Fedoriuk v Howard: But-For Phrasing and the Jury Particulars Question in Delayed Diagnosis

Causation is the single most contested issue in modern Canadian medical malpractice law. It is also the issue on which the most consequential plaintiff outcomes turn. Where the standard of care has clearly been breached but the consequences would have unfolded similarly even with reasonable care, the case fails on causation. Where the standard of care has been met or the technical details are contested, causation can sometimes be inferred from the seriousness of the outcome and the plausibility of an alternative trajectory. The doctrinal framework for causation has been refined through a series of Supreme Court of Canada and provincial appellate decisions over the past two decades, but the application of that framework at trial, particularly in jury trials, remains an area of active debate. Jury malpractice trials in Ontario are now relatively rare, and where they do occur, the precise wording of the questions put to the jury can determine the outcome.

Fedoriuk v Howard, 2025 ONSC 2534, released by the Ontario Superior Court of Justice on April 25, 2025, is a recent mid-trial ruling addressing two interconnected questions about jury instructions in a delayed-diagnosis medical malpractice case. The first question was whether the causation question put to the jury should use the strict “but-for” formulation favoured by the defence or the broader “caused or contributed to” formulation favoured by the plaintiff. The second was whether the jurors should be required to provide written reasons explaining how they reached their causation findings. The trial judge adopted the defendants’ “but-for” formulation and declined to require the jurors to provide reasons.

The case is doctrinally important for several reasons. It is a recent application of the framework articulated by the Ontario Court of Appeal in Surujdeo v Melady, 2017 ONCA 41 and Sacks v Ross, 2017 ONCA 773, which left the field with some live ambiguity about the appropriate phrasing of jury causation questions. It addresses the parallel debate about whether jurors should be required to provide particulars of their reasoning, an issue that has produced inconsistent treatment in trial-level decisions since Cheung v Samra. It applies the framework specifically in the context of a catastrophic neurological injury allegedly arising from inadequate emergency department triage and reassessment. And it adds another data point to the strategic landscape of jury trials in Ontario medical malpractice litigation, which industry commentary has identified as increasingly defendant-favourable in delayed-diagnosis cases.

The legal framework — causation in Canadian malpractice law

A brief overview of the legal framework is useful before turning to the case.

The but-for test. The Supreme Court of Canada in Clements v Clements, 2012 SCC 32 affirmed that the “but-for” test is the primary test for causation in Canadian negligence law. The test asks whether, but for the defendant’s breach of the standard of care, the plaintiff would have suffered some harm. The test is applied on the balance of probabilities. Where the answer is yes (the plaintiff would not have suffered the harm but for the breach), causation is established. Where the answer is no (the harm would have occurred regardless), the case fails on causation regardless of how serious the breach.

The but-for test operates as a counterfactual inquiry. The trier of fact considers what would have happened had the defendant exercised reasonable care, and compares that counterfactual scenario with the actual outcome. The counterfactual reasoning is itself an area of substantial complexity in modern malpractice cases (see, for example, Yang v Freed, 2024 ABKB 597, where the counterfactual reasoning failed because the temporal disconnection between the alleged breach and the eventual outcome could not be bridged on the available evidence).

The robust and pragmatic approach. The Supreme Court of Canada in Snell v Farrell, [1990] 2 SCR 311 and reaffirmed in Benhaim v St-Germain, 2016 SCC 48 articulated a “robust and pragmatic” approach to the causation inquiry. The framework recognizes that scientific certainty is rarely available in medical malpractice causation, that the patient typically does not have access to all the relevant information, and that the trier of fact should not require a higher standard of proof than the balance of probabilities. The framework permits the trier of fact to draw inferences about causation from the available evidence even where direct proof of the counterfactual is unavailable.

The material contribution test. The Supreme Court of Canada in Resurfice Corp v Hanke, 2007 SCC 7 and Clements v Clements identified a narrow set of circumstances in which the strict but-for test can be modified to a “material contribution to risk” test. The exceptional circumstances are typically described as cases of multiple potential tortfeasors where the but-for test would be unworkable because of “circular causation” (it is impossible to tell which tortfeasor’s act actually caused the harm). The material contribution framework is exceptional and is reserved for cases that meet the specific criteria. The Supreme Court has emphasized that material contribution is not a backstop for difficult but-for cases; it applies only where the but-for framework genuinely cannot work.

