No minor issue: the mature minor doctrine and its legal implications

Age is just a number, until it isn’t. In personal injury law, the age of a patient can determine whether a refusal of medical treatment is legally valid, who bears liability, and whether a damages award shrinks because a plaintiff didn’t do enough to help themselves.

In this article, we’ll discuss the mature minor doctrine, which for personal injury lawyers, injured minors, and concerned parents, is a material principle to understand.

What is the mature minor doctrine in Canada?

The mature minor doctrine is a common law rule that says a person under the age of majority can consent or refuse medical treatment on their own. The caveat under this doctrine is that the minor should have enough maturity and understanding to make that decision.

As such, it is not about how old someone is. Rather, it is about whether the minor genuinely grasp what is being proposed, what the risks are, and what happens if they either say yes or no.

The doctrine’s core logic is that once a young person demonstrates enough understanding and independence of judgment, their right to decide about their own body is recognised by law. This right is granted with or even without parental involvement.

Case law roots of the mature minor doctrine

The doctrine has its roots in the 1985 United Kingdom House of Lords decision in Gillick v. West Norfolk and Wisbech Area Health Authority, [1985] 3 All ER 402. In that case, it was held that parental authority over a child’s medical decisions does not disappear at a fixed age. Instead, it diminishes gradually as the child’s maturity increases.

Canadian courts have adopted this reasoning, and the Supreme Court of Canada formally endorsed it in A.C. v. Manitoba (Director of Child and Family Services), 2009 SCC 30. This case is still the leading authority when it comes to the mature minor doctrine.

Watch this video to learn more about when can a court override a mature minor’s medical decision:

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What “mature” means in the mature minor doctrine

There is no checklist, no age cutoff, and no single test on what constitutes as “mature” under the doctrine. In A.C. v. Manitoba, the Supreme Court set out factors that courts use to assess whether a minor is genuinely mature:

• the nature and risks of the proposed treatment
• whether the young person can understand the information and appreciate the consequences
• whether their views are stable and genuinely their own, and not just reflecting parental pressure
• family relationships, social environment, and other influences on independent thinking
• any psychiatric or emotional vulnerabilities
• whether the illness itself may be impairing their judgment

The more serious the decision, the more closely the court examines each of these factors.

How do courts assess a minor’s capacity to consent?

Capacity here means more than being able to repeat back what a doctor said. Per the Canadian Medical Protective Association (CMPA), a minor demonstrates capacity to consent when they can:

• understand the nature and purpose of the proposed treatment,
• appreciate the expected benefits and risks, understand what refusing means, and
• make that choice free of coercion

That last point matters more than it might seem. The Supreme Court in A.C. v. Manitoba recognised that younger adolescents are more susceptible to parental and peer influence than older ones. This is part of why the law applies more scrutiny to minors under 16 than those 16 and over, at least in Manitoba.

The “sliding scale of scrutiny”

The court in A.C. v. Manitoba also described the test as a “sliding scale of scrutiny.” The principle is as follows:

• the more mature the minor, the more weight courts give to their wishes
• the more serious the decision, i.e., particularly where refusal could mean death or permanent harm, the more rigorously courts should examine if maturity does exist
• if a court is satisfied that a minor’s decision reflects genuine, independent, informed judgment, their wishes “ought to be respected”

When the minor’s refusal can or cannot be upheld

In practice, Canadian courts have never upheld a minor’s refusal of treatment if doing so would almost certainly result in death, unless the treatment was unlikely to succeed.

In Re A.Y. (1993), 111 Nfld. & P.E.I.R. 91, a 15-year-old Jehovah’s Witness with terminal cancer was found to be mature and not “in need of protection” because the proposed blood transfusion was not medically essential given his prognosis. In citing Re A.Y., the court in A.C. v. Manitoba said that “[w]hether a child is in need of protection requires a case-by-case analysis…”

How capacity rules differ across provinces

Capacity rules are not uniform across Canada, since each province has its own laws to be considered:

