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 Washington State, a living will is known as an Advance Directive. Washington law allows individuals to create an Advance Directive to inform health care providers of their wishes regarding medical treatment if they become unable to communicate due to a serious health condition. The Advance Directive can include instructions on the administration, withholding, or withdrawal of life-sustaining treatment if the individual is in a terminal condition or is permanently unconscious. The relevant statutes are found in the Washington Revised Code (RCW) under Title 70, particularly in chapters 70.122 and 70.245. These laws outline the requirements for creating a valid Advance Directive, including the need for it to be in writing, dated, and signed by the declarant in the presence of two witnesses. The document may also be notarized. Additionally, Washington recognizes Physician Orders for Life-Sustaining Treatment (POLST), which are medical orders that address a patient's preferences for life-sustaining treatments and are designed for those with serious illnesses or frailty.