The Surujdeo–Sacks divergence. The Ontario Court of Appeal addressed the question of how causation should be framed for juries in two 2017 decisions issued within months of each other. In Surujdeo v Melady, the court held that the jury question should use “but-for” language and not “caused or contributed to.” The court was concerned that “caused or contributed to” could be misunderstood as introducing a material contribution analysis where the case did not warrant it. In Sacks v Ross, a delayed-diagnosis case involving multiple healthcare providers, the court held that “caused or contributed to” was embodied in the but-for test and was appropriate language for juries, particularly in multi-defendant cases.

The result has been some uncertainty in trial practice. Cheesman v Credit Valley Hospital, 2019 ONSC 4996 followed Sacks. Doobay v Fu, 2020 ONSC 1774 addressed similar terrain. Trial judges have to make a case-specific assessment of whether the strict Surujdeo approach or the more flexible Sacks approach is appropriate, with reference to the structure of the alleged negligence (sequential vs cumulative; single defendant vs multiple defendants; whether the case involves the specific complications that motivated Sacks).

The Cheung v Samra particulars question. Separately, trial-level decisions have addressed whether jurors should be required to provide written particulars explaining how they reached their causation findings. In Cheung v Samra, Justice Wilson refused to enter the jury’s verdict because the jurors’ answers to the causation questions were inadequate. She ordered a new trial. The decision is now sometimes cited for the proposition that jurors should be required to provide detailed reasoning, on the view that the requirement promotes the application of the correct legal standard and reduces the risk of emotional or speculative reasoning. The contrary view, articulated by plaintiff-side commentators, is that requiring particulars puts plaintiffs at a disadvantage because it suggests that all jurors must share the same reasoning, when in fact each juror’s reasoning need only lead to a finding of negligence on the balance of probabilities. The requirement of particulars also creates additional grounds for appellate challenge to verdicts.

The strategic significance. Industry commentary has noted that plaintiffs have been losing a high proportion of delayed-diagnosis medical malpractice trials in Ontario in recent years. The reasons are debated, but the precise framing of causation questions and the requirement of particulars are widely understood to play a meaningful role in the outcomes.

The clinical context — cerebral aneurysm and emergency triage

A brief clinical overview of the underlying case is useful for the analysis.

Cerebral aneurysm. A cerebral aneurysm is a balloon-like dilation of a cerebral artery wall, typically at a branch point. Aneurysms can remain asymptomatic for years and are sometimes discovered incidentally on brain imaging done for other reasons. The principal clinical concern with aneurysms is rupture. Rupture produces bleeding into the subarachnoid space (subarachnoid hemorrhage, SAH) or into the brain parenchyma (intracerebral hemorrhage), depending on the location and direction of the rupture.

Sentinel hemorrhage. A sentinel hemorrhage is an initial, often smaller, bleed that precedes a larger rupture. The sentinel bleed may produce a sudden severe headache (classically described as the “worst headache of life”), neck stiffness, photophobia, transient neurological symptoms, or focal deficits depending on the location and size. The recognition of sentinel hemorrhage is critical because intervention between the sentinel bleed and a subsequent re-rupture can substantially alter the outcome. Patients who receive prompt diagnosis and intervention after a sentinel bleed have substantially better outcomes than those whose sentinel bleed is missed and who go on to suffer a larger re-rupture.

Re-rupture risk. After the initial rupture, the risk of re-rupture is highest in the first 24 to 48 hours. Re-rupture is associated with substantially worse outcomes, including markedly higher mortality and disability rates. The clinical priority after diagnosis of an aneurysm-related hemorrhage is to secure the aneurysm before re-rupture can occur, typically through endovascular coiling or surgical clipping.

Intervention. Modern intervention for ruptured cerebral aneurysm involves either:

• Endovascular coiling (a catheter-based technique in which platinum coils are placed inside the aneurysm to promote thrombosis and occlusion)
• Surgical clipping (an open neurosurgical procedure in which a clip is placed across the aneurysm neck)

The choice depends on aneurysm location, anatomy, and patient factors. Both approaches aim to prevent re-rupture and to allow the patient to recover from the initial bleed without further insult.

