Clements v Clements: Material Contribution to Risk — When the But-For Test Can Be Set Aside and When It Cannot

On August 7, 2004, Joan and Joseph Clements were riding their motorcycle through wet weather in British Columbia, heading from Prince George toward Kananaskis, Alberta. The bike was overloaded by approximately 100 pounds. A nail had punctured the rear tire without Mr. Clements’s knowledge. When he accelerated to at least 120 km/h in a 100 km/h zone to pass a car, the nail fell out, the tire deflated, and the bike began to wobble. He could not regain control. Mrs. Clements was thrown off. She suffered a severe traumatic brain injury.

Mr. Clements’s negligence was not in dispute; he drove an overloaded motorcycle too fast in wet conditions. The only question was whether that negligence caused the accident, or whether the tire deflation alone would have caused the same crash at any safe speed and weight. The trial judge found himself unable to say, with scientific certainty, that the accident would not have happened without the excess speed and weight. He applied a material contribution to risk test and found Mr. Clements liable. The British Columbia Court of Appeal set the judgment aside and dismissed the action. The Supreme Court of Canada ordered a new trial.

In doing so, McLachlin CJ produced for a seven-justice majority the most comprehensive and authoritative statement of Canadian causation law to date: one that confirmed the but-for test as the governing rule, defined the narrow conditions under which material contribution to risk may substitute for it, and clarified once and for all that scientific uncertainty in a single-defendant case does not entitle a plaintiff to bypass the but-for requirement.

The Facts and the Causation Problem

The negligence was straightforward. Joseph Clements drove an overloaded motorcycle at excess speed in wet weather. Both the excess weight (approximately 100 pounds over the rated capacity, or nearly ten percent) and the excess speed (at least 30 km/h above the safe speed for those conditions, as the trial judge found) were established. No one disputed that this conduct was below the standard of care.

What was disputed was whether that conduct caused the crash. Mr. Clements called an expert witness, Mr. MacInnis, who testified that the probable cause of the accident was the tire puncture and deflation, and that the accident would have happened even if the motorcycle had been travelling at a legal speed and without excess cargo. On his analysis, the wobble caused by the nail exiting the tire at any reasonable speed would have been unrecoverable; the excess speed and weight were non-contributing factors.

The trial judge rejected this evidence. He found that Mr. MacInnis had assumed considerably less overloading than the 100 pounds the trial judge found as fact: the expert had assumed no more than 5 percent excess weight, while the trial judge found nearly 10 percent. He also found that Mr. MacInnis had assumed a speed excess of about 12.5 km/h over the recommended speed, while the trial judge found an excess of at least 30 km/h. Most significantly, Mr. MacInnis himself had conceded that his opinion was “largely conjectural” because it “could not be supported scientifically”; there was no reconstruction model that could identify the precise combination of lower speed and lesser weight at which recovery from the wobble would have been achievable.

Having rejected the expert’s evidence, the trial judge was left with the following picture: ordinary common sense suggested the causal relationship was real; the motorcycle’s own manual stated that “high speed increases the influence of any other condition affecting stability and possibility of loss of control”; and Mr. Clements himself agreed that the speed and load were factors that contributed to the accident. But no reconstruction evidence could quantify by precisely how much. The trial judge concluded that Mrs. Clements was “through no fault of her own” unable to prove but-for causation “due to the limitations of the scientific reconstruction evidence.” He applied a material contribution to risk test and found liability.

The Three Courts

Trial — Grauer J. (2009 BCSC 112): Liability Found on Material Contribution

Grauer J. found that Mr. Clements’s negligence “in fact contributed to” Mrs. Clements’s injury. He rejected the defence expert’s opinion that the accident was caused entirely by the tire deflation. He accepted that ordinary common sense supported a causal relationship between the excess speed and weight and the crash. But he held that the plaintiff could not prove “but for” causation because it was impossible to determine through scientific reconstruction at what combination of lower speed and lesser weight the wobble would have been recoverable. He applied the material contribution to risk test and found Mr. Clements liable.

British Columbia Court of Appeal — Frankel J.A. (2010 BCCA 581): Action Dismissed

The BCCA allowed Mr. Clements’s appeal and dismissed the action. The court held that but-for causation had not been proved and the material contribution test did not apply. On the court’s analysis, the critical question was whether, absent the negligence, the accident would have occurred, and there was insufficient evidence to answer that question in the plaintiff’s favour on a balance of probabilities. Material contribution to risk was unavailable because the prerequisites for that exception were not present in a single-defendant case.

