Hasan v Trillium: When the Defendant’s Negligence Creates the Evidentiary Gap

A 40-year-old man presents to a designated Regional Stroke Centre with dizziness, nausea, vomiting, headache, visual and hearing difficulties, and a documented right-sided facial droop. He has just been seen by his family physician who wrote a referral note asking the hospital to rule out a brain lesion or stroke. He has already been seen earlier the same day at another emergency department with the same symptoms. The ER physician at the stroke centre takes a history, performs a physical exam (omitting the gait assessment), orders a CT scan, and considers stroke as a diagnosis. The CT does not show acute changes. The physician does not see the family doctor’s referral note. He does not consult the neurologist available at the designated stroke centre. He does not order a CT angiogram to image the cerebral vessels. He discharges the patient with a diagnosis of “Dizzy – Bell’s Palsy – Peripheral Vertigo.”

The patient returns to the same hospital by ambulance the next morning, deteriorating. He is intubated. Five days later, MRI confirms an acute infarct in the territory of the proximal basilar artery, and CT angiography confirms the stroke. The catastrophic outcome that timely intervention might have prevented is now permanent.

Hasan v Trillium Health Centre (Mississauga), 2024 ONCA 586, is the Court of Appeal for Ontario’s recent affirmance of a plaintiff trial judgment arising from this clinical sequence. The standard-of-care breach was not contested on appeal. The appeal was about causation — and specifically, about the defendant’s argument that the plaintiff was required to particularize what specific treatment would have been administered and prove its specific effectiveness, and that absent such specific evidence, causation could not be established.

The Court of Appeal rejected the defence position decisively. The case is doctrinally one of the most important plaintiff causation decisions in Ontario in 2024. It articulates the evidentiary gap doctrine cleanly: where the defendant’s negligence creates the very evidentiary uncertainty the defence wants to rely on, the gap supports an inference of causation in favour of the plaintiff. It applies the Snell v Farrell “robust and pragmatic” approach to causation that rejects any requirement of scientific proof. It articulates the “available treatments” framework that operates in delayed-diagnosis cases where specific treatment courses were foreclosed by the negligence. And it joins three other appellate cases in the rewritten cluster on this site as plaintiff affirmances, balancing the previously defence-heavy appellate jurisprudence in the library.

The clinical context: posterior circulation stroke and basilar artery occlusion

Strokes are catastrophic but often treatable events. The clinical framework for stroke care has evolved substantially over the past two decades, with time-critical thrombolytic and endovascular treatments now part of the standard of care in designated stroke centres.

Stroke types. Strokes are broadly categorized as ischemic (approximately 85%, caused by blockage of a cerebral vessel) or hemorrhagic (approximately 15%, caused by bleeding). Ischemic strokes are further subdivided by the vascular territory affected:

• Anterior circulation strokes (carotid artery territory) affect the cerebral hemispheres. The classic FAST symptoms apply: Face droop, Arm weakness, Speech difficulty, Time to call for help. These are the strokes the public has been educated about.
• Posterior circulation strokes (vertebrobasilar territory) affect the brainstem, cerebellum, occipital lobes, and thalami. Symptoms are often more subtle and easily misdiagnosed:
  • Dizziness or vertigo
  • Nausea and vomiting
  • Visual disturbance (double vision, visual field cuts, complete vision loss)
  • Hearing difficulty
  • Dysarthria (slurred speech)
  • Ataxia (gait instability and coordination problems)
  • Cranial nerve palsies, including facial weakness that can be mistaken for Bell’s palsy
  • Diminished consciousness in severe cases

The misattribution of posterior circulation symptoms to other diagnoses (vertigo, migraine, intoxication, anxiety, Bell’s palsy) is one of the most common patterns of stroke misdiagnosis. The challenge for ER physicians is to recognize the subtle and sometimes constellation-dependent features of posterior circulation stroke.

