Adults Who Can't Make Medical Decisions on Their Own


Adults can usually make medical decisions (consent to treatment) on their own. But they may need someone to make medical decisions for them if their decision-making ability is affected by an illness or disability. This is called substituted consent.

Deciding Whether Someone Can Make Medical Decisions

When suggesting treatment, medical professionals must evaluate whether their patients are able to make medical decisions. In law, this is called the capacity to consent.

Having a mental illness or disability doesn’t automatically mean a person can’t make their own medical decisions. Even a person under tutorship or for whom a protection mandate has been homologated may be able to make certain medical decisions on their own. Also, refusing treatment that could be beneficial doesn’t necessarily mean someone can’t make medical decisions on their own.

When deciding whether a patient can make medical decisions, the doctor must evaluate whether the patient can understand these things:

  • the nature of his illness
  • the nature and purpose of the treatment
  • the advantages and risks of the treatment
  • the risks of not having the treatment

Also, the patient’s illness must not affect his capacity to consent. If these criteria are met, the patient can consent to treatment on his own. Of course, patients who are unconscious can’t consent to treatment.

Patients’ ability to make medical decisions can change over time. For example, patients with dementia may be able to make medical decisions one day but not the next because their condition fluctuates. Doctors must therefore evaluate patient’s capacity to consent on an ongoing basis.

Patients may be able to make some medical decisions but not others. For example, someone may be able to consent to a common procedure like a blood test, but not to a more complex procedure like an organ transplant.

Who Makes Decisions for Adults Who Can’t Consent?

Planning Ahead

People can express their wishes in advance in case they become unable to make medical decisions. For example, people can create advance medical directives.

If a patient becomes unable to make medical decisions and the patient has advance medical directives, the doctor must follow the instructions in the directives.

Who Can Provide Substituted Consent?

If the patient doesn’t have advance medical directives, these people can consent for the patient:

  • the patient’s legal representative (mandatary or tutor), if there is one
  • if there is no legal representative, the patient’s married or civil-union spouse, or common-law partner
  • if there is no spouse or partner, or if the spouse or partner can’t give consent, the patient’s close relative or someone concerned for the patient, like a close friend

Respecting the Patient’s Best Interests

The person consenting for the patient must act in the patient’s best interests. The benefits of the treatment must be greater than the risks involved.

The person must also take the patient’s wishes into account. Patients might have made their wishes known ahead of time, for example through a living will or a protection mandate.

The Court 

In some situations, the court must make medical decisions for patients who can’t consent on their own. The court’s permission is needed in these cases:

  • it’s impossible to get someone else to consent for the patient
  • the person who can give substituted consent refuses to consent for no good reason
  • the patient clearly refuses care required for their health

Exception: The court’s permission isn’t needed to give emergency or hygienic care to a person who can’t consent on their own. Health care professionals can provide this care even if the patient refuses.