A living will—also known as an Advance Health Care Directive—is a document in which the declarant or principal (person making the living will) specifies what kind of medical treatment the declarant does and does not want if the declarant has a medical emergency and is unable to communicate those wishes. A living will may direct health care providers to administer, withhold, or withdraw life-sustaining treatments if the declarant is in a terminal or irreversible condition.

Laws and terminology for documents related to living wills, Advance Health Care Directives, Do Not Resuscitate orders (DNRs), and other health care documents vary from state to state. These laws are generally located in a state’s statutes—often in the probate code or estates code.

In Oregon, a living will is known as an Advance Directive for Health Care. Oregon law allows individuals to express their wishes regarding medical treatment through this legal document in case they become incapable of communicating their decisions due to a medical emergency. The Advance Directive enables a person to appoint a health care representative to make decisions on their behalf and to specify preferences for life-sustaining treatment if they are in a terminal condition or permanently unconscious. The document can include instructions on the use of feeding tubes, mechanical ventilation, and other life-sustaining procedures. Oregon's statutes require the Advance Directive to be signed by the declarant and two witnesses. It is important to note that Do Not Resuscitate (DNR) orders are separate documents that instruct medical personnel not to perform CPR if a person's breathing or heartbeat stops. These legal instruments are governed by Oregon Revised Statutes, specifically under ORS Chapter 127 - Powers of Attorney; Advance Directives for Health Care; Death with Dignity.