There are four defences to an action in negligence: contributory negligence, voluntary assumption of risk (volenti non fit injuria), illegality (ex turpi causa non oritur actio), and inevitable accident. Contributory negligence is a partial defence that leads to a reduction in the damages payable by the defendant. Voluntary assumption of risk, illegality, and inevitable accident are complete defences to the plaintiff’s action. The evolution of these defences mirrors the evolution of negligence from a system emphasizing the concept of shifting loss between individuals on the basis of clearly established moral culpability to one that is significantly influenced by the loss-spreading power of liability insurance systems and compensatory concerns. In a loss-shifting system of corrective justice, defences are integral to achieve a fair result between the litigants. When compensatory and loss distribution goals predominate, defences tend to be perceived as impediments to addressing the compensatory needs of plaintiffs. Consequently, there has been a progressive restriction in the definition, scope, and application of the defences
in negligence law. While contributory negligence continues to show some vitality, voluntary assumption of risk, illegality, and inevitable accident have been so successfully marginalized as to be of little practical consequence.
Contributory negligence is the failure of the plaintiff to take reasonable care for her own safety which contributes to the accident or her loss. Under the old common law, contributory negligence was a complete de-fence to an action in negligence. The plaintiff was viewed as undeserving, a wrongdoer who did not warrant protection from the negligence of another. The allocation of the loss to the negligent plaintiff was also consistent with the tendency of the old common law to seek out a single cause of an accident. However, the injustice of placing all the loss on the plaintiff soon became apparent, particularly in cases where the plain-tiff’s negligence was comparatively trivial and preceded the defendant’s negligence. The courts responded to these situations by developing the rule of last clear chance, which held that, in cases where the defendant had the last clear opportunity to avoid the accident, the defendant was the sole cause of the accident and fully responsible for the plaintiff’s losses. This provided the courts with some discretion to allocate 100 percent of the loss either to the plaintiff or to the defendant as justice demanded. Yet the common law proved incapable of developing the intuitively correct rule of splitting the loss between the two wrongdoers.
Eventually, apportionment of the loss between the parties was introduced in all provinces by legislation.214The legislation is not uniform and each Act must be carefully analysed to determine its scope and application and the extent to which remnants of the old common law doctrines such as the rule of last clear chance survive. There is, however, a great deal of consistency in the way the legislation deals with the issue of contributory negligence in the typical negligence ac-
tion. If the negligence of the plaintiff contributed to her loss, the court must determine the degree to which the plaintiff is responsible for that loss and reduce the damages accordingly.215If a court is not able to determine the respective degrees of fault of the parties, they are deemed to be equally at fault and the defendant is liable for 50 percent of the damages. In this way the legislation provides the courts with a flexible loss allocation mechanism and avoids the all-or-nothing approach of the common law.216Contributory negligence can arise in three ways.217First, the plaintiff’s negligence may be a cause of the accident. In Cork v. Kirby Mac-Lean Ltd.,218a worker suffered an epileptic fit and fell from an unsafe scaffolding on which he was standing. He had imprudently failed to tell his employer that he suffered from epilepsy. The Court held that, if he had told his employer of his illness, he would not have been assigned to work on the scaffold and the accident would probably not have occurred.219The loss was allocated equally between the defendant, whose failure to provide a safe scaffolding was also a cause of the loss, and the plaintiff. Second, contributory negligence may arise where the plaintiff’s negligence is not a cause of the accident but he has put himself in a position of foreseeable harm from the defendant’s negligence. A passenger who chooses to get into a car with a driver whom she knows to be intoxicated will be found to be contributorily negligent. Third, a plaintiff may fail to take protective measures in the face of foreseeable danger such as a failure to use an available seat belt in an automobile
or aircraft. If the plaintiff’s loss would have been less severe if the precautions had been taken, damages will be reduced for contributory negligence.
Contributory negligence is determined by applying the objective standard of the reasonably prudent person. Consideration is given to the same factors as are influential in deciding a defendant’s negligence. The foreseeability of harm, the likelihood of damage, the seriousness of the threatened damage, the cost of precautionary measures, the exigencies of emergency situations, and the utility of the plaintiff’s conduct are all taken into account. The utility of the plaintiff’s conduct is particularly influential in respect of police officers and rescuers where the task undertaken demands a selfless disregard for one’s own safety. Courts are reluctant to reduce damages in such cases.
The plaintiff’s negligence must contribute to the harm, but the assessment of contributory negligence is not made on the degree to which the conduct of each party caused the harm. It is made on the basis of the comparative blameworthiness of the conduct of the parties. Consequently, proof that a plaintiff would have suffered no injuries in a motor vehicle accident if she had been using her seatbelt does not warrant a large reduction for contributory negligence. The character of the comparative wrongdoing is different. The defendant has breached his duty of care to users of the highway and has caused the accident. The plaintiff has failed to protect herself from the consequences of the defendant’s wrongdoing. The defendant, consequently, must bear the greater share of the loss.220Overall, the apportionment process in cases of contributory negligence tends to be conventional, arbitrary, and lenient. It is conventional in the sense that in many cases courts either reduce damages by 20 to 30 percent or they utilize the option of splitting the loss either because of a rough equality of fault between the parties or because it is not possible to allocate the respective degrees of fault of the parties. This permits contributory negligence to play some role in accident prevention without unduly affecting the compensatory functions of negligence law. It is arbitrary in the sense that, although courts are required to make an assessment of blameworthiness, they are often not particularly sensitive to degrees of culpability. For example, the same 25 percent reduction in damages has been made where a passenger failed to wear her seat belt221and where a grossly intoxicated person participated in
a tube-racing competition down a mogulled ski hill after he had been warned of the extreme danger of doing so.222It is lenient in respect of both the degree of reduction in the damages (not often in excess of 50 percent and often less than 30 percent), and the manner in which the standard of care is applied. This leniency is largely due to the patterns of insurance. Judges are acutely aware of the harsh consequences of a finding of contributory negligence, particularly in personal injury litigation. Plaintiffs who suffer personal injury often do not carry first-party disability insurance. A 25 percent reduction of a large award will, therefore, result in a harsh penalty and significant undercompensation. Defendants, on the other hand, are normally covered by liability insurance and are largely immune from personal hardship when liability is imposed. Courts are therefore more indulgent of plaintiffs than they are of defendants. This attitude is even evidenced in some cases of damage to property where first-party insurance is more common. The New Brunswick Court of Appeal decision in...