Supreme Court of Canada — McLachlin CJ (2012 SCC 32): New Trial Ordered

The SCC allowed Mrs. Clements’s appeal by a 7-2 majority but disagreed with both courts below on the appropriate remedy. The trial judge had made two legal errors that required the matter to be tried again. The BCCA had been wrong to dismiss the action outright. A new trial was ordered.

LeBel and Rothstein JJ. dissented. While agreeing with the majority’s statement of the law, they would have dismissed the appeal rather than ordering a new trial, on the basis that the trial record provided no foundation for a common sense but-for inference and that ordering a new trial was wasteful and contrary to the interests of finality.

The Legal Framework: Causation in Canadian Negligence Law

The General Rule: But-For Causation

McLachlin CJ began with the foundational principle. Proof of negligence alone does not make a defendant liable for a plaintiff’s loss. The plaintiff must also establish causation, the link between the defendant’s breach and the injury. That link is supplied by 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.

The but-for test is inherently a test of necessity: the defendant’s negligence must have been necessary to bring about the injury. If the injury would have occurred anyway, if it was, as lawyers say, “inevitable” regardless of the defendant’s conduct, then the defendant’s negligence did not cause it. The injury was going to happen regardless, and the defendant’s breach of duty is not the cause of the plaintiff’s harm.

The but-for test must be applied, McLachlin CJ confirmed, in a “robust and common sense fashion.” It does not require scientific evidence of the precise contribution the defendant’s negligence made to the injury. A common sense inference of but-for causation from proof of negligence usually flows without difficulty: evidence connecting the breach to the injury may permit the trier of fact, depending on the circumstances, to infer that the defendant’s negligence probably caused the loss. Where but-for causation is established by inference only, it remains open to the defendant to adduce evidence that the accident would have happened anyway, that the negligence was not a necessary cause, but in the absence of such evidence, the inference stands.

This was the framework established in Snell v Farrell, 1990 CanLII 70 (SCC), [1990] 2 SCR 311 (https://canlii.ca/t/1fstw), and Clements v Clements confirmed it without qualification. Scientific proof is not required, has never been required, and the absence of scientific reconstruction evidence does not mean but-for causation cannot be found.

The Exception: Material Contribution to Risk

Exceptionally, courts have accepted that a plaintiff may recover on the basis of material contribution to risk of injury without showing factual but-for causation. McLachlin CJ was at pains to explain the nature of this exception clearly: “But for” causation and material contribution to risk are “two different beasts.” But-for causation is a factual inquiry into what likely happened. Material contribution to risk, by contrast, “does not signify a test of causation at all; rather it is a policy-driven rule of law designed to permit plaintiffs to recover in such cases despite their failure to prove causation.”

This distinction matters enormously. A defendant in a negligence action is a wrongdoer “only in respect of the damage which he actually causes to the plaintiff.” Eliminating proof of causation as an element of negligence is, in McLachlin CJ’s words, “a radical step” at odds with this fundamental principle of corrective justice. For that reason, the exception is necessarily rare; it is justified only where it is required by fairness and conforms to the principles that ground recovery in tort. The law of negligence requires a defendant who is at fault and a plaintiff who has been injured by that fault, linked in what the court described as “a correlative relationship of doer and sufferer of the same harm.” Material contribution to risk can be justified only where this relationship exists at the group level, even if it cannot be pinned to any individual defendant.

The Historical Basis of the Exception

McLachlin CJ surveyed the cases that had given rise to the material contribution exception, tracing a line from Cook v Lewis through the UK toxic agent cases to Resurfice Corp v Hanke.

Cook v Lewis, 1951 CanLII 26 (SCC), [1951] SCR 830, involved two hunters who fired simultaneously. One shot struck a third person. Neither defendant could be identified as the shooter, and each pointed the finger at the other, making but-for causation impossible to prove against either individually. The Court held both defendants liable. The logic was that both were negligent and one of them had in fact caused the injury; the plaintiff would not have been injured but for their negligence viewed as a group; denying recovery while allowing both negligent defendants to escape by pointing at each other would have served none of the law’s goals.

Snell v Farrell, addressed in the companion article in this series, had resolved the optic nerve atrophy case on a robust but-for inference, without in fact applying material contribution. But Sopinka J. had indicated that material contribution might be appropriate if the principles relating to causation proved inadequate to the task.

