In medical malpractice law, the doctrine of informed consent rests on a simple proposition: a patient cannot meaningfully consent to a medical procedure unless they understand the nature of the procedure, its material risks, and the alternatives, including the alternative of doing nothing. Where a physician fails to provide that disclosure, and where the patient (or a reasonable person in the patient’s circumstances) would not have consented to the procedure if properly informed, the physician has breached the duty.
Denman v Radovanovic is a leading recent Ontario decision on informed consent. The trial judgment, 2023 ONSC 1160, was released on February 16, 2023. The trial judge found three defendant physicians liable for a failure to obtain informed consent for a multi-step elective treatment of an arteriovenous malformation (AVM) in the brain. Damages had been agreed at $8.5 million. The trial judge later awarded $3 million in costs in 2023 ONSC 3621. The Court of Appeal for Ontario dismissed the defendants’ appeal on April 16, 2024 in 2024 ONCA 276, upholding both the liability finding and the costs award.
The case is doctrinally important on two fronts. First, it confirms and clarifies the duty to obtain informed consent in the context of multi-step elective treatments, particularly where the risks of the proposed treatment are weighed against the natural history of an asymptomatic underlying condition. Second, it establishes that the duty extends to all advising physicians on a multi-disciplinary team, not only to the physician performing the procedure.
Background: AVMs and the decision whether to treat
An arteriovenous malformation is a tangle of abnormal blood vessels in which arteries connect directly to veins without the normal capillary network in between. AVMs in the brain carry a risk of spontaneous bleeding, which can be catastrophic. The Spetzler-Martin grading system rates AVMs from I to V based on size, location, and venous drainage; higher grades correspond to higher procedural risk if treatment is attempted.
The decision whether to treat an unruptured, asymptomatic AVM is a difficult one, because the risks of intervention must be weighed against the natural history risk of the AVM bleeding spontaneously over time. Treatment options include embolization (where the abnormal vessels are blocked), stereotactic radiosurgery, microsurgical resection, or some combination of these. The published literature, including the ARUBA trial, has generated significant debate about whether intervention or conservative management is preferable for unruptured AVMs of various grades.
For a patient with a higher-grade AVM, the procedural risks are substantial. Where the patient is asymptomatic, the case for accepting those risks depends entirely on a careful comparison of the procedural risk against the natural history risk, communicated honestly and accurately to the patient.
The facts
Mr. Denman’s medical history began in May 2010, when he suffered a stroke or seizure and was found to have an AVM and a flow-related aneurysm in his brain. The aneurysm was treated and resolved. The AVM was not.
In March 2011, he underwent stereotactic radiosurgery aimed at resolving the AVM. That treatment was unsuccessful; the AVM remained.
In 2014, the case was discussed at a multidisciplinary case conference at Toronto Western Hospital attended by the three defendant physicians: Dr. Ivan Radovanovic (a neurosurgeon), Dr. Karel ter Brugge (a diagnostic radiologist), and Dr. Vitor Mendes Pereira (a neuroradiologist and neurosurgeon). The team developed a multi-step treatment plan involving a series of embolization procedures followed by a possible microsurgical resection. The plan was elective; Mr. Denman was, at the time, asymptomatic. His AVM was unruptured and graded Spetzler-Martin Grade IV.
The first embolization, in 2014, only partially embolized the AVM. A second embolization, also partial, was performed later. The third procedure, on June 23, 2015, combined an embolization and a microsurgical resection. During that third procedure, Mr. Denman, then 54 years old, suffered a catastrophic brain bleed. He was left with a severe traumatic brain injury and significant permanent disability.
The Denmans sued the three physicians on the multidisciplinary team. The claim was framed as a failure of informed consent. The plaintiffs did not allege that the procedure itself was performed negligently. The allegation was that they had not been given the information they needed to meaningfully consent to it.
The doctrine of informed consent
The Supreme Court of Canada set out the modern framework for informed consent in Reibl v Hughes, [1980] 2 SCR 880. The key elements are:
- A physician has a duty, without being asked, to disclose to the patient the material risks of a proposed procedure, its gravity, and any special or unusual risks, including risks with a low probability of occurrence
- A patient has the right to make a meaningful decision based on a full understanding of those risks
- Where the duty is breached, causation is established by a “modified objective test”: the question is whether a reasonable person in the patient’s circumstances would have consented to the procedure if properly informed
The test is “modified objective” because it considers a reasonable person, but a reasonable person who shares the patient’s particular circumstances, values, and concerns. It is not a purely subjective test (which would invite hindsight reasoning) and not a purely objective test (which would ignore the patient’s actual situation).
In informed consent cases involving elective procedures on asymptomatic conditions, the analysis often turns on whether a reasonable person in the patient’s circumstances, having understood the procedural risks and the natural history risks accurately, would have proceeded. The question is rarely “would the patient have consented to anything,” but rather “would the patient have consented to this procedure, in this multi-step plan, at this time, with this team.”
The trial decision
The trial judge, Justice Ferguson, found that all three defendant physicians had failed to obtain Mr. Denman’s informed consent. The findings included:
- Dr. ter Brugge advised Mr. Denman of the risks associated with a single embolization but failed to inform him of the risks of no treatment and the likelihood of requiring further treatments
- An informed consent discussion did not occur at all before the second embolization
- For the third combined procedure, there was conflicting evidence about what risks were communicated. Mrs. Denman testified that the team had described the combined procedure as carrying a 2% risk of serious complications, with no treatment carrying a 4% annual risk compounding over time. Other evidence in the case suggested the actual procedural risk was higher (roughly 3 to 5%) and the no-treatment risk was lower than represented. The trial judge accepted Mrs. Denman’s evidence as a credible account of what she had been told
The trial judge found that the patient had been “misled” about the scope, efficacy, risk, and need for the medical interventions. Applying the modified objective test under Reibl, she found that neither Mr. Denman nor a reasonable patient in his circumstances would have proceeded with the treatment plan if accurately informed. The Denman family was entirely successful at trial. Damages, agreed at $8.5 million, were entered against the three defendants.
