving".

  • By grant of Special Leave, Mr Allen appealed to the High Court (French CJ, Kiefel, Bell, Keane and Gordon JJ) on the issue of contributory negligence which unanimously dismissed his appeal in relation to Section 47 and unanimously allowed his appeal in relation to Section 49, observing:
  • Section 47(2)(b) contemplates an objective evaluation of relative risk in a given situation by the exercise of reasonable powers of observation and appreciation of one's environment, as well as the exercise of a reasonable judgment of the relative risk of alternative responses to the environment as observed and understood.
  • The evaluation which Section 47(2)(b) involves makes no allowance for a claimant's subjective difficulties of cognition and decision-making, nor will confusion, panic or anxiety on the part of the claimant reduce what reasonableness requires.
  • On the evidence, it was not unreasonable for Ms Chadwick to have had no clear appreciation of her proximity to the township from the driver changeover point. Once accepted that Ms Chadwick did not know where she was, the availability of a relatively low risk alternative to travelling with Mr Allen was not readily apparent. Although a reasonable person may have taken the time to reflect upon their geographical location, they would not necessarily have appreciated that they were a relatively easy walk from the hotel and might still have formed the same imperfect understanding of their situation.
  • Ms Chadwick's age, pregnancy, the fact that she was on a dark and unfamiliar country road an uncertain distance from the township in the early hours of the morning could reasonably lead to an evaluation of a real risk of harm. The risk of riding with Mr Allen could reasonably be regarded as lessened to a relatively acceptable level due to the absence of other vehicular traffic on the roads at that time.
  • On a reasonable evaluation of these facts and the relative risks associated with them, Ms Chadwick could not reasonably be expected to have avoided the risk of travelling with Mr Allen.
  • The relevant question in relation to Section 49 was not whether Ms Chadwick's failure to fasten her seatbelt was an understandable, or even a reasonable response, to Mr Allen's driving, but whether she was prevented from doing so by him. The evidence did not support such a conclusion and there was no reason to interfere with the Trial Judge's findings of fact.


Although Ms Chadwick succeeded in avoiding the alcohol reduction on the particular facts of this case, the High Court's decision represents a clear rejection of the Full Court's approach which sought to assess the reasonableness of Ms Chadwick's decision-making by reference to her mental and emotional state.

The High Court confirmed that any subjective characteristics or idiosyncrasies which might diminish the injured person's capacity to make a reasonable assessment of the relative risks attendant upon a particular course of action, such as impetuosity, drunkenness, hysteria, mental illness or personality disorders, are immaterial to the evaluation which s47(2)(b) postulates.

The decision now brings South Australia into line with the objective approach to contributory negligence confirmed by Joslyn v Berryman (2003) 214 CLR 552 and will be of broader application in the Australian Capital Territory1, Queensland2, New South Wales3 and the Northern Territory4 and which have identical or similarly-worded counterpart provisions.

Until the advent of this decision, the "act of a stranger" doctrine was a peculiarly South Australian construct which had not been examined in any other Australian jurisdiction. Whilst it would appear that the defence may theoretically be available to rebut the presumption of contributory negligence where an injured person has failed to wear a seatbelt, in practical terms it will have very limited application confined to circumstances where such contravention is involuntary and compliance rendered entirely impossible by an extraneous and unforeseen event.


1 s96(2)(b) Civil Law Wrongs Act 2002 (ACT)
2 s48(3)(b) Civil Liability Act 2003 (QLD)
3 s138(2)(b) Motor Accidents Compensation Act 1999 (NSW)
4 s15 Personal Injuries (Liabilities and Damages) Act (NT)

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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