This legal document differs from the above in that instead of naming another person to make decisions, it specifically authorizes doctors to discontinue medical care under certain circumstances. For example, it may direct a doctor to cease life-prolonging medical treatment when the patient is unable to participate in the decision and is terminally ill, permanently unconscious, or severely brain damaged. If your parents have a durable medical power of attorney or a health care proxy, but also have a living will, the living will provides written instructions for the individual they have designated to make decisions. An attorney can assist in preparing a living will.