Resurfice Corp v Hanke, 2007 SCC 7, [2007] 1 SCR 333, involved an ice resurfacer explosion. The plaintiff had poured water into the gas tank by mistake. The trial judge dismissed the action; the court found but-for causation was not established and material contribution was inapplicable. McLachlin CJ’s summary in Resurfice was accurate (impossibility of proving but-for causation, plus clear breach of duty exposing the plaintiff to unreasonable risk), but she found this summary incomplete as a stand-alone test and elaborated it in Clements.

The UK toxic agent cases, Fairchild v Glenhaven Funeral Services Ltd. and Barker v Corus UK Ltd., involved mesothelioma caused by asbestos exposure with multiple employers. A single fibre of asbestos could have caused the disease; it was impossible to say which employer’s fibre did so. Material contribution was applied because each employer had exposed the plaintiff to the same risk, the injury was the kind of risk created by all the defendants, and allowing each employer to point at the others would have allowed all to escape liability for a collectively caused harm. McLachlin CJ noted that Sienkiewicz v Greif (UK) Ltd. had extended this to a single employer in the UK, but declined to follow suit in Canada; the single-defendant material contribution approach has not been adopted here.

When Material Contribution to Risk Is Available: The Two Conditions

McLachlin CJ distilled from this body of case law two conditions that must both be satisfied before material contribution to risk can substitute for but-for causation:

First, the plaintiff must have 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. The but-for test, applied globally to the group of defendants, must be met. This excludes recovery where the injury “may very well be due to factors unconnected to the defendant and not the fault of anyone”; Sopinka J.’s crucial observation in Snell, carried forward in Clements. If the injury would have occurred anyway regardless of all the defendants’ conduct combined, material contribution cannot rescue the plaintiff.

Second, the plaintiff, through no fault of her own, must be 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, defeating a finding of causation on a balance of probabilities against any one of them individually. This is the “point the finger” problem. Each defendant can say to the court: “It might have been me, but it might have been them; you cannot prove on a balance of probabilities that I was the necessary cause.” Where every defendant in a group of negligent defendants can make this argument, and the argument prevents causation being established against any of them individually, the material contribution exception becomes available.

What “Impossibility” Actually Means

One of the more careful analytical contributions of Clements v Clements is its explanation of what “impossibility” means in this context: the word that had appeared in Resurfice and generated confusion. The trial judge in Clements had found impossibility in the scientific reconstruction sense: it was impossible to model at what precise combination of lower speed and lesser weight the wobble would have become recoverable. McLachlin CJ rejected this as a valid form of “impossibility” for the purpose of triggering material contribution.

“Impossibility” in the relevant sense is not logical impossibility (one can imagine that ballistics testing might have revealed which gun in Cook v Lewis fired the shot, or that advanced science might someday identify which fibre of asbestos from which employer caused mesothelioma in a particular patient). It is also not scientific impossibility, the mere absence of scientific reconstruction evidence capable of proving causation with precision. The law has never required scientific proof of causation. Since its absence is not required, its absence cannot be a basis for displacing the but-for test.

The impossibility the exception addresses is practical, multi-party impossibility: where there are multiple negligent tortfeasors and each can defeat the but-for test by pointing to the others, it is genuinely impossible, in any practical sense, for the plaintiff to establish which defendant’s act was the necessary cause. That is the impossibility that justifies the exception. A difficulty of evidentiary proof in a single-defendant case is not.

Single-Defendant Cases: Material Contribution Is Not Available

One of the most practically significant holdings in Clements is the clear statement that material contribution to risk does not currently apply in single-defendant cases in Canada. The trial judge’s error in Clements was precisely this: it was “a simple single-defendant case” where the only issue was whether but-for the defendant’s negligent conduct the injury would have been sustained. That question must be resolved by applying the but-for test robustly and pragmatically. If the plaintiff cannot establish but-for causation on that test, the defendant is not liable.

The UK Supreme Court had gone further in Sienkiewicz, applying material contribution even where a single employer was the only negligent party, bound by precedent from the mesothelioma cases. McLachlin CJ observed that several members of the UK court had noted the difficulty of that result, and declined to follow it in Canada. Nothing in the logic of the exception, which turns on the fairness of allowing multiple defendants to collectively evade liability, requires or supports applying it to single defendants.