CTAS triage. The Canadian Triage and Acuity Scale (CTAS) is the standard triage system used in Canadian emergency departments. It assigns patients to one of five levels based on the urgency of their condition:

• Level 1 (Resuscitation): life-threatening conditions; immediate assessment and intervention
• Level 2 (Emergent): potentially life-threatening conditions; reassessment by physician within 15 minutes
• Level 3 (Urgent): conditions that could progress to a serious problem if not addressed; reassessment by physician within 30 minutes
• Level 4 (Less urgent): within 60 minutes
• Level 5 (Non-urgent): within 120 minutes

The framework also specifies reassessment intervals for patients waiting to be seen. Patients assigned Level 2 should be reassessed every 15 minutes; Level 3 patients every 30 minutes. The reassessment is meant to identify clinical deterioration before the patient’s condition becomes critical.

The triage choice in suspected aneurysm. A patient presenting with focal neurological symptoms (numbness on one side of the body, tinnitus or other auditory symptoms, severe sudden headache) raises the differential of cerebrovascular pathology, including aneurysm, stroke, or hemorrhage. The standard of practice for triage nurses includes specific recognition of neurological symptom patterns that warrant higher-acuity triage. A patient with focal neurological symptoms is typically a candidate for at least Level 2 triage given the time-sensitivity of cerebrovascular interventions.

Left without being seen (LWBS). “Left without being seen” or LWBS is a recognized phenomenon in Canadian emergency departments. A patient who waits too long and leaves before assessment is typically a sign of system overload or inadequate reassessment of waiting patients. Hospital policies typically include LWBS tracking and follow-up. Where a patient with a high-acuity condition leaves without being seen and subsequently deteriorates, the failure to provide timely assessment and the failure to identify the deterioration in the waiting room can both be the subject of malpractice scrutiny.

Nursing reassessment. The CTAS framework and modern emergency nursing practice both include the requirement of meaningful reassessment of patients waiting to be seen. Reassessment is not just visual observation from across the room. It is an active engagement with the patient that includes vital signs, symptom check, and clinical evaluation. A visual observation that the patient is “using their phone with no signs of visible distress” is not a meaningful reassessment under modern nursing standards.

The facts

The plaintiff was a 21-year-old man who presented to a community hospital emergency department complaining of tinnitus in the left ear and numbness on the left side of his body. The presentation included clinical features suggestive of possible cerebrovascular pathology.

The initial triage. At 1:02 PM, the plaintiff was triaged by Nurse Howard. He was assigned CTAS Level 3 (urgent; reassessment within 30 minutes; suggesting his condition could potentially progress to something serious). He was instructed to wait in the waiting room for physician assessment.

The “reassessment.” At 2:22 PM (approximately 80 minutes after initial triage), Nurse Bauer observed the plaintiff using his phone with no signs of visible distress. Without engaging with the plaintiff or performing a substantive reassessment, Nurse Bauer characterized this observation as her reassessment.

The walkout. At 3:20 PM (approximately 2 hours and 18 minutes after triage), the plaintiff walked out of the hospital. He had not been assessed by a physician at any point. The plaintiff later alleged that the wait time and the lack of meaningful reassessment were factors in his decision to leave.

The collapse. Approximately 30 minutes after leaving the hospital, the plaintiff collapsed. He was transported back to the hospital by ambulance. From there he was transferred to a tertiary care hospital where neurological imaging revealed a large intracerebral hemorrhage caused by a ruptured cerebral aneurysm.

The clinical sequence. The expert evidence at trial suggested that the plaintiff had already suffered an initial ruptured aneurysm by the time of Nurse Howard’s triage (the sentinel bleed). The second event was a re-rupture, which produced the large intracerebral hemorrhage seen on subsequent imaging. The clinical pattern is consistent with the sentinel hemorrhage / re-rupture framework outlined above.

Emergency surgery. The plaintiff underwent emergency neurosurgery. He survived but was left with significant permanent impairments, including left-sided hemiparesis (weakness or partial paralysis on the left side of the body), left-sided visual field loss, reduced dexterity in the left hand (described as a fisted hand with limited function), and impairments in executive functioning and disinhibition.

The action. The plaintiff brought a civil action against the two triage nurses (Nurse Howard, who performed the initial triage, and Nurse Bauer, who performed the “reassessment”). The action proceeded to a jury trial.

The contested issues

The plaintiff’s theory. The plaintiff alleged that he should have been assigned CTAS Level 2 (emergent; reassessment within 15 minutes) given the neurological symptoms he presented with. Level 2 triage would have triggered earlier physician assessment, earlier recognition of the sentinel hemorrhage, earlier imaging, and earlier intervention to secure the aneurysm before re-rupture. The plaintiff’s theory was a delay-mitigation theory: the breach did not cause the initial rupture (which had already occurred), but earlier diagnosis and intervention would have prevented or mitigated the re-rupture and the resulting permanent impairments.

