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 Ohio, a living will is a legal document that allows an individual to state their wishes regarding medical treatment in the event they are unable to communicate due to a serious medical condition. It is part of Ohio's Advance Directives laws, which are found in Chapters 2133 and 2135 of the Ohio Revised Code. The living will becomes effective when the individual is determined to be in a terminal condition or a permanently unconscious state by two physicians. The document can include instructions on the use of life-sustaining treatment, including resuscitation, mechanical ventilation, and artificial nutrition and hydration. Ohio law also recognizes Do Not Resuscitate (DNR) orders, which are separate from living wills and instruct medical personnel not to perform CPR if the individual's heart stops or if they stop breathing. It's important for individuals to ensure that their living wills and other advance directives are properly executed according to Ohio law to be legally binding.