The Two Errors at Trial and the Remedy

Error One: Requiring Scientific Reconstruction Evidence for But-For Causation

The trial judge found that Mrs. Clements was unable to prove but-for causation because “after the fact, it is not possible through accident reconstruction modelling to determine at what combination of lower speed and lesser weight recovery from the weave instability would have been practicable.” This was a legal error. Scientific precision is not necessary to a conclusion that but-for causation is established on a balance of probabilities. The absence of accident reconstruction modelling does not mean but-for causation cannot be inferred from the other evidence. The trial judge had already rejected the defence expert’s opinion that the accident would have happened regardless. He had found ordinary common sense supported the causal connection. The motorcycle manual itself supported it. The defendant’s own evidence supported it. These were capable of grounding a but-for inference without a reconstruction model.

Error Two: Applying Material Contribution in a Single-Defendant Case

The trial judge’s second and more fundamental error was applying material contribution to risk to a single-defendant negligence case. The prerequisites for that exception (multiple tortfeasors, a globally satisfied but-for test viewed across the group, and inability to identify which individual defendant’s act was necessary) were simply absent. There was one defendant: Mr. Clements. The question was straightforwardly whether his negligence caused the accident. Material contribution had no role to play.

The Remedy: New Trial Rather Than Dismissal

The majority found it could not be certain what the trial judge would have concluded had he not made these two errors. The trial judge had, notably, used language that came close to a finding of but-for causation when he wrote: “her injuries were the result of her husband driving too fast with too heavy a load when his rear tire unexpectedly deflated.” This formulation sounds in but-for terms; it identifies the overloading and excess speed as the operative causes of the crash. Had the trial judge understood that he did not need scientific reconstruction evidence to make that inference, he might well have found but-for causation established. A new trial was therefore the appropriate remedy rather than outright dismissal.

The dissent (LeBel and Rothstein JJ.) took the opposite view on remedy. The trial judge’s key finding had been that but-for causation was not proved; his conclusion that material contribution was satisfied could not be reinterpreted as a finding of but-for causation without undermining the important distinction between the two tests. In the dissent’s view, there was simply no factual foundation in the record for a robust but-for inference, and ordering a new trial was inconsistent with the need for finality and efficiency in civil litigation.

What Clements v Clements Establishes

Principle One: But-For Causation Remains the General Rule — Always

Clements v Clements confirms, emphatically and comprehensively, that but-for causation is the governing test for causation in Canadian negligence law. It is a factual test: the plaintiff must show, on a balance of probabilities, that the defendant’s negligence was a necessary cause of the injury. Common sense inference, robustly applied, is sufficient, but the finding must still be but-for causation, not something weaker. The absence of scientific evidence supporting the causal theory does not alone entitle a plaintiff to succeed. If but-for causation cannot be established on all available evidence, the claim fails, unless the narrow material contribution exception applies.

Principle Two: Material Contribution to Risk Is a Policy Exception, Not an Alternative Causation Test

Material contribution to risk is not a test for causation. It is a “policy-driven rule of law” that allows courts to find liability in specific circumstances despite the plaintiff’s inability to prove causation. Because it bypasses the fundamental requirement that a defendant be liable only for the harm they actually cause, it must be applied sparingly. It cannot be invoked simply because causation is difficult to prove, because scientific evidence is unavailable, or because the plaintiff faces a hard case. The exception requires that it be “required by fairness” and that it conform to the underlying principles of the law of negligence.

Principle Three: The Two Conditions That Must Both Be Met

Material contribution to risk is available only where: (a) the plaintiff has established that the loss would not have occurred but for the negligence of two or more tortfeasors viewed as a group; and (b) the plaintiff is unable, through no fault of her own, to show which individual defendant’s negligence was the necessary cause of the injury, because each defendant can point to the others. Both conditions must be satisfied. A case involving a single defendant cannot meet condition (b) and therefore cannot trigger the exception.

Principle Four: Scientific Uncertainty Does Not Create “Impossibility” in the Relevant Sense

The impossibility that justifies the material contribution exception is practical multi-party impossibility: the structural situation where multiple tortfeasors can mutually defeat the plaintiff’s causation case by pointing at each other. It is not scientific uncertainty, absence of reconstruction evidence, or difficulty of proof in an ordinary single-defendant case. Since the law has never required scientific proof of causation, the absence of scientific proof cannot be the basis for bypassing the causation requirement. Courts must apply a robust pragmatic inference analysis before concluding that but-for causation is incapable of proof.

