The Tort of Negligence.

The Scope of Negligence

Negligence is the cornerstone of modern tort law in Canada. It governs virtually every activity imaginable, from how motorists drive, to how professionals practice their crafts, to how property owners maintain their premises. Understanding negligence is essential whether you are seeking compensation for injuries suffered or defending against claims of wrongful conduct.

The scope of negligence law is remarkably broad. Courts have held that negligence standards apply to skiing accidents, racing car drivers, airline operations, jailers supervising inmates, nurses rushing to attend patients, and countless other scenarios. There is virtually no activity, new or old, rare or commonplace, dangerous or safe, that can escape review by negligence standards.

The Elements of Negligence

To establish a negligence claim in Ontario, a plaintiff must prove three essential elements:

1. Duty of Care: The defendant owed a legal duty to take reasonable care to avoid causing harm to the plaintiff. This is fundamentally a question of law.
2. Breach of the Standard of Care: The defendant failed to meet the required standard of care. Defining the legal standard is a question of law; whether the defendant met it is a question of fact.
3. Causation and Damages: The defendant's breach caused actual harm or loss to the plaintiff.

This treatise focuses on the second element, the standard of care and its breach, which is where most negligence disputes are won or lost. A leading example of the correct judicial approach to assessing standard of care is Hill v. Hamilton-Wentworth Regional Police Services Board.

Duty vs. Standard: The Critical Distinction

It is sometimes difficult to differentiate between duty of care and standard of care. In the famous case of Donoghue v. Stevenson, Lord Atkin established that defendants must "take reasonable care to avoid acts or omissions which you can reasonably foresee would be likely to injure your neighbour."

The distinction matters because actions are frequently dismissed on preliminary motions for failure to establish a duty of care. They are rarely dismissed on standard of care issues unless there are no facts that could plausibly support an allegation of unreasonable conduct. Duty is a gatekeeping question. Standard is an evaluative one.

The Objective Reasonable Person

The standard of care in negligence law is an objective standard, not a subjective one. The basic standard is that expected from a fictional "reasonable person," someone who would never take an unreasonable risk.

Courts have described the reasonable person in famously elaborate terms:

Although the courts pursue a common objective standard, subjective elements occasionally intrude. The standard varies depending on the class of defendant involved: children are judged differently than adults, professionals differently than laypeople, and those with physical disabilities are held to modified standards accounting for their limitations. See Chapter Five for the detailed modifications.

Fault Without Moral Blame

The words "fault" and "blame" are employed in negligence law, but without the moral opprobrium attached to these terms in criminal law. Negligence is about unreasonableness, not moral culpability. These terms have acquired special meanings that vary according to the context and the class of defendant involved.

This distinction is crucial: being found negligent does not mean you are a bad person or acted with evil intent. It simply means your conduct fell below what the law considers reasonable in the circumstances. This technical use of moral language is a frequent source of confusion for clients first encountering negligence claims.

Determining whether conduct is negligent requires assessing whether the defendant took an "unreasonable risk." Courts balance four factors in making this determination:

1. The probability that harm will occur
2. The magnitude of potential loss if harm occurs
3. The social utility of the defendant's conduct
4. The cost of taking precautions

The American jurist Judge Learned Hand articulated this balancing test mathematically: liability exists when the burden of adequate precautions (B) is less than the probability of harm (P) multiplied by the magnitude of loss (L). In other words: if B < P × L, the defendant is liable. Canadian courts do not apply this formula rigidly, but they engage in similar balancing exercises.

Factor 1: Probability of Harm

If there is only a slight risk that an accident will occur, courts may hold that running such a risk is not unreasonable. As the law recognizes, "people must guard against reasonable probabilities, but they are not bound to guard against fantastic possibilities." However, "probability" does not mean the accident must be more likely than not. There need only be a real or substantial risk of harm. One chance in 100 or even 1,000 may suffice.

The leading case is Bolton v. Stone, where a cricket batsman hit a ball over the fence into an adjoining highway, injuring the plaintiff. The cricket ground had been used for 90 years, and no one had ever been injured this way before. The House of Lords found the defendants not liable because "the chance of a person ever being struck even in a long period of years was very small."

Lord Reid established the test: whether "the risk of damage to a person on the road was so small that a reasonable man in the position of the appellants, considering the matter from the point of view of safety, would have thought it right to refrain from taking steps to prevent the danger."

