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 Wisconsin, a living will is known as a 'Declaration to Physicians' or 'Wisconsin Living Will' and is governed by Chapter 154 of the Wisconsin Statutes. This legal document allows an individual, known as the declarant, to express their wishes regarding the use or non-use of life-sustaining procedures and feeding tubes if they become incapacitated and are in a terminal condition or persistent vegetative state. The living will only becomes effective when the individual is no longer able to participate in their health care decisions. Wisconsin law also recognizes Power of Attorney for Health Care, which allows an individual to appoint an agent to make health care decisions on their behalf if they become incapacitated. Additionally, Wisconsin has provisions for Do Not Resuscitate (DNR) orders, which instruct health care providers not to perform CPR if a patient's breathing or heart stops. These documents are part of the state's advance directives laws, which enable individuals to plan for their medical treatment and end-of-life care.