9.2 Negligence Elements, Causation & Tort Remedies/Damages

Negligence is the workhorse tort of Ontario civil litigation, underlying most motor vehicle, occupier, professional, and product claims that paralegals handle in Small Claims Court. The P1 exam expects candidates to walk through the four elements of a negligence claim in order, identify the leading defences, and match remedies to fact patterns.

The Four Elements of Negligence

A plaintiff must prove, on a balance of probabilities:

1. Duty of care — a legal obligation to avoid causing reasonably foreseeable harm to the plaintiff.
2. Standard of care (breach) — the defendant fell below what a reasonable person would have done in the circumstances.
3. Causation — the breach actually caused the plaintiff's loss.
4. Remoteness and damages — the loss was not too remote, and it can be proven.

Duty of Care

Canadian courts use the Anns/Cooper test, from Cooper v. Hobart, to decide whether a duty of care exists in a novel situation:

• Stage 1: Was the harm reasonably foreseeable, and was there sufficient proximity between the parties? This traces back to Lord Atkin's "neighbour principle" in Donoghue v. Stevenson: a person must take reasonable care to avoid acts or omissions that could reasonably be foreseen to injure their neighbour.
• Stage 2: Are there residual policy reasons to negate or limit the duty, such as indeterminate liability or a conflicting statutory duty?

Many duty relationships are already well established by prior cases — driver and pedestrian, doctor and patient, occupier and visitor — and do not require a fresh Anns/Cooper analysis in every file.

Standard of Care

The standard is that of the reasonable person in the defendant's position, not perfection. Courts weigh the probability and severity of harm, the cost of precautions, and the utility of the defendant's conduct. Professionals, including paralegals, are held to the standard of a reasonably competent member of their own profession rather than an ordinary person, following ter Neuzen v. Korn. Children are generally held to the standard of a reasonable child of similar age, intelligence, and experience, unless they are engaged in an inherently adult activity such as driving a motor vehicle.

Causation

Causation is tested with the "but for" test: but for the defendant's negligence, would the plaintiff's harm have occurred? The Supreme Court of Canada, in Clements v. Clements, confirmed "but for" as the default test, reserving the more relaxed material contribution to risk test for rare cases involving multiple negligent defendants where it is impossible to know which one factually caused the harm, and where it would be unfair to the plaintiff to deny recovery altogether.

Remoteness

Even where causation is proven, a defendant is only liable for reasonably foreseeable types of damage, under the Wagon Mound principle, not every consequence that flows, however unlikely, from the breach. The "thin skull rule" is an important exception: a defendant must take the plaintiff as found and is liable for the full extent of an unusually severe injury, even if the extent was unforeseeable, provided the general type of injury was itself foreseeable.

Defences to Negligence

Contributory negligence is the defence most often tested. Ontario's Negligence Act allows a court to apportion fault between a plaintiff and one or more defendants by percentage, reducing the plaintiff's recovery accordingly. A plaintiff found 20% at fault for failing to wear a seatbelt, for example, has total damages reduced by 20%, regardless of how the accident itself was caused.

Types of Damages

A plaintiff also has a duty to mitigate — to take reasonable steps to minimize the loss — and cannot recover for losses that reasonable mitigation would have avoided.

Product Liability

Canada does not have a United States-style regime of strict product liability; product claims are generally pursued in negligence, alongside any available contract claim for breach of the Sale of Goods Act implied conditions, or a claim under the Consumer Protection Act, 2002. Manufacturers owe two related duties:

• A duty to design and manufacture products that are reasonably safe for their intended use.
• A duty to warn of known dangers, including risks discovered only after the product has already been sold — a continuing obligation, not a one-time disclosure.

The learned intermediary rule, discussed by the Supreme Court in Hollis v. Dow Corning Corp., allows a manufacturer of a product supplied through a learned intermediary, such as a physician prescribing a medical implant, to satisfy the duty to warn by adequately informing that intermediary in some circumstances. In Hollis, however, the Court held the manufacturer remained liable because the warning actually given to the intermediary was inadequate.

Occupiers' Liability

Ontario's Occupiers' Liability Act replaces the old common law categories of invitee, licensee, and trespasser with a single statutory duty: occupiers must take reasonable care in all the circumstances to see that persons on the premises, and their property, are reasonably safe. This unified standard is central to the slip-and-fall claims that make up a large share of paralegal-handled Small Claims files, and paralegals must be able to identify who qualifies as an "occupier" — which can include a tenant, landlord, or contractor in control of the premises, not only the registered owner.