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Torts - Negligence - Causation (2). Brown v. Meaney
In Brown v. Meaney (Ont CA, 2026) the Ontario Court of Appeal dismissed a defendant's appeal, this brought against a medical negligence claim.
Here the court considers causation, here in a medical negligence case:[37] .... Causation need not be determined by scientific precision: Snell v. Farrell, 1990 CanLII 70 (SCC), [1990] 2 S.C.R. 311, at p. 328. A trier of fact need not come to a single firm conclusion regarding the precise mechanism of injury: Cheung v. Samra, 2022 ONCA 195, 467 D.L.R. (4th) 708 at para. 53, leave to appeal refused, [2022] S.C.C.A. No. 144. The respondents’ burden was merely to show that, on a commonsense basis, but for the appellants’ negligence, Skyler’s injuries would not have occurred. The trial judge determined that this burden had been satisfied. . T.C.O. Agromart Ltd. v. Sutton Farms (Nacona) Ltd.
In T.C.O. Agromart Ltd. v. Sutton Farms (Nacona) Ltd. (Ont CA, 2026) the Ontario Court of Appeal allowed an OLA-negligence appeal, this brought against the dismissal of an action where the court held that "the owner of the land owed no duty to warn users" - here to "stay in the centre of the bridge".
Here the court considers negligence 'standard of care', finding that the trial court erroneously conflated it with it's causation analysis:1. The Lack of Findings on the Standard of Care and Defining the Duty to Warn
[37] As noted above, the trial judge considered causation to be the critical issue, with the result that she approached her determination of liability by assuming without deciding that the first three elements required to establish negligence had been met. She then conducted an analysis to determine whether the conduct of the defendant was the legal and proximate cause of the accident. She did so for efficiency: if the conduct of the defendant was not the cause of the accident, as the trial judge stated, “the inquiry was over.”
[38] In so doing, the trial judge made a reviewable error in the manner in which she first defined the scope of the duty in the circumstances of this case, and then in concluding there was no such duty here.
[39] She then applied that erroneous definition to the causation analysis which led her to conclude that she did not need to make findings with respect to the other elements relevant to a claim of negligence and breach of s. 3(1) of the OLA.
[40] It was common ground at trial that there was no warning of any kind given, either by way of signage posted at the bridge or by way of direct communications to the appellant or its driver.
[41] The basis for the finding of the trial judge that the absence of any warning was not a factual cause of the accident is found at paragraph 96 of the reasons:However, I am not prepared to find that the absence of warnings was a factual cause of the accident. A sign warning Mr. Denyes of the risk of failing to stay in the centre of the Bridge would not have prevented the accident since Mr. Denyes already knew he had to keep the Sprayer centred. Therefore, I find that signs warning of the need to stay in the centre of the Bridge or that the overhang was not supported were not required by s. 3 of the OLA in this case. [42] In my view, the trial judge committed a legal error by conflating causation with the standard of care and effectively failing to perform a standard of care analysis. Once she decided that the presence of signage would not have prevented the accident, she determined that signage was not required to meet the standard of care, and therefore, there was no breach of that standard.
[43] This analysis was an error. The focus of the standard of care analysis must be on the conduct of the bridge owner and what duty he or she owes to all users of the bridge. Using causation as a proxy for the standard of care uses the conduct of one particular injured party to determine the scope of the bridge owner's general duty owed to all users. A lack of causation in one particular case does not mean there was no breach of the standard of care. . T.C.O. Agromart Ltd. v. Sutton Farms (Nacona) Ltd.
In T.C.O. Agromart Ltd. v. Sutton Farms (Nacona) Ltd. (Ont CA, 2026) the Ontario Court of Appeal allowed an OLA-negligence appeal, this brought against the dismissal of an action where the court held that "the owner of the land owed no duty to warn users" - here to "stay in the centre of the bridge".