• Ontario: there is no age floor, and all persons, including minors, are presumed capable under its Health Care Consent Act (HCCA)
• British Columbia: under the Infants Act, minors may consent if they have capacity and the healthcare provider has made reasonable efforts to confirm the treatment is in the minor’s best interests
• Manitoba: those under 16 are presumed not to have capacity, but that presumption can be rebutted; this is the framework confirmed in A.C. v. Manitoba
• Quebec: the age of consent is generally 14 under the Civil Code of Quebec; parental consent still applies when care is not medically necessary and could cause serious and permanent effects
• Alberta, Saskatchewan, Nova Scotia, Newfoundland and Labrador: no stipulated statutory age of consent to medical treatment; the mature minor doctrine under common law governs, though courts in Alberta generally recognise 16 as a practical threshold

Here’s a video that explains the rights of children in general under Canadian law, aside from the mature minor doctrine:

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Can a minor’s refusal count as failure to mitigate?

Given the legal risks of mature minor doctrine, a minor-plaintiff must take reasonable steps to reduce their losses, including undergoing treatment a reasonable person in their position would accept.

If a minor-plaintiff refuses recommended treatment, the defendant may argue that the plaintiff failed to mitigate and that damages should be reduced accordingly. The mature minor doctrine complicates that argument, and in either direction.

If the minor’s refusal was competent

Where a minor’s refusal was the product of a genuinely mature, informed, independent decision, that refusal may be legally valid.

In Malette v. Shulman, 72 OR (2d) 417, still cited by A.C. v. Manitoba, the Ontario Court of Appeal confirmed that a competent person’s right to refuse treatment survives even when refusal may result in death. That principle does not disappear just because the patient is young.

If the minor’s refusal was competent, it is harder for a defendant to argue that declining the treatment was unreasonable. The question is not whether treatment was recommended; it is whether, given everything, a competent person in the minor’s position would be expected to accept it.

If the minor’s refusal was not competent

Where the minor lacked the capacity to make a valid refusal, the analysis shifts, since an incompetent refusal is not a legally effective refusal.

Two questions then arise:

• whether parents, guardians, or a court should have intervened, and
• whether the failure to do so contributed to the plaintiff’s continued harm

That may affect both the quantum of damages and the apportionment of responsibility among parties in a given case.

When does refusing to treat a minor create liability?

Healthcare providers face a genuine dilemma when a minor refuses treatment. If they treat a minor without a valid consent, they can be exposed to battery liability. On the other hand, if they accept the refusal without proper assessment, their risk to negligence liability increases, especially if the minor was not capable in refusing the treatment.

As suggested by the CMPA, thorough capacity assessments and well-documented consent discussions are the primary protection for healthcare providers facing complaints or civil claims. The assessment must be done on a case-by-case basis, and it cannot be replaced by a general assumption based on the patient’s age.

Battery vs. Negligence

In these cases, there are two distinct liabilities that may apply:

• battery: for treating a capable minor without their consent; in Malette, the physician was found liable for transfusing an unconscious adult Jehovah’s Witness who carried a signed card refusing blood, even though the transfusion saved her life
• negligence: for failing to treat the concerned minor, or accepting an incompetent minor’s refusal as though it were valid, when proper assessment would have revealed that the minor lacked the necessary capacity

What providers must document

As per guidance issued by the CMPA, which also works as a mutual medical defence organization, a solid medical record should capture the following:

• that the provider assessed the minor’s capacity for the specific decision at issue
• what the minor was told about the treatment, its risks, its benefits, and the consequences of refusing
• that the decision appeared voluntary and free of pressure
• any steps taken to involve parents or guardians, and whether the minor consented to that involvement

A provider who simply defers to a minor’s refusal without working through this process takes a meaningful legal risk, particularly in cases where the stakes are high and a competent parent would otherwise be making the call.

Mature minor doctrine: a major issue for lawyers and healthcare providers

The mature minor doctrine has been part of Canadian law for decades, and A.C. v. Manitoba made its constitutional foundations clear. What it did not resolve is the case-by-case complexity that personal injury lawyers should look at every time a minor plaintiff’s treatment choices become a live issue.

Whether a refusal was competent, whether the right people were consulted, whether a provider’s documentation holds up under scrutiny, none of that answers itself. Age may just be a number, but in everyday situations, it is a number that can move the outcome of a case.

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