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 Maine, a living will is referred to as an Advance Health Care Directive (AHCD). The AHCD allows an individual, known as the principal, to outline their preferences for medical treatment in the event that they are unable to communicate their wishes due to incapacity. This document can include instructions on the administration, withholding, or withdrawal of life-sustaining treatment if the individual is in a terminal condition or in a state of permanent unconsciousness. Maine's statutes provide the legal framework for creating an AHCD, ensuring that the individual's health care decisions are respected even when they cannot participate in the decision-making process. The relevant laws can be found in the Maine Revised Statutes, specifically under Title 18-C, Article 5, Part 8, which deals with health care advance directives. Additionally, Maine law allows for the creation of Do Not Resuscitate orders (DNRs), which are separate directives that inform medical personnel not to perform cardiopulmonary resuscitation (CPR) if the individual's heart stops beating or they stop breathing.