Basilar artery occlusion (BAO). The basilar artery is formed by the union of the two vertebral arteries and supplies the brainstem, cerebellum, and posterior cerebral hemispheres. Occlusion of the basilar artery is one of the most catastrophic forms of stroke:

• Untreated mortality is 80 to 90 percent
• Survivors often have devastating disability, including “locked-in” syndrome (intact cognition with near-total paralysis)
• Diagnosis requires high clinical suspicion combined with vessel imaging (CT angiogram or MR angiogram)
• Treatment options when diagnosed in time include thrombolysis and mechanical thrombectomy
• Time-to-treatment is determinative: earlier treatment produces dramatically better outcomes

Vertebral artery dissection. A tear in the arterial wall, often associated with neck movement, trauma, chiropractic manipulation, or sometimes occurring spontaneously. Dissection can produce stroke through two mechanisms:

• Thromboembolic mechanism: a clot forms at the dissection site and embolizes distally, occluding distal cerebral vessels including the basilar artery. This is the mechanism the trial judge found in Hasan.
• Perforator ischemia mechanism: the dissection directly compromises the small perforator arteries supplying the brainstem. This was the defence theory in Hasan, which the trial judge rejected.

Stroke treatment. Modern stroke care is fundamentally time-critical:

• IV thrombolysis (tPA): intravenous tissue plasminogen activator, effective within 4.5 hours of symptom onset for most patients, with extended windows in select cases
• Intra-arterial thrombolysis: tPA delivered via catheter directly to the clot
• Endovascular thrombectomy: catheter-based mechanical retrieval of the clot, effective up to 24 hours per Ontario Health requirements (April 2025), with shorter optimal windows
• Antiplatelet therapy: aspirin
• Anticoagulation: heparin in select cases

The phrase “time is brain” captures the time-critical character of stroke care. Each minute of delayed treatment correlates with measurable brain tissue loss. The standard of care for ER assessment of suspected stroke includes:

• Detection of FAST signs through history and exam
• Application of the NIH Stroke Scale (NIHSS) for severity grading
• Gait and cerebellar assessment, particularly for posterior circulation symptoms
• Non-contrast CT to exclude hemorrhage
• CT angiogram for vessel imaging when stroke is suspected
• Neurology consultation, particularly at designated stroke centres
• Initiation of treatment without delay where indicated

Ontario stroke care infrastructure. The province has a coordinated stroke care network of designated Regional Stroke Centres providing comprehensive care including endovascular thrombectomy. CorHealth Ontario, the previous coordinator, has been integrated into Ontario Health. Trillium Health Centre (Mississauga) is one of the designated Regional Stroke Centres. The clinical implication for Hasan: the patient presented at a facility specifically designed for stroke care, with neurology consultation and all three recanalization options available — and the ER physician chose not to engage any of them.

The substantive facts

December 3, 2011 — first ER visit (Milton District). The patient, then 40 years old, presented to Milton District Hospital with dizziness, nausea, and vomiting. The ER physician diagnosed probable peripheral vertigo, prescribed medication, and discharged him.

Same day — family physician. Later that morning, the patient saw his family physician. The family physician was sufficiently concerned to refer the patient directly to a stroke-equipped emergency department, with a written referral note specifically asking the hospital to rule out an organic cause (brain lesion or stroke).

Same day — Trillium ER (the appellant physician’s care). The patient presented to Trillium that afternoon. The Trillium ER nurses documented:

• The family doctor’s referral note
• The prior hospital visit with the same symptoms
• Headache, visual and hearing difficulties
• A “right side droop”

The appellant ER physician assessed the patient. The physician’s actions:

• Documented the patient’s symptoms and prior hospital visit
• Did not see or document the family doctor’s referral note
• Performed a physical examination
• Did not conduct a gait assessment
• Ordered medications, bloodwork, and a CT scan
• Considered stroke as a possible diagnosis
• Reviewed the CT, which did not show acute abnormalities
• Noted some symptom improvement
• Did not consult neurology (the designated stroke centre had stroke neurologists available)
• Did not order a CT angiogram (the imaging needed to assess cerebral vessels)
• Diagnosed: “Dizzy – Bell’s Palsy – Peripheral Vertigo”
• Discharged the patient with medication

December 4, 2011 — return by ambulance. The patient awoke with worsened symptoms and returned to Trillium by ambulance. The same physician assessed him at 9:15 AM and ordered another CT scan. The patient’s condition continued to deteriorate. At 11:45 AM — over two hours after the morning assessment — the physician consulted a neurologist. The patient required intubation. Care was handed over to an internist.

December 8, 2011 — diagnosis confirmed. Brain MRI showed an acute infarct and loss of normal blood flow in the proximal basilar artery. CT angiography confirmed the stroke. The catastrophic outcome was permanent.

The narrow appellate issue

The standard-of-care breach was not contested on appeal. The trial judge had found multiple SOC breaches in the appellant physician’s December 3 assessment — failure to see the family doctor’s referral note, failure to conduct a gait assessment, failure to consult neurology, failure to order CT angiography, missed differential diagnosis of stroke. The breaches were not disputed before the Court of Appeal.

