When a patient is presented with a recommended treatment option, they are always then next asked for their agreement with, and their consent to, the proffered medical procedure. It is the legal duty of the relevant health care worker to provide the patient with enough information about the procedure and its material risks to enable that patient to then make an “informed consent” to proceed.

Even where consent is given, the medical procedure may (without there being any fault in its execution by the health care worker) cause an injury to the patient which they did not anticipate or expect. Where such an injury is significant and debilitating, an action may be brought whereby the patient, now the plaintiff, will seek compensatory damages. The basis of the action would be an alleged failure to disclose the risk of the injury which became a consequence of the treatment undertaken.

This is not a Battery

It is now clearly established that this cause of action in such cases is founded in negligence and not battery. A battery is committed where there is no consent at all to the procedure, or where the procedure goes beyond the consent given.

The Burden of Proof

The plaintiff bears the onus to prove, on a balance of probabilities, that not only was there was a material non-disclosure of the relevant risk, but also that had they been so advised, that they would have refused their consent and declined to undergo the medical procedure. The latter is known as proving causation.


If we assume that a material nondisclosure is proven, and a serious injury occurred, it is axiomatic that the plaintiff will give evidence that they would not have undertaken the procedure. If they say the opposite there would be no cause of action as the non-disclosure would necessarily have had no causative effect to the injury occurring.

Subjective Test

Such evidence, if accepted at face value, would mean that causation would always be proven. Such a subjective approach is not, therefore, the law in Canada.

Objective Test

On the other end of the spectrum is a solely objective test which asks the question “what would a reasonable person in the patient’s position have decided had they been informed of all the material risks”? Although this standard has been declared preferable by many – it avoids a patient’s bitterness and regrets in hindsight – it does create its own dilemma.

If a health care worker, given their expertise, recommends the procedure to a patient after evaluating their condition, can causation ever be proven? What reasonable person would say no in such circumstances? Does that not in itself dismiss an objective test?

Balanced Test

The Supreme Court of Canada dealt with this dilemma, which it considered to be res integra (i.e. a novel point of law) in 1980 in its decision in Reibl v Hughes. There the court rejected a hybrid approach and in the end preferred an objective test with some modification in the following words:

I think it is the safer course on the issue of causation to consider objectively how far the balance in the risks of surgery or no surgery is in favour of undergoing surgery. The failure of proper disclosure pros and cons becomes therefore very material and so too are any special considerations affecting the particular patient.

Special Considerations

This is how the plaintiff’s subjective evidence is admitted and becomes relevant. The evidence that might be given would concern questions that were asked of the health care worker and the answers that were given. In addition, events and circumstances in the patients life which reasonably affect the decision to proceed would be relevant. It allows into evidence, to be assessed objectively, those special considerations which can then be considered in deciding the causation issue.

As the court said:

The patient’s particular situation and the degree to which the risks of surgery or no surgery are balanced would reduce the force, on an objective appraisal, of the surgeon’s recommendation. Admittedly, if the risk of foregoing the surgery would be considerably graver to a patient than the risks attendant upon it, the objective standard would favour exoneration of the surgeon who has not made the required disclosure. Since liability rests only in negligence, in a failure to disclose material risks, the issue of causation would be in the patient’s hands on a subjective test, and would, if his evidence was accepted, result inevitably In liability unless, of course, there was a finding that there was no breach of the duty of disclosure. In my view, therefore, the objective standard is the preferable one on the issue of causation.

At Wise Health Law, we focus on health and administrative law. With more than 30 years of combined health law and litigation experience, we help regulated health professionals and national and provincial regulated health professional associations to find solutions to their legal and regulatory issues. With offices in both Toronto and Oakville, Ontario we are easily accessible. Contact us online, or at 416-915-4234 for a consultation.


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