Two contrasting Canadian cases illustrate the same principle applied to different facts:

• Shilson v. Northern Ontario Light and Power Co.: A 12-year-old boy was injured by an electric wire while crossing a ravine on a 12-inch pipe. The court held it was so improbable that "even a venturesome and mischievous boy" would attempt to cross a ravine 17 to 19 feet deep and 300 feet wide on a narrow pipe that the defendant owed no duty to take precautions.
• Gloster v. Toronto Electric Light Co.: An eight-and-a-half-year-old child touched an uninsulated wire 14 to 20 inches from a bridge used by many people daily. Recovery was permitted because the probability of someone touching this wire was significant enough to call for safety measures.

Weather and Extraordinary Conditions. Steps must be taken to prevent damage from normal weather vicissitudes, but not from abnormally severe conditions that rarely occur. Courts have declined to impose liability for loss caused by unprecedented frosts, "extraordinary falls of rain," "cyclones, tornados, hurricanes" of "unique, severe and exceptional kind," or fires ignited in ways no one had experienced before. However, liability has been imposed for structures blown down by winds characterized as "violent, but not of unusual violence." The distinction lies in whether the weather event was within the realm of normal expectation or truly extraordinary.

Sensitivity and Special Vulnerabilities. Extraordinarily sensitive individuals are generally denied special protection because they are seldom encountered. In Elverson v. Doctors Hospital, a hospital was relieved of liability when a plaintiff aggravated a pre-existing back condition while helping a nurse elevate a patient's bed. The court held this was a "common, everyday occurrence, completely devoid of any inherent danger" and that "the particular susceptibility of the plaintiff was beyond any range of normal expectancy or of reasonable foresight." Similarly, in Munshaw Colour Service Ltd. v. Vancouver (City), when sediment in city water damaged a film company's specialized filtering equipment, the court held that municipalities cannot be expected to consider "consumers of peculiar sensitivity."

Factor 2: Magnitude of Potential Loss

When the potential loss is great, even creating a slight risk may give rise to liability. As Professor Fleming wrote: "Not only the greater risk of injury, but also the risk of greater injury is a relative and relevant factor."

Even if lightning is highly unlikely to strike at a given place and time, one must take precautions against this "extreme hazard" because the precautions must be "commensurate with the danger." If the threatened harm in Bolton v. Stone had been "a bullet in the heart or a nuclear explosion, rather than just a bump on the head," the defendant might have been liable despite the low probability.

In Paris v. Stepney Borough Council, a one-eyed man was blinded when a metal chip flew into his good eye while working. The employer had not provided goggles, though the usual trade practice was not to supply them for this work, at least not for workers with sight in both eyes. The House of Lords concluded in a 3-2 decision that the gravity of the harm likely to be caused influenced what a reasonable employer would do. Even though no duty was owed to supply goggles to a two-eyed employee, the duty of care to a one-eyed employee required providing goggles. The potential loss, total blindness rather than loss of one eye, made the difference.

Factor 3: Social Utility of the Conduct

Even with substantial risk and potentially severe damage, defendants may be excused if their activities have high social utility. Where the objectives served are laudable enough, risks may be taken.

The leading case is Priestman v. Colangelo and Smythson, involving a 17-year-old car thief fleeing from police along Toronto streets. When the youth refused to stop after warning shots, an officer aimed at a tire but accidentally shot the driver in the neck due to a bump in the road. The car went out of control and fatally injured two young women waiting for a bus.

The Supreme Court of Canada, in a 3-2 decision, dismissed the families' claims. The majority held that the hazard created was not too great given "the social value of capturing a criminal whose actions constitute a menace to other members of the public." The police could take certain reasonable risks in apprehending fleeing criminals, though they could not do anything that came to mind. It is likely the dissenting views would prevail today, as society has come to recognize much safer methods of arresting car thieves than high-speed chases or gunfire.

Courts have recognized that certain activities, while risky, serve such important social purposes that they warrant acceptance of some danger: emergency medical procedures where speed is essential, fire rescue operations, essential infrastructure work during emergencies, and military operations and training. The key is whether the social benefit justifies the risk created. Activities must still be conducted with reasonable care given the circumstances, but the threshold for what constitutes "reasonable" adjusts based on social utility.

Factor 4: Cost of Precautions

The burden or cost of taking adequate precautions is a relevant factor in determining negligence. If precautions would be disproportionately expensive or impractical compared to the risk, courts may excuse their absence.

However, this factor has limits. Where an activity creates substantial risks, it should either be conducted with proper precautions or not conducted at all. As Lord Reid noted in Bolton v. Stone, "if cricket cannot be played on a ground creating a substantial risk, then it should not be played there at all." The activity's social utility does not justify continuing to engage in it if the risks cannot be adequately managed.

