NPPE Tort Law and Negligence 2 — Questions and Answers

Question 1: Which of the following best states the elements that a plaintiff must prove in a negligence action against a professional engineer in Canada?

Duty of care, breach, causation, and damages (Correct answer)
Intention to harm, breach, and damages
Contractual obligation, breach, and loss
Foreseeability and proximity only

Correct answer: Duty of care, breach, causation, and damages

A successful negligence claim requires proof of all four elements: (1) the defendant owed a duty of care to the plaintiff; (2) the defendant breached that duty; (3) the breach caused the plaintiff's harm (causation); and (4) the plaintiff suffered actual damage.

The four elements of negligence in Canadian law are: (1) Duty of care — the defendant owed a legal obligation to take care toward the plaintiff (established by the Anns/Cooper test for novel duties or by recognised established categories); (2) Breach — the defendant's conduct fell below the standard of care (the reasonable professional test); (3) Causation — the breach caused the plaintiff's loss (but for test or material contribution); and (4) Damages — the plaintiff suffered legally cognisable harm. All four elements must be proved on a balance of probabilities. If any element fails, the negligence claim fails. Professional engineers who understand these elements can better recognise and manage their legal exposure.

Question 2: What is 'res ipsa loquitur' and in what type of engineering negligence case might it apply?

A Latin term meaning 'let the engineer speak' — requires the engineer to testify
The thing speaks for itself — allows an inference of negligence from the very occurrence of an accident that would not normally happen without negligence (Correct answer)
A rule excluding hearsay evidence in engineering disputes
A standard for calculating damages in complex cases

Correct answer: The thing speaks for itself — allows an inference of negligence from the very occurrence of an accident that would not normally happen without negligence

Res ipsa loquitur allows a court to infer negligence from the occurrence of an accident that, in ordinary circumstances, would not occur without negligence — shifting the evidentiary burden to the defendant to provide an explanation.

Res ipsa loquitur ('the thing speaks for itself') is a principle that allows an inference of negligence where: (1) the event would not ordinarily occur without negligence; (2) the instrumentality causing the harm was under the exclusive control of the defendant; and (3) the plaintiff did not contribute to the accident. In engineering cases, it might apply where, for example, a newly constructed bridge collapses shortly after opening — the collapse itself suggests negligence without the plaintiff needing to identify the specific defect. The defendant can rebut the inference by providing a plausible non-negligent explanation. Canadian courts apply this as a rule of evidence, not a separate cause of action.

Question 3: What is the 'thin skull rule' (or 'eggshell skull rule') in Canadian tort law, and how does it affect professional liability claims?

Damages are limited to what a person of average constitution would have suffered
A defendant must take the plaintiff as they find them — if the plaintiff has a pre-existing vulnerability, the defendant is liable for the full extent of the harm even if it is greater than expected (Correct answer)
The rule that only foreseeable types of harm are compensable
A rule limiting damages in personal injury cases to $500,000

Correct answer: A defendant must take the plaintiff as they find them — if the plaintiff has a pre-existing vulnerability, the defendant is liable for the full extent of the harm even if it is greater than expected

The thin skull rule requires a defendant to take the plaintiff as they find them. If the plaintiff's pre-existing condition makes them more vulnerable to harm, the defendant is liable for the full extent of the damage, even if it is disproportionate to what a normal person would have suffered.

The thin skull rule (eggshell skull rule) is established Canadian law (Athey v Leonati [1996] 3 SCR 458). It provides that where a negligent act causes harm, the defendant is responsible for the full extent of the plaintiff's injuries, even if the plaintiff had a pre-existing vulnerability that made them more susceptible to harm. For engineers: if negligent advice damages a financially fragile client more severely than a healthy client would have been affected, the engineer's liability is not limited to the harm a financially robust client would have suffered. Note the distinction from the 'crumbling skull' rule: a defendant is not liable for the natural progression of a pre-existing condition unrelated to the negligent act.

Question 4: Under Canadian law, which type of economic loss arising from professional negligence typically faces the highest legal hurdles to recovery?

Economic loss consequential upon physical damage to the plaintiff's own property
Pure economic loss (financial loss unaccompanied by physical injury or property damage) (Correct answer)
Damages for pain and suffering in personal injury cases
Loss of profits on a cancelled contract

Correct answer: Pure economic loss (financial loss unaccompanied by physical injury or property damage)

Pure economic loss — financial harm not consequential on physical injury or property damage — is traditionally the most difficult category to recover in negligence, requiring satisfaction of additional legal requirements beyond the standard negligence elements.

Canadian tort law restricts recovery of pure economic loss (PEL) to categories of recognised relationships to prevent indeterminate liability (the 'floodgates' concern). The Supreme Court of Canada in Cooper v Hobart and subsequent cases has recognised several categories of PEL recovery: negligent misstatement causing economic loss (Hedley Byrne), negligent performance of a service, negligent supply of defective products or structures, relational economic loss (rare), and public authority liability. Outside these categories, PEL claims face significant hurdles. By contrast, economic loss consequential on physical damage to the plaintiff's property is recoverable under standard negligence principles.

Question 5: Which defence in tort law allows a defendant to argue that the plaintiff voluntarily accepted the risk of injury?

Contributory negligence
Volenti non fit injuria (Correct answer)
Ex turpi causa
Necessity

Correct answer: Volenti non fit injuria

Volenti non fit injuria ('to a willing person, injury is not done') is a complete defence that bars recovery if the plaintiff fully and voluntarily accepted the legal risk of the harm that occurred.

Volenti non fit injuria is a complete defence in Canadian tort law — if successful, it bars the plaintiff's recovery entirely. It requires: (1) the plaintiff had knowledge of the specific risk of harm; (2) the plaintiff voluntarily agreed to accept the legal risk (not just the physical risk). The defence is narrow: a mere warning notice or participation in an inherently risky activity does not automatically establish volenti — the plaintiff must be shown to have agreed to waive their legal rights. In professional liability contexts, a client who is fully informed of the risks associated with a non-standard engineering approach and consents to proceed may be found to have accepted the risk, though this is rarely a complete bar in Canadian courts.

Question 6: In the context of professional engineering liability, what is the significance of 'novus actus interveniens'?

A rule requiring engineers to novate their contracts in writing
An intervening act that breaks the chain of causation between the engineer's negligence and the plaintiff's harm, potentially relieving the engineer of liability for subsequent damage (Correct answer)
A rule requiring fresh consideration for contract modifications
A doctrine requiring engineers to disclose conflicts of interest

Correct answer: An intervening act that breaks the chain of causation between the engineer's negligence and the plaintiff's harm, potentially relieving the engineer of liability for subsequent damage

Novus actus interveniens is an intervening act that breaks the chain of causation. If a third party's independent and unforeseeable act intervenes between the engineer's negligence and the plaintiff's harm, the engineer may not be liable for the damage caused by the intervening act.

The causal chain between an engineer's negligence and the plaintiff's harm can be broken by a 'novus actus interveniens' — a new intervening act. For the intervening act to break the chain, it must be: (1) independent of the original negligence, (2) unforeseeable, and (3) the immediate cause of the harm. If the intervening act was foreseeable as a likely consequence of the original negligence, it will not break the chain. For example: if an engineer negligently designs an unstable structure and a third party then vandalises the already unstable element causing collapse, the chain may be broken if the vandalism was truly unforeseeable. Courts analyse the foreseeability of the intervening act to determine whether it breaks causation.

NPPE Tort Law and Negligence 2

Which of the following best states the elements that a plaintiff must prove in a negligence action against a professional engineer in Canada?