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 Pennsylvania, a living will is legally recognized under the state's Advance Health Care Directive laws. These laws allow an individual, known as the declarant, to outline their preferences for medical treatment in the event that they are unable to communicate their wishes due to a medical emergency. The living will can include instructions to provide, withhold, or withdraw life-sustaining treatment if the declarant is in a terminal condition or permanently unconscious. Pennsylvania's Advance Health Care Directive also allows for the appointment of a health care agent to make decisions on behalf of the declarant if they are incapacitated. The relevant statutes can be found in the Pennsylvania Consolidated Statutes, Title 20, Chapters 54 and 56, which cover health care agents and representatives, living wills, and out-of-hospital do-not-resuscitate orders. It is important for individuals to comply with the specific requirements set forth in these statutes to ensure that their living will is legally enforceable.