This principle extends across industries. Construction companies cannot plead poverty as an excuse for failing to provide basic safety equipment. Manufacturers cannot avoid recalls of dangerous products based on cost considerations alone. Property owners cannot neglect essential maintenance simply because repairs are expensive. Courts will consider whether the precautions demanded are reasonable given the defendant's circumstances, but cost cannot trump clear and substantial dangers.

Balancing all four factors. These four factors do not operate in isolation. Courts engage in a holistic balancing exercise, weighing all considerations together. A low probability of harm might excuse inaction if the potential loss is also minor and precautions costly. But high potential severity may demand precautions even if the probability is low, especially if precautions are inexpensive or straightforward. The analysis is inherently flexible, designed to adapt to the infinite variety of human activities and potential harms.

Knowledge, Intelligence & Skills

The reasonable person is assumed to possess normal intelligence and the knowledge that an ordinary person would have in the circumstances. This includes general knowledge and common sense that adults typically possess, awareness of obvious dangers and common risks, knowledge of basic physical laws and cause-and-effect relationships, and information that would be readily apparent through ordinary observation. However, the reasonable person is not expected to have specialized knowledge unless the defendant actually possesses such knowledge or the circumstances require it.

The duty to expand knowledge by consulting. While the reasonable person is not expected to possess specialized knowledge, there are circumstances where a reasonable person would recognize their limitations and seek expert advice. A property owner undertaking complex structural work might be expected to consult an engineer. A business owner implementing new safety procedures might need to consult safety professionals. The duty to consult arises when the risks are significant and apparent, the activity is beyond ordinary competence, expert knowledge is readily available, and a reasonable person would recognize the need for specialized input.

Physical disabilities. The law makes accommodations for physical disabilities. A person with impaired vision, hearing, or mobility is held to the standard of a reasonable person with similar disabilities, not to the standard of a fully able-bodied person. This modification recognizes that it would be unfair and impractical to hold people to standards they physically cannot meet. However, this accommodation has limits: people with disabilities must still take reasonable precautions given their limitations, they may have a duty to avoid activities their disability makes unreasonably dangerous, and they cannot claim disability as an excuse if they chose to engage in activities beyond their capabilities.

Superior knowledge and skills. Those who possess superior knowledge, skills, or training are held to a higher standard reflecting those advantages. A surgeon is held to the standard of a reasonable surgeon, not simply a reasonable person. An experienced driver is held to a higher standard than a newly licensed one. This principle ensures that defendants cannot avoid liability by claiming ignorance of matters they actually know or by failing to use skills they actually possess.

Control of Children

Parents and guardians have a duty to exercise reasonable care in supervising children under their control. The standard is not one of perfect supervision (children will inevitably find ways to get into mischief) but rather reasonable oversight given the child's age and maturity, the child's known propensities and character, the nature of the setting or environment, and the foreseeable risks present.

The duty of supervision exists not only to protect the children themselves but also to protect third parties from harm the children might cause. A parent whose child habitually plays with matches may have a duty to take extra precautions to prevent the child from starting fires, for example, that would not apply to a parent whose children display no such tendencies.

Youth & Children

Children of tender age. Very young children, generally those under seven years old, are presumed incapable of negligence. This reflects the reality that children at this developmental stage cannot be expected to appreciate risks or make mature judgments about their conduct. This presumption is rebuttable in some jurisdictions, meaning that in extraordinary circumstances, evidence might establish that even a very young child could understand the risks involved in particular conduct. Such cases are rare.

Children beyond tender age. For children old enough to potentially be held negligent but not yet adults, courts apply a modified standard: that of a reasonable child of similar age, intelligence, and experience. Unlike the purely objective adult standard, the child standard considers the individual child's actual age, intelligence, and experience. The older the child, the closer the standard approaches that of an adult. What is expected of a 10-year-old riding a bicycle differs from what is expected of that same child operating a boat.

Courts recognize that children may not appreciate risks that adults readily recognize, have less developed judgment and impulse control, are more prone to distraction and inattention, may overestimate their own abilities, and are less likely to consider consequences before acting.

The adult activity exception. An important exception exists when children engage in "adult activities." When a minor operates motor vehicles, boats, or other potentially dangerous equipment typically used by adults, courts generally hold the child to an adult standard of care. The rationale is straightforward: other users of the roadways or waterways have no way of knowing whether the driver or operator is a child or an adult, and they are entitled to expect adult levels of competence from those operating these vehicles. To hold child operators to a lesser standard would create unacceptable risks for others. This exception typically applies to operating automobiles, trucks, and motorcycles; operating boats and watercraft; operating farm equipment and heavy machinery; handling firearms; and other activities carrying serious risks where age-based standards would endanger others.