The defendants’ theory. The defendants advanced several alternative arguments. First, they denied breaching the standard of care; Level 3 was appropriate triage given the presentation. Second, even if there was a breach, causation was not established. The re-rupture, on their theory, would have occurred regardless of the triage level. The defendants characterized the case as a “loss of chance” case, arguing that the injuries were indivisible and resulted solely from the initial aneurysm rather than from any delay in treatment.

The causation contest. The structure of the causation contest was the standard structure for a delay-mitigation case. The plaintiff had to prove that with timely intervention, the eventual outcome would have been different on the balance of probabilities. The defendants argued that the available evidence could not establish the counterfactual to the required standard, particularly given the unpredictability of aneurysm re-rupture and the timing constraints involved.

The mid-trial ruling

The trial judge was required to make two rulings on the framing of the jury questions before the case went to the jury.

The first ruling: but-for or caused or contributed to. The plaintiff sought to have the causation question framed in the broader “caused or contributed to” language. The defendants sought the stricter “but-for” language.

The trial judge adopted the defendants’ position. The judge’s reasoning included:

• The case involved sequential negligence (Nurse Howard’s triage, followed by Nurse Bauer’s reassessment), not cumulative negligence from multiple parties acting simultaneously
• The structure of the alleged negligence did not present the kind of complications that motivated Sacks v Ross (multiple healthcare providers, multiple causal pathways, the difficulty of isolating the contribution of any one provider)
• Using “caused or contributed to” risked the jury accidentally applying a material contribution analysis, which the Resurfice / Clements framework reserves for exceptional cases
• The standard but-for phrasing was sufficient to capture the causation question on the facts of this case

The ruling situates the case on the Surujdeo side of the appellate divergence rather than the Sacks side. The placement reflects the trial judge’s assessment that this was not a multi-pathway case requiring the broader framing.

The second ruling: requiring jurors to provide reasons. The defendants sought a direction requiring the jurors to provide written reasons explaining how they had reached their causation findings. The plaintiff opposed the requirement.

The trial judge declined to require juror reasons. The reasoning included:

• A requirement of reasons could expose what should remain confidential jury deliberations
• A requirement of reasons could create grounds for the verdict to be set aside if the jurors had difficulty articulating their reasoning
• Jurors are laypersons without legal or medical training; the framework should not require them to provide detailed legal analysis
• Requiring reasons risks each juror feeling they must share identical reasoning with the other jurors, when in fact each juror need only reach a finding on the balance of probabilities by whatever route the evidence supports for that juror

The trial judge acknowledged the contrary argument (that requiring reasons helps ensure the jury applies the correct legal standard and reduces the risk of emotional or speculative reasoning) but found that the shortcomings of the requirement outweighed its potential benefits.

The ruling on particulars is at odds with the approach taken in Cheung v Samra and reflects the underlying tension in Ontario trial practice. The framework will likely receive further appellate attention before it stabilizes.

The doctrinal anchors

Several doctrinal anchors emerge from the case.

The but-for test as default causation framework. The Supreme Court of Canada framework in Clements v Clements applies the but-for test as the primary test for causation in negligence cases. Fedoriuk v Howard applies the framework specifically to jury question framing.

The material contribution test as exceptional. The material contribution to risk framework is reserved for exceptional cases meeting specific criteria. Fedoriuk v Howard reinforces the framework by adopting the strict but-for phrasing on facts that did not warrant the material contribution analysis.

The Surujdeo–Sacks divergence and case-specific application. The Ontario Court of Appeal decisions in Surujdeo and Sacks left the field with some live ambiguity about jury question framing. The case-specific application requires trial judges to assess the structure of the alleged negligence: sequential single-defendant cases tend toward Surujdeo (but-for), while multi-defendant cases with multiple causal pathways tend toward Sacks (caused or contributed to).

The “no reasons required from jurors” framework. The framework recognizes that jurors are laypersons whose deliberations should remain confidential and whose verdict should not be set aside for inadequate articulation of reasoning. The framework is at odds with the approach in Cheung v Samra. The unresolved tension is likely to receive further appellate attention.