The appeal was focused entirely on causation. The appellant’s argument:

• The plaintiff failed to prove what specific treatment would have been administered absent the breach
• The plaintiff failed to prove whether that specific treatment would have been successful
• A finding that “some form of treatment” would have been initiated was insufficient
• Without specific treatment identification and specific effectiveness proof, causation could not be established

The Court of Appeal rejected this argument decisively. The doctrinal framework that operated in the appellate analysis is the heart of the case.

The Sacks v Ross two-step causation framework

The trial judge had applied the two-step framework from Sacks v Ross, 2017 ONCA 773. The framework structures causation analysis in delayed-diagnosis cases:

Step 1: What likely happened? The factual question of what actually occurred — the diagnosis, the cause of harm, the natural history of the disease, the actual sequence of events.

Step 2: What would likely have happened absent the breach? The counterfactual question — what would the sequence have looked like if the defendant had met the standard of care?

The plaintiff prevails if both questions can be answered on the balance of probabilities and the answer to step 2 differs from the answer to step 1 in a way that establishes the breach caused the harm.

Step 1: What likely happened (the embolic stroke finding)

The trial judge found that the patient suffered an embolic stroke originating from a dissecting aneurysm in the left vertebral artery at the C5/C6 level. The mechanism: a clot formed at the dissection site and embolized distally to occlude the basilar artery, producing the catastrophic posterior circulation stroke.

The defence theory was perforator ischemia — that the dissection directly compromised the small perforator arteries supplying the brainstem, rather than producing a more proximal embolic occlusion. This distinction matters clinically because the treatments differ: an embolic basilar occlusion is amenable to thrombolysis and endovascular recanalization, while perforator ischemia from dissection is less directly amenable to those interventions.

The trial judge rejected the perforator ischemia theory and accepted the embolic stroke theory. The Court of Appeal found the trial judge’s reasoning “deeply rooted in the evidence” and “well laid out by careful reasons.” No palpable and overriding error.

The evidentiary gap doctrine

A critical feature of step 1 was the trial judge’s application of the evidentiary gap doctrine from Ghiassi v Singh, 2018 ONCA 764, and Goodwin v Olupona, 2013 ONCA 259. The doctrine, distilled:

• Where the defendant’s negligence prevents the plaintiff from demonstrating the causal link between the breach and the injury, the court can infer causation
• The onus shifts to the defendant to rebut the inference
• Any remaining uncertainty is resolved in favour of the plaintiff
• The alternative — permitting the defendant to rely on the evidentiary gap his own negligence created — would “effectively immunize” the negligent physician

In Hasan, the negligent failure to order timely vessel imaging (CT angiography) created an evidentiary gap. There was no imaging beyond the initial non-contrast CT showing the progression of the stroke. The defendant wanted to use this gap to argue that the plaintiff could not establish what specific treatments would have been administered or how they would have worked. The trial judge — correctly, per the Court of Appeal — refused to allow the defendant to benefit from the gap his own negligence created.

The doctrine has substantial implications well beyond stroke. Any malpractice case involving failure to investigate (failure to order imaging, failure to perform diagnostic tests, failure to obtain specialist consultation) potentially engages the doctrine. Where the failure produces an evidentiary gap that would otherwise defeat causation, the gap can support an inference in favour of the plaintiff. The doctrine prevents the perverse outcome of rewarding defendants for the depth of their evidentiary failures.

The Court of Appeal in Hasan expressly affirmed the trial judge’s application of Ghiassi and Goodwin. The appellate court rejected the appellant’s argument that the trial judge had “effectively created a presumption of causation” or “improperly relaxed the burden of proof on the plaintiff.” The framework operates not as a presumption but as a permitted inference. The plaintiff must still establish the factual foundations for the inference; once those foundations exist, the trier of fact may draw the inference of causation, and the defendant must rebut it.

Step 2: What would likely have happened absent the breach

The trial judge addressed the counterfactual analytically:

• The patient would have been assessed by a neurologist (Trillium had neurologists available on call)
• The patient would have received a timely CT angiogram (the imaging that would have shown the basilar artery occlusion)
• The patient would have received appropriate treatment from the available options

The plaintiff’s expert (Dr. Gladstone) testified that the available treatments included:

• Aspirin and heparin as first-line antiplatelet/anticoagulation therapy
• Recanalization as the most effective treatment, available in three forms:
  • IV tPA (intravenous thrombolysis)
  • Intra-arterial tPA (catheter-delivered thrombolysis)
  • Endovascular thrombectomy (mechanical clot retrieval via catheter)

All three recanalization options were available at Trillium at the time. The clinical decision about which to deploy would have been made by the treating neurologist based on the imaging, the timing, and the patient’s specific anatomy and presentation.

