Supreme Court of Canada Clarifies Negligence Test – Clements v. Clements


In personal injury cases, the most recent word from our top court regarding the test for negligence (and thus liability for accidents) was Resurfice Corp. v. Hanke, 2007 SCC 7. Although Resurfice was quite comprehensive, it left open some questions as to the exact nature of the test to be applied, which the court has addressed in Clements v. Clements, 2012 SCC 32, which was on appeal from the British Columbia Court of Appeal.

This case involved a Motorcycle passenger injured in crash.  The motorcycle was overloaded by 100 pounds and had a nail in the tire which flew out when the bike was driven 120kph (in a 100 kph zone) causing the tire to deflate, the bike to wobble, and a crash to ensue.  Tragically, this caused a brain injury to the driver’s wife – the passenger.  Clearly, this sequence of events makes it difficult to impossible to point to the single or primary cause of the accident.  Where there are multiple causes of an accident, the law faces the challenge of sorting out who should be responsible for the damage, and where multiple parties are responsible, to what percentage they should pay damages.

In general, negligence is determined on the basis of the ‘but for’ test – the plaintiff must show on a balance of probabilities that “but for” the defendant’s negligent act, the injury would not have occurred.  However, in some cases this cannot be shown because it is impossible to determine which of a number of negligent acts in fact caused the injury.  In such cases, the court will apply an exception to the ‘but for’ rule – a plaintiff may be able to recover on the basis of “material contribution to risk of injury”, without showing factual “but for” causation.  Such circumstances, the Court tells us, should be rare.  In general the material contribution test should only be applied where it is impossible to prove the case on a ‘but for’ basis, and there should be evidence that the tortfeasor breached their duty of care, exposing the injured person to unreasonable danger.

In this case, if there had been no nail in the tire, would the speed alone have caused the crash?  What about the overloading of the motorcycle?  It is impossible to say.  Facts such as these raise issues which challenge the traditional test.

The Supreme Court summarized the negligence test as follows:

(1)        As a general rule, a plaintiff cannot succeed unless she shows as a matter of fact that she would not have suffered the loss “but for” the negligent act or acts of the defendant.  A trial judge is to take a robust and pragmatic approach to determining if a plaintiff has established that the defendant’s negligence caused her loss.  Scientific proof of causation is not required.

(2)      Exceptionally, a plaintiff may succeed by showing that the defendant’s conduct materially contributed to risk of the plaintiff’s injury, where (a) the plaintiff has established that her loss would not have occurred “but for” the negligence of two or more tortfeasors, each possibly in fact responsible for the loss; and (b) the plaintiff, through no fault of her own, is unable to show that any one of the possible tortfeasors in fact was the necessary or “but for” cause of her injury, because each can point to one another as the possible “but for” cause of the injury, defeating a finding of causation on a balance of probabilities against anyone.”

The Supreme Court allowed the use of the material contribution test in this case.  The Court stated:

In these circumstances, permitting the plaintiff to succeed on a material contribution to risk basis meets the underlying goals of the law of negligence.  Compensation for injury is achieved.  Fairness is satisfied; the plaintiff has suffered a loss due to negligence, so it is fair that she turns to tort law for compensation.  Further, each defendant failed to act with the care necessary to avoid potentially causing the plaintiff’s loss, and each may well have in fact caused the plaintiff’s loss.