The “sequential vs cumulative negligence” framework. Sequential negligence (multiple breaches by sequential actors) is doctrinally distinct from cumulative negligence (multiple breaches by simultaneous actors). The distinction affects the jury question framing and the application of the appellate framework. Fedoriuk v Howard applies the sequential framework to a two-nurse case.

The “delay mitigation” plaintiff theory. Where the underlying pathology has already begun before any breach occurred, the plaintiff theory is typically that earlier intervention would have mitigated (not prevented) the eventual outcome. The framework is generalizable to delayed-diagnosis cases involving conditions with progressive trajectories. Fedoriuk v Howard applies the framework to cerebral aneurysm re-rupture in the context of sentinel hemorrhage.

The “loss of chance” defence framing. Defendants in delay-mitigation cases typically argue that the case is a “loss of chance” case in the sense that the underlying condition would have produced a similar outcome regardless of the breach. The Canadian framework does not recognize loss of chance as an independent cause of action; the framework requires proof on the balance of probabilities that the breach caused the harm. The “loss of chance” framing is a defence argument about why the balance-of-probabilities threshold has not been met.

The “indivisible injury” defence. Where the defendant argues that the injuries are indivisible and would have occurred regardless of the breach, the framework requires the trier of fact to assess whether the alleged breach caused some component of the harm that is distinguishable from the non-negligent baseline. Fedoriuk v Howard presents the indivisible-injury framework specifically in the cerebral aneurysm re-rupture context.

The CTAS triage standard of care framework. The Canadian Triage and Acuity Scale establishes specific clinical standards for emergency department triage. Failure to apply the framework correctly, including failure to recognize neurological symptom patterns that warrant higher-acuity triage, can constitute a breach of the nursing standard of care. Fedoriuk v Howard is the principal cluster authority on the framework.

The “meaningful reassessment” framework. The CTAS framework requires reassessment of waiting patients at specified intervals. Reassessment is an active clinical engagement, not a passive visual observation. A nurse who characterizes a visual observation of a patient using their phone as a reassessment has not met the framework. The doctrinal significance is broad: the framework applies across emergency departments and supports the SOC analysis where a deteriorating patient is not adequately monitored in the waiting room.

The LWBS (left without being seen) framework. Patients who leave the emergency department before being seen by a physician have a recognized worse outcome profile. Where the hospital’s failure to provide timely assessment and meaningful reassessment is the proximate cause of the patient leaving, the framework supports a finding of breach. Fedoriuk v Howard applies the framework in the context of a patient with neurological symptoms.

The sentinel hemorrhage / re-rupture framework. Cerebral aneurysm rupture can occur in two events: an initial sentinel hemorrhage (often smaller and missed) followed by a larger re-rupture. The framework is doctrinally important because it allows the causation analysis to focus on the difference between the sentinel-only outcome (typically much better) and the re-rupture outcome (typically much worse). Fedoriuk v Howard applies the framework in the malpractice context.

Why this ruling matters

For prospective plaintiffs and families. The case illustrates the procedural complexity of medical malpractice jury trials and the importance of the framing of causation questions.

Some practical observations:

Causation framing matters. The wording of the questions put to the jury can affect the outcome. The trend in Ontario in recent years has been toward stricter but-for language in cases that do not involve the specific complications that motivated Sacks v Ross. Plaintiffs in delay-mitigation cases face particular challenges in establishing causation on the balance of probabilities when the framework is applied strictly.

Jury trials in malpractice are rare but consequential. Most medical malpractice cases in Ontario are tried by a judge alone. Where a jury trial is held, the dynamics of jury deliberation, the framing of questions, and the requirement of particulars all become significant strategic considerations. The decision to pursue a jury trial in a malpractice case is a meaningful strategic question that should be discussed in detail with counsel.

Delay-mitigation cases are particularly challenging. Cases in which the underlying pathology had already begun before any breach occurred (delayed diagnosis of cancer, delayed diagnosis of aneurysm sentinel bleed, delayed diagnosis of stroke, and similar patterns) face particular causation challenges. The plaintiff must establish that timely intervention would have changed the outcome on the balance of probabilities, which requires careful expert evidence about the natural history of the condition with and without timely intervention.

Emergency department systems matter. Where the alleged breach is not the failure of any single clinician but the failure of the system (inadequate triage, inadequate reassessment, inadequate monitoring of waiting patients), the case becomes more complex. The framework applies to nursing decisions, hospital policies, and the operation of the triage system more broadly.

