Choosing a Substitute Decision-Maker (SDM)

Topic Overview

What is a substitute decision-maker?

A substitute decision-maker (SDM) is a person you choose in advance to make health care decisions for you in the event that you can't make them for yourself. An SDM can help make health care decisions on your behalf at the end of life or anytime you can't make these decisions for yourself, such as if you are severely injured. An SDM also may be called a health care representative, agent, or proxy.

In general, an SDM can agree to or refuse treatment and can withdraw treatment on your behalf. Your SDM can use the information in your advance care plan (also called an advance directive, personal directive, or living will), statements made by you in the past, and what he or she knows about you personally to make these decisions. For example, your SDM can consent to surgery, refuse to have you placed on life-support machines, or request that you be taken off life support.

How do I choose a substitute decision-maker?

Choose someone you trust. Your SDM needs to be willing and able to make potentially difficult treatment decisions for you. Discuss your desires, values, fears, and preferences about health care in various situations. The more your SDM knows about you and your values, the more likely he or she will be able to make the kinds of decisions that you would make if you were able.

How do I appoint a substitute decision-maker?

The legal document that grants this decision-making power to the person you select may be called a representation agreement, a personal or proxy directive, or another name depending on your province or territory. In general, the laws on appointing a substitute decision-maker vary from province to province.

An SDM can usually make treatment decisions (if your health professionals agree with these decisions) at the end of life or anytime you can't make these decisions for yourself. If the SDM is someone you appointed on a representation agreement, the agreement must specify that you want the SDM to make end-of-life decisions for you. Once you select an SDM, it is important to thoroughly discuss your health care preferences with him or her, such as when to continue or abandon life-support measures, and to document these preferences.

Because the laws on substitute decision-makers vary from province to province, it is best if you see an attorney who is experienced in helping people appoint SDMs. Your doctor may also be familiar with the SDM laws in your province and what is required to have someone legally appointed. For more information on choosing a substitute decision-maker in your province, visit


Current as of: December 9, 2019

Author: Healthwise Staff
Medical Review: Anne C. Poinier, MD - Internal Medicine
E. Gregory Thompson, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Kathleen Romito, MD - Family Medicine
Shelly R. Garone, MD - Palliative Medicine
Robin L. Fainsinger, MB, ChB, LMCC, CCFP - Palliative Medicine
Jean S. Kutner, MD, MSPH - Geriatric Medicine, Palliative Medicine

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