Here the court considers a negligence 'causation' analysis:2. The Causation Analysis
[53] The third error alleged by the appellant was the trial judge’s application of the erroneously defined duty to warn to find that the breach of that duty was not a factual or legal cause of the injury.
a. Factual Causation
[54] The test for factual causation is the “but for” test, which requires a plaintiff to show on a balance of probabilities that “but for” the defendant’s negligent act or omission, the injury would not have occurred: that is, the defendant’s negligence was necessary to bring about the injury: Clements v. Clements, 2012 SCC 32, [2012] 2 S.C.R. 181, at para. 8; Campbell (ONCA), at para. 53; Hemmings v. Peng, 2024 ONCA 318, at para. 61, leave to appeal granted and appeal heard and reserved February 10, 2026, [2024] S.C.C.A. No. 262 and [2024] S.C.C.A. No. 265.
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[59] The trial judge made a reviewable error by considering that evidence in the context of the erroneously defined scope of the duty to warn. She concluded that the absence of warnings was not a factual cause of the accident because a sign warning the driver of the risk of failing to stay in the centre of the bridge would not have prevented the accident since he already knew he had to stay in the centre of the bridge.
[60] That conclusion becomes incorrect when the duty to warn is properly considered as including a warning that the outer three feet on either side of the bridge were completely unsupported. That would have impacted the driver’s decision to cross the bridge with the sprayer in the manner that he did.
[61] It follows that factual causation was established.
b. Legal Causation
[62] In determining whether the breach of the duty to warn of the hidden danger was a legal cause of the accident, the trial judge correctly noted that a defendant will not be found liable for damages that were caused by their actions if those damages were not reasonably foreseeable: Hemmings, at paras. 67-68.
[63] Foreseeability is assessed in the circumstances of a reasonable person in the position of the particular defendant: Hemmings, at paras. 67-68; and Mustapha, at para. 13.
[64] Whether or not something is “reasonably foreseeable” is an objective test, and is focused on whether someone in the defendant’s position ought reasonably to have foreseen the harm, rather than whether the specific defendant did: Rankin (Rankin’s Garage & Sales) v. J.J., 2018 SCC 19, [2018] 1 S.C.R. 587, at para. 53. This is a question of mixed fact and law.
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[73] Even if experienced drivers knew as a matter of common sense that they had to keep their vehicles centred on the bridge, it was nonetheless foreseeable that one driving heavy farm equipment might veer slightly to the left or the right onto the unsupported overhang, risking an accident such as the one that occurred here. The fact that there had been no such previous incidents on the bridge does not negate the foreseeability of the risk, nor the respondent’s duty of care to take precautions against such harm: Campbell v. Bruce County (ONSC), 2015 ONSC 230, at para. 206, aff’d 2016 ONCA 371.
[74] For these reasons, I am of the view that the accident that occurred here was reasonably foreseeable, with the result that the failure to warn was both a legal and factual cause of the accident. . Shaw Estate v. Handler
In Shaw Estate v. Handler (Ont CA, 2025) the Ontario Court of Appeal dismissed an appeal, this brought against "a judgment in a delayed diagnosis medical malpractice case that proceeded to trial against one defendant, the appellant, on the issues of liability and damages. The appeal concerns only the trial judge’s determination with respect to liability".
The court considered 'causation', here in this medical malpractice context:[58] The framework for determining whether causation is established in a delayed diagnosis case requires the trier of fact to (1) determine what likely happened in actuality; and (2) consider what would likely have happened, if the defendant had not breached the standard of care. And because it is not enough that adequate diagnosis and treatment would have led to a chance of avoiding the unfavourable outcome, the court must determine whether the plaintiff has proven that it was “more likely than not” that the defendant’s compliance with the standard of care would have avoided such an outcome: Hasan v. Trillium Health Centre Mississauga, 2024 ONCA 586, 499 D.L.R. (4th) 178, at para. 20, leave to appeal refused, Campbell v. Hasan, [2024] S.C.C.A. No. 402.
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[69] In some delayed diagnosis cases, including the following cases referred to by the appellant, the central causation issue will require the court to determine at what point the physician’s negligence would not have caused the patient’s injury. Depending on the evidence, the resolution of the issue will depend on determining exactly when the “window of opportunity” would have closed.