The “specific treatment particularization” rejection

The defendant’s central appellate argument was that the plaintiff was required to particularize which specific treatment would have been administered and prove its specific effectiveness. The trial judge had rejected this requirement, and the Court of Appeal affirmed.

The reasoning:

• Requiring the plaintiff to particularize the specific treatment that would have been deployed would be to “invite speculation”
• A neurologist would have made the treatment decision on the spot based on the imaging available at the time
• Dr. Gladstone explained that “it would be exceptionally difficult to foresee all the various treatment options and their associated intricacies in advance of the actual procedure”
• The “most significant takeaway” from the evidence was that various treatment options were available for the treating physicians to consider and deploy
• The evidentiary gap brought about by the lack of timely imaging — the result of the physician’s own negligence — made specific treatment particularization impossible

The framework that emerges from Hasan: in delayed-diagnosis cases where the negligence foreclosed the actual treatment course, the plaintiff need not particularize the specific treatment that would have been administered. It is enough to show that:

• The diagnosis would have been made in time
• Effective treatments were available
• Proper assessment would have led to deployment of an appropriate treatment
• That treatment would more likely than not have produced a better outcome

The plaintiff in Hasan established each element. Causation followed.

The outcome finding

The trial judge found that with proper treatment, the patient would have had successful recanalization and a good outcome. The finding rested on three considerations:

• The patient’s imaging and clinical presentation
• His unique anatomical features
• The medical literature on recanalization outcomes

The Court of Appeal accepted this finding. The trial judge had carefully addressed the evidence and applied the relevant legal framework. No palpable and overriding error.

The “scientific proof not required” framework

The Court of Appeal closed by observing that the trial judge’s findings “reflect faithfully the Supreme Court’s direction to trial judges to take a robust and pragmatic approach to determining whether the defendant’s negligence caused the plaintiff’s loss without requiring scientific proof of causation.”

This is the Snell v Farrell, [1990] 2 SCR 311, framework, reaffirmed and developed in Benhaim v St-Germain, 2016 SCC 48. The framework operates as follows:

• The plaintiff must prove causation on the balance of probabilities
• The trier of fact applies common sense and the totality of the evidence
• Scientific proof of the specific causal mechanism is not required
• Where the evidence permits an inference of causation, the trier of fact may draw it
• The defendant must produce evidence to rebut the inference, not merely speculation

The framework recognizes that medical causation is often genuinely uncertain at a scientific level. Requiring the plaintiff to prove the specific causal mechanism with scientific certainty would be to require the impossible in many cases. The “robust and pragmatic” approach permits the trier of fact to make causation findings based on the realistic state of the medical evidence.

Hasan applies the framework cleanly to a stroke malpractice case. The plaintiff need not prove the precise mechanism by which earlier diagnosis would have produced a better outcome with scientific certainty. The plaintiff needs to show — on the balance of probabilities, with the evidence available — that the breach more likely than not produced the catastrophic outcome.

The Lawson v Laferrière distinction

A doctrinal point the Court of Appeal touched on indirectly: the plaintiff must show that avoiding the unfavourable outcome was “more likely than not” — not merely that they would have had “a chance” of a better outcome.

This is the Lawson v Laferrière, [1991] 1 SCR 541, framework. The Supreme Court of Canada has rejected loss of chance as an independent head of damages in medical malpractice. The plaintiff cannot recover for the lost opportunity of a better outcome; the plaintiff must prove the better outcome itself was more likely than not absent the breach.

In Hasan, the trial judge applied this standard explicitly. The finding was not that the patient “might have had a better outcome” or “had a chance of a better outcome” — the finding was that the patient “would have had a successful recanalization and a good outcome.” This is the substantive causation finding Lawson requires.