Principle Five: The Corrective Justice Foundation of the Exception

McLachlin CJ grounded the material contribution exception in corrective justice: the principle that liability in tort arises when the plaintiff and defendant are in a “correlative relationship of doer and sufferer of the same harm.” In a multi-tortfeasor case where each defendant can point at the others, the plaintiff is in that correlative relationship with the group of defendants viewed collectively, even if she cannot identify which individual caused her harm. Allowing all defendants to escape by mutual finger-pointing would leave the plaintiff uncompensated for harm caused by negligence, frustrating correction of a real injustice. Material contribution to risk restores the corrective relationship at the group level. This logic has no application in single-defendant cases, where either the defendant caused the harm or they did not.

Clements v Clements in the Causation Series

Clements v Clements is the natural sequel to Snell v Farrell in the causation category of this series. Snell established that but-for causation can be proved by robust inference and that scientific certainty is not required. Clements defined the exceptional circumstances, confined, in Canada, to multi-tortfeasor cases with the specific “point the finger” problem, in which the but-for test may be bypassed entirely in favour of material contribution to risk. Together the two cases define the complete causation architecture for Canadian medical malpractice and negligence claims.

In practical terms for the cases in this series: every causation analysis in every medical malpractice case, whether a birth injury, a missed cancer diagnosis, an obstetric error, or a surgical mistake, begins with the but-for test as defined in Snell and confirmed in Clements. Material contribution to risk has no role in the typical malpractice case involving a single defendant physician. Where multiple defendants are involved, as in Uribe v Tsandelis (Dr. Tsandelis and the Grand River Hospital and nurses), the causation analysis may be more complex, but the framework is still Clements: was but-for causation established on a robust pragmatic approach? If not, did the special multi-tortfeasor conditions for material contribution to risk apply?

The article on Uribe v Tsandelis in this series illustrates the tension around causation language in multi-defendant cases, specifically the concern that jurors may express causation findings using “contribution” language in an apportionment context, and how courts have resolved that tension by confirming the but-for test was applied even when the language of contribution appeared in juror explanations.

Quick Reference: Clements v Clements

Case Details

• Clements v. Clements, 2012 SCC 32 (CanLII), [2012] 2 SCR 181 — https://canlii.ca/t/frvld | File No. 34100 | McLachlin CJ (majority, 7-2) | June 29, 2012
• On appeal from the Court of Appeal for British Columbia | Appeal allowed; new trial ordered | LeBel and Rothstein JJ. dissenting: would dismiss the appeal
• Intervener: Attorney General of British Columbia

The Parties and the Facts

• Plaintiff/Appellant: Joan Clements (by litigation guardian Donna Jardine); suffered severe traumatic brain injury when thrown from a motorcycle
• Defendant/Respondent: Joseph Clements — Joan’s husband; the driver; acknowledged negligent (overloaded motorcycle, excessive speed in wet conditions)
• Facts: August 7, 2004; motorcycle approximately 100 pounds overloaded; nail punctured rear tire unknown to driver; driver accelerated to at least 120 km/h in a 100 km/h zone to pass a car; nail fell out, tire deflated, bike wobbled, crashed; Mrs. Clements thrown off; severe traumatic brain injury
• Negligence: Not disputed; excess weight (nearly 10% over rated capacity) and excess speed (at least 30 km/h over safe speed for conditions)
• The causation dispute: Was the negligence (speed + weight) the cause of the unrecoverable wobble? Or would the tire deflation alone have caused the crash at any safe speed and weight?
• Defence expert MacInnis: accident would have happened regardless; trial judge rejected his evidence as based on wrong facts (assumed less overloading and less excess speed than the trial judge found) and “largely conjectural”

The General Rule: But-For Causation

• A plaintiff must show on a balance of probabilities that “but for” the defendant’s negligent act, the injury would not have occurred
• This is a FACTUAL inquiry; the defendant’s negligence must have been NECESSARY to bring about the injury
• Must be applied in a “robust and common sense fashion”, with no need for scientific evidence of the precise contribution (confirming Snell v Farrell)
• Common sense inference of but-for causation from proof of negligence usually flows without difficulty
• Where but-for is established by inference only, it is open to the defendant to adduce evidence that the accident would have happened anyway
• If but-for causation cannot be established, the claim fails, unless the narrow material contribution exception applies