[70] In Salter v. Hirst, 2011 ONCA 609, 107 O.R. (3d) 236, leave to appeal refused, [2011] S.C.C.A. No. 503, the breach of the physician’s standard of care was in failing to promptly transfer the plaintiff to another hospital for surgery, and there was clear evidence of a six hour “window of opportunity” between the onset of the plaintiff’s lower extremity symptoms and when the surgery would be required to avoid paralysis. This court dismissed the appeal from a dismissal of the action, concluding that the trial judge was correct in finding there was no evidence that the correct diagnosis likely would have been made and successful treatment likely would have been completed within the critical six-hour period.[6]
[71] Similarly, in Barker v. Montfort Hospital, 2007 ONCA 282, 278 D.L.R. (4th) 215, leave to appeal refused, [2007] S.C.C.A. No. 299, this court allowed an appeal, as there was no medical or other evidentiary basis for the trial judge’s inference that the delay in carrying out an operation caused the death of the plaintiff’s bowel. No expert was asked for an opinion as to whether the plaintiff’s bowel had been necrotic for less than the time it would have taken to carry out the operation. Instead, the evidence was consistent with the bowel already progressing to full strangulation before surgery could have occurred,11:00 p.m. at the earliest, and there was no basis for finding on a balance of probabilities that the bowel died only after surgery would have been performed.
[72] And in Farej v. Fellows, 2022 ONCA 254, leave to appeal refused, [2022] S.C.C.A. No. 180, this court allowed an appeal and directed a new trial, in part, because the trial judge, in concluding that the physician’s decision to proceed with a vaginal delivery of the infant plaintiff rather than an emergency C-section was not the cause of the plaintiff’s injuries, had failed to make the important factual determination of the timeframe within which the emergency C-section could have been completed – in respect of which there was conflicting evidence. . Gumbley v. Vasiliou
In Gumbley v. Vasiliou (Ont CA, 2025) the Ontario Court of Appeal dismissed a medical malpactice appeal, here brought against "trial judge’s causation finding that her breaches of the standard of care more likely than not caused Ms. Gumbley’s brain damage".
The court considers the law of causation, here in this medical malpractice case:[9] The trial judge’s determinations of credibility, reliability and the weight to place on expert evidence attract appellate deference in the absence of palpable and overriding error. One of the main contested issues on this appeal is whether the trial judge erred by relying on the contents of Dr. Warner’s note.
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1. The Need for a Causal Link
[15] There is no doubt that Dr. Vasiliou owed Ms. Gumbley a duty of care as her most responsible physician; she no longer contests that she breached the applicable standard of care. Did Dr. Vasiliou’s breaches cause Ms. Gumbley’s injuries?
a. The Governing Principles
[16] Chief Justice McLachlin’s statement in Clements v. Clements, 2012 SCC 32, [2012] 2 S.C.R. 181, at para. 8, sets the causation test in negligence cases:The plaintiff must show on a balance of probabilities that “but for” the defendant’s negligent act, the injury would not have occurred. Inherent in the phrase “but for” is the requirement that the defendant’s negligence was necessary to bring about the injury – in other words that the injury would not have occurred without the defendant’s negligence. This is a factual inquiry. If the plaintiff does not establish this on a balance of probabilities, having regard to all the evidence, her action against the defendant fails. [Emphasis in original.] [17] Chief Justice McLachlin noted, at para. 46: “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.” She added: “Scientific proof of causation is not required.” At paras. 9, 20, 23, and 28, she reiterated the view that the court should take “a robust and common sense” approach to the application of the test.