The stroke malpractice cluster

Hasan v Trillium is the principal Ontario plaintiff anchor for stroke malpractice litigation in the rewritten case-comment cluster on this site. The stroke malpractice cluster now spans:

• Hasan v Trillium (Ontario appellate): plaintiff affirmance; basilar artery stroke; evidentiary gap doctrine; available treatments framework
• Sutherland v Booth (Ontario trial): plaintiff defeat; expert evidence collapsed under cross-examination
• Stroke Misdiagnosis in Ontario Emergency Rooms: patient guide on the clinical and legal framework
• Five Dangerous ER Misdiagnoses: master patient guide identifying stroke as one of the five
• Stroke Malpractice Lawyer in Toronto: practice page

Together these provide comprehensive coverage of stroke malpractice in Ontario — clinical context, legal frameworks for prosecution, plaintiff outcomes both successful and unsuccessful, and prospective client guidance.

The appellate cluster — eleven cases, four plaintiff affirmances

Hasan v Trillium is the eleventh case in the rewritten appellate cluster and the fourth clean appellate affirmance of a plaintiff trial victory:

• Willick v Willard (Ont CA): defendant affirmance
• Hanson-Tasker v Ewart (BC CA): defendant affirmance
• Dumesnil v Jacob (Manitoba CA): new trial after defendant judgment
• Penate v Martoglio (Ont CA): new trial after defendant judgment
• Rybakov v Khattak (BC CA): defendant affirmance
• Focken v Miller (BC CA): defendant affirmance
• Henry v Zaitlen (Ont CA): affirmance of plaintiff jury verdict; failure-to-investigate SOC
• Denman v Radovanovic (Ont CA): affirmance of plaintiff bench-trial liability; cumulative risks + team responsibility
• Rogerson v Grey Bruce (Ont CA): defendant affirmance; mandatory reporting + multi-step causation
• Hemmings v Peng (Ont CA): affirmance of plaintiff $12M; causation by elimination + AFE rejection
• Hasan v Trillium (Ont CA): affirmance of plaintiff trial victory; evidentiary gap + scientific proof not required

Seven defendant-favourable dispositions against four plaintiff affirmances. The appellate cluster is now substantively comprehensive and substantially balanced. Together the eleven cases cover the full doctrinal terrain of Canadian appellate malpractice practice — expert evidence, causation in delayed diagnosis, informed consent, jury procedure, adequacy of reasons, mandatory reporting, anaesthetic complications, and stroke malpractice.

The plaintiff wins sub-grouping — five cases

Hasan v Trillium is the fifth plaintiff win in the rewritten cluster:

• Kotorashvili v Lee (Ontario, trial): $35,000 — orthopaedic surgery
• Henry v Zaitlen (Ontario, trial + appellate): ~$1.5 million — failure to investigate spinal cord fistula
• Denman v Radovanovic (Ontario, trial + appellate): $8.5 million — informed consent for multi-step AVM treatment
• Hemmings v Peng (Ontario, trial + appellate): $12 million — anaesthetic accident during caesarean section
• Hasan v Trillium (Ontario, trial + appellate): substantial damages — stroke malpractice; evidentiary gap doctrine

The five cases span specialty areas (orthopaedics, neurology, interventional neuroradiology, obstetric anaesthesia, emergency medicine/stroke), damages calibrations (from $35,000 to $12 million+), and doctrinal frameworks (treatment plan deviation, failure to investigate, informed consent, conjunctive breaches, evidentiary gap). Together they illustrate the realistic range of plaintiff outcomes when the facts and the evidence align.

Doctrinal lessons

The case stands for several propositions.

Defendants cannot rely on evidentiary gaps their own negligence created. Where the breach prevents the plaintiff from demonstrating the causal link with greater specificity, the gap supports an inference of causation in favour of the plaintiff. The onus shifts to the defendant to rebut. Uncertainty is resolved in the plaintiff’s favour.

Scientific proof of causation is not required. The plaintiff need not prove the specific causal mechanism with scientific certainty. The trier of fact applies common sense and the totality of the evidence under a “robust and pragmatic” approach.

Specific treatment particularization is not required in delayed-diagnosis cases. Where the negligence foreclosed the actual treatment course, the plaintiff need not particularize the specific treatment that would have been administered. It is enough to show effective treatments were available and proper assessment would have led to deployment of an appropriate one.

The two-step Sacks v Ross framework structures causation analysis. What likely happened? What would likely have happened absent the breach? Both answered on the balance of probabilities.

The Lawson v Laferrière standard requires “more likely than not,” not “a chance of.” Canadian common law does not recognize loss of chance as an independent head of damages. The plaintiff must clear the balance of probabilities threshold on outcome causation.