The Court of Appeal: the duty in multi-disciplinary teams
The defendants appealed. The Court of Appeal, per Justice Rouleau, dismissed the appeal in its entirety. The Court of Appeal’s most significant doctrinal contribution was on the question of which physicians on a multi-disciplinary team carry the duty of informed consent.
The traditional understanding has been that the duty rests primarily on the physician performing the procedure. Denman clarifies that, in the multi-disciplinary context, the duty extends to all physicians who advise the patient on the proposed treatment, not only to the one who picks up the instruments. Where a team plans the patient’s treatment together, each physician who counsels the patient on the plan carries some part of the duty to ensure the patient is properly informed.
This is a significant clarification. In modern medicine, complex treatment is increasingly provided by multidisciplinary teams. Patients are often counselled by several physicians before consenting, each contributing different expertise and a different piece of the conversation. The Court of Appeal’s reasoning makes clear that responsibility for informed consent does not collapse onto a single physician simply because that physician performs the procedure. Each advising physician has a role in ensuring the patient understands what is being proposed and what the alternatives are.
The Court of Appeal also affirmed the trial judge’s application of the Reibl modified objective test and found no error in her credibility findings. The appeal on liability was dismissed. Leave to appeal the costs award was refused.
The $3 million costs award
The $3 million costs award is itself notable. Applying the factors in Rule 57.01 of the Rules of Civil Procedure, the trial judge identified the following considerations as supporting a substantial award:
- The case had required experienced counsel; all three plaintiff lawyers were certified specialists in civil litigation
- The defendants were represented by the Canadian Medical Protective Association, a sophisticated litigant well aware of the cost of complex litigation and trials
- The costs sought represented approximately 29 to 32 percent of the agreed damages of $8.5 million
- The plaintiffs were entirely successful
- The case was complex
- The case was important to the Denman family
- Mrs. Denman was found to be a credible witness; the defendants’ evidence was found not to be credible or reliable
- The defendants had made last-minute disclosure and production
A $3 million costs award against defendant physicians is unusually large in the Ontario medical malpractice landscape. Denman will likely be cited in future costs arguments where complex multi-week trials produce successful outcomes against well-resourced defendants represented by the CMPA.
The doctrinal context
Denman is now the leading recent Ontario authority on informed consent in elective neurosurgical procedures and on the scope of the duty in multi-disciplinary care. It applies the Reibl framework to a fact pattern that is increasingly common: a multi-step elective treatment of an asymptomatic condition, planned by a team of subspecialists, where the procedural risks must be weighed against the natural history risks of the underlying disease.
The case stands for several propositions:
- The duty of informed consent applies with particular force to elective procedures on asymptomatic conditions, where the patient’s choice to accept procedural risk depends on a full and accurate understanding of the alternative of doing nothing
- The duty extends to all physicians who advise the patient as part of a multi-disciplinary team, not only to the physician performing the procedure
- Misleading the patient about the scope, efficacy, risk, or need for an intervention is a breach of the duty, even where the procedure itself is performed competently
- Costs in complex medical malpractice trials can be substantial, particularly where the defendants are represented by sophisticated, well-resourced counsel and where the litigation conduct (such as last-minute disclosure) compounds the cost burden on the plaintiff
Why this case matters
For plaintiffs and their counsel. Denman is now the leading recent authority for informed consent claims in Ontario, particularly those involving elective procedures and multi-disciplinary teams. The case confirms the Reibl modified objective test, clarifies the scope of the duty in team contexts, and provides authority for substantial costs awards against unsuccessful defendants. Counsel evaluating informed consent cases should pay particular attention to: what was communicated about the natural history of the underlying condition, whether the comparative risks of treatment versus no treatment were honestly presented, and whether each physician on the treating team contributed appropriately to the consent discussion.
For defence counsel and CMPA. The case is a significant statement about the duty of informed consent. Defence counsel reviewing files involving elective procedures should consider whether the consent process can be defended on the documentary record, particularly with respect to risks of no treatment and the likelihood of further interventions. The Court of Appeal’s clarification that the duty extends to all advising physicians on a multi-disciplinary team has practical implications for the assessment of liability across multiple defendants in complex cases.
For physicians on multi-disciplinary teams. Denman is a clear instruction that the duty of informed consent rests on every physician who counsels the patient about a proposed treatment, not only on the physician performing the procedure. The duty includes accurate disclosure of material risks, the risks of no treatment, and the likelihood of further interventions. In the context of multi-step elective treatments of asymptomatic conditions, the duty includes a particularly careful presentation of the comparative risk analysis, because that is the analysis on which the patient’s decision genuinely turns.
For more on surgical malpractice claims in Ontario, see the Surgical Errors practice page. For an overview of the legal process for medical malpractice claims in Ontario, see Suing for Medical Malpractice in Ontario: What You Need to Know.
Trial Decision: Denman v Radovanovic, 2023 ONSC 1160 (CanLII) (February 16, 2023, Justice Ferguson)
Costs Decision: Denman v Radovanovic, 2023 ONSC 3621 (CanLII) (June 15, 2023)
Appeal Decision: Denman v Radovanovic, 2024 ONCA 276 (CanLII) (Court of Appeal for Ontario, April 16, 2024, per Rouleau JA)
