An advance directive (sometimes referred to as a "living will") is a legal mechanism which enables individuals to plan for their own incapacity, and specifically for the situation where decisions have to be taken with respect to their health care after they are no longer mentally capable of making (or communicating) these decisions personally. Studies have shown that many Canadians fear that when they reach the end stages of life they may be subjected to overly aggressive and inappropriate forms of medical intervention, when they may no longer be capable of expressing their wishes. An advance directive enables individuals, while still mentally competent, to indicate what their wishes are concerning future health, and also to indicate whom they want to make decisions on their behalf. This person is sometimes referred to as the health care "proxy" or "agent." For example, a husband might decide to sign an advance directive which appoints his wife as his health-care proxy. This means that if the husband ever became mentally incapable of making his own health-care decisions, his wife would step in and have the legal right to make these decisions on his behalf.
The advance directive might also contain instructions which would guide the health care proxy in making these substitute decisions (eg, "If I am ever in a persistent vegetative state, I do not wish to be kept alive by artificial means, including artificial nutrition and hydration"). In making proxy decisions on behalf of a mentally incapable patient, the goal is to replicate the decision which the patient, if competent, would have made. Thus, instructions and guidance contained in an advance directive, as well as the proxy's knowledge of the patient's wishes, values and beliefs, are very important in arriving at an appropriate decision.
The legal validity of advance directives is now quite clear. Many provinces have recently enacted legislation which gives legal force and effect to these documents. Even in those parts of Canada where there is no legislation, the common law (that is, the nonstatutory law developed by judges) is now clear that an advance directive containing the patient's instructions is legally valid, and that these instructions (if they are unambiguous and relevant) must be followed.