[18] Instances of medical malpractice fall into two categories in causation analysis, or a combination of the two. The first are instances in which the doctor does something that should not have been done – acts of commission: see e.g., Armstrong v. Royal Victoria Hospital, 2019 ONCA 963, 452 D.L.R. (4th) 555, rev’d Armstrong v. Ward, 2021 SCC 1, [2021] 1 S.C.R. 3 (surgeon used a tool that caused adhesions and scarring, blocking patient’s ureter); Dallner v. Gladwell, 2024 ONSC 6557 (surgeon applied excessive degree or duration of force or stretch to patient’s arm during surgery); and Kotorashvili v. Lee, 2024 ONSC 1495 (surgeon prematurely removed a clavicle implant plate from the patient’s body). The second category comprises instances in which the doctor fails to do something that should have been done – acts of omission: see e.g., Aristorenas v. Comcare Health Services (2006), 2006 CanLII 33850 (ON CA), 83 O.R. (3d) 282 (C.A.), leave to appeal refused, [2006] S.C.C.A. No. 487 (treating physician and nurses failed to adequately and promptly treat post-surgery infection); Sacks v. Ross, 2017 ONCA 773, 417 D.L.R. (4th) 387, leave to appeal refused, [2017] S.C.C.A. No. 491 (diagnosis and treatment of anastomotic leak in patient was delayed); Beldycki Estate v. Jaipargas, 2012 ONCA 537, 295 O.A.C. 100 (radiologist failed to see visible lesion in patient’s liver on CT scan); and Hasan v. Trillium Health Centre (Mississauga), 2024 ONCA 586, 499 D.L.R. (4th) 178, leave to appeal refused, Campbell v. Hasan, [2024] S.C.C.A. No. 402 (treating physician failed to consult with neurologist and order brain imaging for patient in timely manner).
[19] Dr. Vasiliou’s breaches of the standard of care are acts of omission. The required chain of reasoning was set out in Sacks, at paras. 46-48, and in Hasan, at para. 16, citing Sacks. The trier of fact’s thought process in determining factual causation has two steps. The first is to determine what likely happened in actuality. The second, explained at para. 48 of Sacks, is to consider what likely would have happened had the defendant not breached the standard of care:There are two possible outcomes to the trier of fact’s imaginative reconstruction of reality at the second step. On the one hand, if the trier of fact draws the inference from the evidence that the plaintiff would likely have been injured in any event, regardless of what the defendant did or failed to do in breach of the standard of care, then the defendant did not cause the injury. On the other hand, if the trier of fact infers from the evidence that the plaintiff would not likely have been injured without the defendant’s act or failure to act, then the “but for” test for causation is satisfied: but for the defendant’s act or omission, the plaintiff would not have been injured. The defendant’s fault, which justifies liability, has been established. [20] The trial judge cited the test in Sacks at para. 217 of his reasons.
[21] I agree with Dr. Vasiliou that, as Laskin J.A. noted in Chasczewski v. 528089 Ontario Inc. (Whitby Ambulance Service), 2012 ONCA 97, 287 O.A.C. 266, at para. 15, the test for causation stipulates that “it is the defendant’s particular substandard act or omission that must be shown to have caused the harm; therefore, it is necessary to identify that act or omission to determine what, if any, connection it has to the harm at issue.”
[22] In other words, as Rouleau J.A. observed in Aristorenas, at para. 54:The “robust and pragmatic” approach is not a distinct test for causation but rather an approach to the analysis of the evidence said to demonstrate the necessary causal connection between the conduct and the injury. Importantly, a robust and pragmatic approach must be applied to evidence; it is not a substitute for evidence to show that the defendant’s negligent conduct caused the injury. . N.S. v. Ukraine International Airlines PJSC
In N.S. v. Ukraine International Airlines PJSC (Ont CA, 2025) the Ontario Court of Appeal dismissed an appeal, here from the trial judge's finding that the defendant to a class proceeding (and to numerous individual proceedings) had "failed to prove, on a balance of probabilities, that it was not negligent", which dictated that they are not damage-limited by the Montreal Convention (for air travel).