Mental Illness & Cognitive Impairment

The law's treatment of mental illness in negligence claims is more nuanced and contested than its treatment of children. The general rule, though subject to significant criticism and some exceptions, is that mental illness or cognitive impairment does not excuse conduct that would otherwise be negligent.

The traditional rule. Courts have traditionally held that defendants with mental illness are judged by the same reasonable person standard as everyone else. The rationale includes the difficulty of assessing mental conditions that vary widely in nature and severity, concerns that defendants might fake or exaggerate mental illness to avoid liability, the argument that injured parties should not bear losses simply because the person who caused them had a mental illness, and the incentive structure that caregivers and family members may be more diligent in supervision if liability is not excused by mental illness.

Criticisms and exceptions. This traditional rule has been heavily criticized as unduly harsh and inconsistent with accommodations made for children and physical disabilities. Some argue it fails to recognize that mental illness can be as limiting as physical disability. Courts have carved out limited exceptions, particularly where the mental condition arose suddenly and without warning, the defendant had no prior knowledge of the condition, the defendant could not have reasonably foreseen the episode, or the defendant took reasonable precautions given their knowledge of the condition.

Professional Negligence

Professionals, including lawyers, doctors, accountants, engineers, architects, and others, are held to the standard of a reasonably competent practitioner in their field, not merely to the standard of a reasonable layperson.

Several principles structure professional negligence claims. Reasonable competence, not perfection. Professionals are not guarantors of results. They are required to exercise the skill and care that would be exercised by a reasonably competent professional in similar circumstances. Mere errors in judgment or unsuccessful outcomes do not constitute negligence if the professional acted competently.

Specialist standards. Specialists are held to the standard of reasonable specialists in their specific field. A cardiologist is held to the standard of a reasonable cardiologist, not merely that of a general practitioner. A patent lawyer is held to the standard of a reasonable patent lawyer, not merely that of a general practitioner.

Keeping reasonably current. Professionals must keep reasonably abreast of developments in their fields. They need not know every new study or technique, but they must maintain reasonable competence through continuing education and awareness of significant developments.

Honest errors of judgment. Where professional practice involves the exercise of judgment, professionals are not liable for honest errors of judgment, provided they acted with reasonable care. Multiple approaches may be acceptable, and choosing one approach over another does not constitute negligence simply because a different approach might have worked better.

Informed consent and communication. Many professional negligence cases involve failures of communication. Doctors must obtain informed consent. Lawyers must properly explain risks and options to clients. Accountants must ensure clients understand their advice. The duty of care encompasses both technical competence and adequate communication.

Establishing professional negligence. Proving professional negligence typically requires expert testimony. Because the standard is that of a reasonable professional, not a layperson, plaintiffs must usually present evidence from other professionals explaining what a reasonably competent professional would have done in the circumstances, how the defendant's conduct fell below that standard, and how that deviation caused the plaintiff's injuries. Exceptions exist where the negligence is so obvious that laypeople can readily understand it, for instance, operating on the wrong body part or missing an obvious statutory deadline.

Custom & Industry Standards

The relationship between custom and negligence is complex. Prevailing industry practices are relevant evidence in determining the standard of care, but they are not conclusive. Courts maintain the authority to find conduct negligent even if it conforms to industry custom, and conversely, to excuse conduct that deviates from custom.

Compliance with custom as evidence of reasonable care. Evidence that a defendant complied with industry custom or accepted practices is admissible and often persuasive. If most people engaged in similar activities follow certain procedures, this suggests those procedures represent reasonable care. Courts will consider how widespread the practice is in the industry, how long the practice has been followed, whether the practice is codified in industry standards or regulations, whether the practice is followed by reputable practitioners, and whether there is consensus in the industry about appropriate methods. However, custom is not a complete defence. The question remains whether the custom itself represents reasonable care.

Deviation from custom. Evidence that a defendant deviated from industry custom is likewise admissible and relevant. If everyone else in the industry uses safety equipment that the defendant omitted, this is probative of negligence. However, mere deviation from custom does not automatically establish negligence. The deviation must be unreasonable. Courts recognize that progress requires innovation and deviation from established practices, custom may lag behind available safety improvements, individual circumstances may justify different approaches, and custom may be based on cost-cutting rather than safety considerations.