Stroke care is time-critical. The standard of care for ER assessment of suspected stroke includes FAST signs, NIHSS, gait/cerebellar assessment, vessel imaging (CT angiogram), neurology consultation, and prompt treatment. At a designated Regional Stroke Centre with neurology available and all three recanalization options, the failure to engage the available resources is a breach.

Posterior circulation strokes are commonly misdiagnosed. Dizziness, vertigo, vomiting, visual disturbance, and facial droop in posterior circulation stroke can be misattributed to peripheral vertigo, migraine, intoxication, anxiety, or Bell’s palsy. ER assessment requires high clinical suspicion combined with structured neurological examination.

Appellate review of plaintiff verdicts is substantially deferential. The Housen v Nikolaisen palpable and overriding error standard applies symmetrically. Plaintiff verdicts supported by careful trial reasoning will be affirmed.

Why this case matters

For prospective clients considering stroke malpractice claims. Hasan illustrates the realistic possibility of plaintiff success in stroke missed-diagnosis cases — particularly where:

• The patient presented at a designated stroke centre with neurology available
• The clinical features should have triggered stroke assessment
• The physician failed to engage the available stroke care resources (vessel imaging, neurology consultation)
• The negligence created an evidentiary gap that the defendant later wanted to rely on
• Effective treatments were available and would have produced a better outcome

For more on the realistic evaluation of stroke malpractice claims, see Stroke Misdiagnosis in Ontario Emergency Rooms: What Patients Need to Know and Suing for Medical Malpractice in Ontario: What You Need to Know.

For plaintiff counsel. Hasan is essential precedent on several fronts:

• The evidentiary gap doctrine cleanly articulated in a current appellate authority
• The “available treatments” causation framework for delayed-diagnosis cases
• The rejection of specific treatment particularization requirements
• The Snell v Farrell “robust and pragmatic” framework in modern application
• The Lawson v Laferrière “more likely than not” threshold

For cases involving failure to investigate, failure to order diagnostic imaging, or failure to obtain specialist consultation, Hasan provides the doctrinal framework for surviving the defendant’s “you can’t prove what would have happened” arguments.

For defence counsel. Hasan establishes the limits of the “you can’t prove what would have happened” defence. Where the defendant’s own negligence created the evidentiary uncertainty being relied upon, the defence will face the Goodwin/Ghiassi immunization concern. Defence strategy in delayed-diagnosis cases should engage the substantive question of available treatments and likely outcomes rather than resting on evidentiary gap arguments.

For practising ER physicians and other front-line clinicians assessing possible stroke. The case provides clear professional lessons:

• Read all referral notes received with the patient — particularly notes from referring physicians flagging specific differential concerns
• Perform structured neurological examination including gait assessment for any patient with potential CNS symptoms
• Maintain low threshold for stroke assessment in patients with posterior circulation symptoms (dizziness, vomiting, visual changes, hearing changes, ataxia, cranial nerve palsies)
• Order vessel imaging (CT angiogram) when stroke is in the differential and standard CT is negative
• Consult neurology at designated stroke centres where stroke is being considered
• Recognize the misdiagnosis pattern of attributing posterior circulation stroke symptoms to peripheral vertigo or Bell’s palsy
• Document clinical reasoning when stroke is considered and not pursued

For more on related Ontario stroke and missed-diagnosis jurisprudence, see Sutherland v Booth (stroke causation defeat at trial), Henry v Zaitlen (failure-to-investigate plaintiff affirmance), and Stroke Malpractice Lawyer in Toronto (practice area information).

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Decision Date: July 25, 2024

Jurisdiction: Court of Appeal for Ontario

Citation: Hasan v Trillium Health Centre (Mississauga), 2024 ONCA 586 (CanLII)

Outcome: Plaintiff trial judgment affirmed. Appeal dismissed.

Key authorities: Snell v Farrell, [1990] 2 SCR 311 (robust and pragmatic causation; no scientific proof required); Lawson v Laferrière, [1991] 1 SCR 541 (loss of chance rejection; more likely than not threshold); Clements v Clements, 2012 SCC 32 (but-for causation framework); Benhaim v St-Germain, 2016 SCC 48 (adverse inference framework); Sacks v Ross, 2017 ONCA 773 (two-step causation analysis); Goodwin v Olupona, 2013 ONCA 259 (evidentiary gap doctrine); Ghiassi v Singh, 2018 ONCA 764 (evidentiary gap doctrine); Housen v Nikolaisen, 2002 SCC 33 (appellate standard of review)