Here the court considers negligence 'causation' of damages:[71] The trial judge correctly identified the “but for” test for causation as the governing principle: Clements v. Clements, 2012 SCC 32, [2012] 2 S.C.R. 181, at paras. 8 and 13. The trial judge utilized a three-step approach: (1) determine what likely happened; (2) consider what likely would have happened if the defendant had not breached the standard of care; and (3) allocate fault among the negligent defendants: Sacks v. Ross, 2017 ONCA 773, 417 D.L.R. (4th) 387, at para. 47, leave to appeal refused, [2017] S.C.C.A. No. 491. The third step is not applicable in this case because UIA is vicariously responsible for the negligence or other wrongful acts or omissions of the carrier or its servants or agents. . Algra v. Comrie Estate
In Algra v. Comrie Estate (Ont CA, 2023) the Court of Appeal considered lawsuits emanating from a fatal boat accident. In these quotes the court considers aspects of negligence, here causation:(c) Material Contribution Test
[18] The Liability Appellants submit that the motion judge erred in law in not adopting the “material contribution to risk test” in his causation analysis. They argue that they should be able to recover on the basis of “material contribution to risk,” without showing factual “but for” causation. I would not give effect to this submission. The motion judge properly applied the “but for” test rather than the “material contribution to risk” test.
[19] Generally, the test for showing causation is the “but for” test, i.e., liability follows when the plaintiff establishes on a balance of probabilities that “but for” the defendant’s negligent act, the injury would not have occurred. This is a factual inquiry. In some cases, an injury may flow from several different negligent acts committed by different actors, each of which is a necessary or “but for” cause of the injury. In those cases, the defendants will be jointly and severally liable and the trier of fact will apportion liability according to the degree of fault of each defendant pursuant to contributory negligence legislation: Clements v. Clements, 2012 SCC 32, [2012] 2 S.C.R. 181, at paras. 8, 12.
[20] Despite the foregoing, in exceptional circumstances, where it is impossible to prove causation on the “but for” test, a plaintiff may be able to recover on the basis of a “material contribution to risk of injury,” without showing factual “but for” causation: Clements, at paras. 13, 37. This test can apply where there are multiple tortfeasors if the plaintiff can establish that but for their actions globally an injury would not have resulted, but they cannot show which of several negligent defendants actually caused the injury: Clements, at para. 46. Thus, the material contribution test is only appropriate where it is impossible for a plaintiff to prove which of several defendants caused the plaintiff’s injury using the “but for” test: Clements, at para. 40.
[21] The law in this regard was summarized by McLachlin C.J. at para. 46 of Clements:(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. [22] Elimination of proof of causation as an element of negligence is a radical step that goes against the fundamental principle that a defendant in an action in negligence is a wrongdoer only in respect of the damage which he actually causes to the plaintiff. For that reason, “recourse to a material contribution to risk approach is necessarily rare, and justified only where it is required by fairness and conforms to the principles that ground recovery in tort”: Clements, at para. 16.
[23] In the case at bar, it was not impossible for the Liability Appellants to establish “but for” causation. They did so with respect to Comrie and Monteiro. The problem was that they failed to meet their onus of establishing the essential prerequisite for the adoption of the “material contribution to risk” test, i.e., the existence of multiple potentially contributing tortfeasors. In other words, the Liability Appellants failed to establish that they are in a correlative relationship of doer and sufferer of the same harm with the Government Respondents. Considerations of fairness were not engaged because there is nothing inherently unfair in finding that the actions of Comrie and Monteiro were the only causes of the accident and that the actions of the Government Respondents were not a cause. Thus, the “material contribution to risk” test was not in play and the motion judge made no error in utilizing the “but for” test. . Willick v. Willard
In Willick v. Willard (Ont CA, 2023) the Court of Appeal considered 'causation', here in a medical malpractice context:[43] The appellants argued causation before they argued whether the standards of care were breached and relied on this court’s decision in Sacks v. Ross, 2017 ONCA 773, 417 D.L.R. (4th) 387 as authority for doing so. They cite para. 47, where, writing for the court, I said:Regardless of whether the defendant's breach of the standard of care is an act or an omission, the trier of fact’s cognitive process in determining causation has three basic steps. The first is to determine what likely happened in actuality. The second is to consider what would likely have happened had the defendant not breached the standard of care. The third step is to allocate fault among the negligent defendants. [44] The appellants submit that the trial judge failed to clearly apply the requisite three-step causation analysis. With respect, that is not the correct reading of para. 47 of Sacks, which is not a prescription that mandates a particular analytical framework but a description of the reasoning process in an ordinary case. The trial judge did not err by engaging in a different process.
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