The Material Contribution to Risk Exception

• Material contribution to risk is NOT a test for causation; it is a policy-driven rule permitting recovery despite failure to prove causation
• “But for” causation and material contribution to risk are “two different beasts”: the former is a factual inquiry; the latter bypasses the causation requirement on policy grounds
• Eliminating proof of causation is a “radical step”; a defendant is a wrongdoer only in respect of the damage they actually cause
• Available only where required by fairness AND conforming to the principles that ground recovery in tort

The Two Conditions for Material Contribution to Risk

• Condition 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; the but-for test, viewed globally across the group, is met
• Condition 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; the “point the finger” problem
• BOTH conditions must be met — and a single-defendant case cannot satisfy Condition B

What “Impossibility” Means

• NOT logical impossibility; in principle, many multi-tortfeasor cases could theoretically be solved with better evidence
• NOT scientific impossibility; the law has never required scientific proof; its absence cannot be a basis for bypassing but-for causation
• IS practical multi-party impossibility: where multiple negligent tortfeasors can each point to the others, making it genuinely impossible on a balance of probabilities to identify which individual defendant’s act was the necessary cause
• “Through no fault of her own”: the plaintiff’s inability to prove causation must not be attributable to her own failure to gather evidence

Single-Defendant Cases

• Material contribution to risk does NOT apply in single-defendant cases in Canada (as of Clements v Clements in 2012)
• UK in Sienkiewicz extended material contribution to a single-employer mesothelioma case; NOT followed in Canada
• In a single-defendant case, but-for causation must be established by common sense inference applied robustly and pragmatically
• If but-for causation cannot be established even on a robust pragmatic approach, the claim fails

The Two Trial Errors

• Error 1: Requiring scientific reconstruction evidence as a necessary condition of but-for causation; scientific precision has never been required; a common sense inference from rejected defence expert evidence, the motorcycle’s own manual, and the defendant’s own admissions was available
• Error 2: Applying material contribution in a single-defendant case where the prerequisites for the exception were absent

The Summary of Canadian Law at Paragraph 46

• (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.

Key Cases Referenced

• Snell v. Farrell, 1990 CanLII 70 (SCC), [1990] 2 SCR 311 — https://canlii.ca/t/1fstw — the robust and pragmatic but-for inference; confirmed and elaborated in Clements; article in this series
• Cook v. Lewis, 1951 CanLII 26 (SCC), [1951] SCR 830 — simultaneous negligent shooting; impossible to identify which defendant caused the injury; foundational multi-tortfeasor case
• Athey v. Leonati, 1996 CanLII 183 (SCC), [1996] 3 SCR 458 — disc herniation after motor vehicle accidents; resolved on but-for; 25% contribution was material contribution in name only; actually a but-for case
• Resurfice Corp. v. Hanke, 2007 SCC 7, [2007] 1 SCR 333 — ice resurfacer explosion; but-for not established; material contribution inapplicable; confirmed “special circumstances” requirement
• Walker Estate v. York Finch General Hospital, 2001 SCC 23, [2001] 1 SCR 647 — HIV from tainted blood; resolved on but-for; material contribution acknowledged in obiter as possible in appropriate cases
• Fairchild v. Glenhaven Funeral Services Ltd., [2002] UKHL 22 — UK mesothelioma case; multiple employer asbestos exposure; material contribution to risk applied
• Sienkiewicz v. Greif (UK) Ltd., [2011] UKSC 10 — UK mesothelioma case; single employer; material contribution applied — NOT followed in Canada

Related Cases in This Series

• Snell v. Farrell, [1990] 2 SCR 311 — https://canlii.ca/t/1fstw — the foundational SCC authority on but-for causation by inference; companion case in this series
• Benhaim v. St-Germain — adverse inference from failure to investigate; applies the Snell/Clements framework; article in this series
• Uribe v. Tsandelis, 2021 ONCA 377 — https://canlii.ca/t/jg7mt — multi-defendant case; “contributed to” language in apportionment context; but-for confirmed as the applicable test; article in this series
• Wilton v. Genik, 1998 ONCA — causation failure even after breach established; but-for not satisfied on the evidence; article in this series
• KS v. Willox, 2018 ABCA 271 — https://canlii.ca/t/htrbz — breach proved; causation failed because required intervention was unavailable; article in this series