When custom itself is negligent. Perhaps most importantly, courts have held that compliance with custom does not necessarily demonstrate reasonable care. Industry-wide practices can themselves be negligent.

Courts will scrutinize custom when the custom creates obvious and substantial risks, better safety measures are available and feasible, the custom appears driven by cost savings rather than reasonable safety considerations, the custom has not kept pace with technological or safety advances, or the custom serves the industry's interests at the expense of public safety. This principle prevents industries from insulating themselves from liability by collectively adopting unsafe but profitable practices.

Statutory Violations & the Standard of Care

The relationship between statutory violations and negligence liability has been a source of confusion and controversy. When a defendant violates a safety statute or regulation, does this automatically establish negligence? The answer in Canada was definitively clarified by the Supreme Court in Canada v. Saskatchewan Wheat Pool.

The law before Saskatchewan Wheat Pool. Prior to 1983, Canadian courts applied an inconsistent and problematic approach to statutory violations. Courts claimed to search for "legislative intent" to determine whether a statute's violation would give rise to civil liability. The problems with this approach were manifold. Most statutes say nothing about civil liability; legislators simply prohibit conduct and specify penalties. True legislative intent was rarely apparent in the statutory text. The imposition of civil liability became "capricious" and "impossible to predict on any rational basis." Lord Denning described this area of law as a "guesswork puzzle" where one "might as well toss a coin to decide it."

The Saskatchewan Wheat Pool decision. In a learned, bold, and unanimous decision, the Supreme Court of Canada fundamentally reformed Canadian law. The facts: the plaintiff incurred expenses after receiving wheat infested with rusty grain beetle larvae from the defendant. The defendant violated the Canada Grain Act, which forbade discharging infested grain from elevators. However, according to all the evidence, the defendant's conduct was completely free of any negligence. The infestation was essentially unavoidable despite reasonable care.

Justice Dickson made several decisive rulings. Legislative intent theory rejected. The Court abandoned the "fictitious hunt for legislative intent," calling it "capricious and arbitrary" and a "bare-faced fiction at odds with accepted canons of statutory interpretation." Instead, the Court recognized that whether to rely on statutory violations in tort cases is "a question to be decided by the court" based on "considerations of policy and convenience."

Statutory breach located within negligence law. The Court decisively rejected the notion of a separate "tort of breach of statutory duty." Instead, statutory violations were brought squarely within negligence law. Civil liability for statutory breach is "a creature of the court," not of the legislature.

Breach as evidence, not proof. The Court adopted the principle that "proof of statutory breach, causative of damages, may be evidence of negligence." This means judges and juries may consider statutory violations in their deliberations but are not controlled by this evidence. They can find negligence without a statutory violation, or find no negligence despite a violation. Defendants who violate statutes are not required to prove they exercised reasonable care. If defendants remain silent, they may still be exonerated, though silence might be risky. This approach rejects both the American view that statutory violations constitute "negligence per se" (automatic strict liability) and the former Canadian view that violations provide "prima facie evidence" of negligence (shifting burden of proof).

Justice Dickson offered several reasons for affording less weight to statutory violations. Intellectual honesty (it avoids fictitious searches for non-existent legislative intent). Flexibility (it prevents inflexible application of criminal standards to civil cases). Legislative activity (modern legislatures actively create compensation schemes when they want them; silence suggests no such intent). Alternative compensation (non-tort compensation schemes have reduced the need for tort recovery). Fault principles (tort law increasingly emphasizes fault; there is "little defensible policy for holding a defendant who breached a statutory duty unwittingly to be negligent and obligated to pay even though not at fault"). Proportionality ("inconsequential violations should not subject the violator to any civil liability" but should be left to criminal courts). Natural justice (the trend is to "ameliorate the rigors of absolute rules and absolute duty as contrary to natural justice").

Industrial safety legislation exception. The Court recognized that "industrial legislation historically has enjoyed special consideration," sometimes leading to absolute liability regardless of fault. This exception was permitted to continue, though its practical utility is limited in Canada given extensive workers' compensation legislation.

Application in practice. Under the Saskatchewan Wheat Pool approach, statutory violations function as one piece of evidence among many. Courts will consider whether the statute represents a legislative judgment about reasonable care in specific circumstances, whether the statutory standard is appropriate to adopt as the civil standard, whether the violation was inadvertent or egregious, whether the violation actually contributed to the harm, and all other circumstances bearing on whether the conduct was reasonable. The result is a more flexible, honest, and just approach that empowers judges and juries to make reasonable assessments rather than being bound by rigid rules disconnected from actual fault.