For more on the general framework for evaluating medical malpractice cases, see Suing for Medical Malpractice in Ontario: What You Need to Know and Why Many Medical Malpractice Cases Are Declined in Ontario. For more on emergency department dynamics, see Hallway Medicine in Ontario: When Overcrowded Emergency Rooms Lead to Medical Malpractice.

For clinicians and emergency department teams. A few practical observations:

Triage decisions are documented and reviewed. The framework applied to triage nursing in malpractice litigation operates on the contemporaneous record. The triage level assigned, the basis for it, and the subsequent reassessments are all part of the contemporaneous record that supports the SOC analysis.

Meaningful reassessment is the standard. The CTAS framework requires meaningful reassessment of waiting patients at specified intervals. A visual observation across the waiting room does not satisfy the framework. The reassessment should be a substantive clinical engagement that includes vital signs and symptom check.

Neurological symptoms warrant high-acuity triage. Patients presenting with focal neurological symptoms (sudden numbness, weakness, vision changes, severe headache) have a differential that includes time-sensitive cerebrovascular conditions. The framework supports Level 2 triage in these presentations and immediate physician assessment.

LWBS patterns warrant system review. Where patients with high-acuity conditions are leaving the emergency department before being seen, the system itself is a candidate for review. The framework treats LWBS as both a quality-of-care indicator and a potential predictor of malpractice exposure.

Cluster integration

This is a mid-trial procedural ruling in a delayed-diagnosis case. The case joins:

• The procedural ruling cluster alongside Ibrahimova v Cavanagh (discovery motion) and Salamaszynski v Michael Garron Hospital (litigation privilege motion)
• The causation framework cluster alongside Hasan v Trillium Health Centre (plaintiff success on causation), Noel v Lakeridge Health (defendant), Lorencz v Saskatchewan Health Authority (defendant), Yang v Freed (defendant), McMullan (defendant), Tripp v Ross (defendant appellate), and Sacks v Ross (the underlying appellate framework)
• The delayed-diagnosis cluster alongside Sutherland v Encompass Health (stroke), Pellerin v Mistry (appendicitis), McMullan (aortic dissection), and the broader delay-mitigation framework
• The emergency department cluster alongside the ER missed-diagnosis cases and the Hallway Medicine in Ontario foundational post
• The catastrophic neurological injury cluster as a new clinical anchor

For other recent decisions on Ontario malpractice procedure, see Ibrahimova v Cavanagh and Salamaszynski v Michael Garron Hospital. For the broader framework on delayed-diagnosis cases, see Sutherland v Encompass Health and the foundational posts.

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Decision Date: April 25, 2025

Jurisdiction: Ontario Superior Court of Justice

Citation: Fedoriuk v Howard, 2025 ONSC 2534 (CanLII)

Outcome: Mid-trial procedural ruling on the framing of jury questions in a medical malpractice action against two emergency department nurses. The trial judge ruled that the causation question put to the jury would use the strict “but-for” formulation rather than the broader “caused or contributed to” formulation, on the basis that the structure of the alleged negligence was sequential rather than cumulative and that the broader formulation could lead the jury to accidentally apply a material contribution analysis that was not warranted on the facts. The trial judge also declined to require the jurors to provide written reasons explaining how they reached their causation findings, citing concerns about the integrity of jury deliberations, the risk of verdict invalidation for inadequately articulated reasoning, and the inappropriateness of requiring laypersons to provide detailed legal analysis. The ruling reflects the Surujdeo v Melady side of the Ontario Court of Appeal divergence on jury question framing and is at odds with the approach in Cheung v Samra on the question of juror particulars.

Key authorities: Clements v Clements, 2012 SCC 32 (but-for test as primary causation framework); Snell v Farrell, [1990] 2 SCR 311 and Benhaim v St-Germain, 2016 SCC 48 (robust and pragmatic approach to causation); Resurfice Corp v Hanke, 2007 SCC 7 (material contribution test as exceptional); Surujdeo v Melady, 2017 ONCA 41 (but-for language for jury instructions); Sacks v Ross, 2017 ONCA 773 (caused or contributed to as embodied in but-for, particularly in multi-defendant cases); Cheesman v Credit Valley Hospital, 2019 ONSC 4996; Doobay v Fu, 2020 ONSC 1774; Cheung v Samra (verdict set aside for inadequate juror reasoning); ter Neuzen v Korn, [1995] 3 SCR 674 (origin of the particulars debate).