Which document allows a person to refuse or consent to medical treatment in advance?

The document that allows a person to refuse or consent to medical treatment in advance is a living will. A living will is a legal document that outlines an individual's preferences regarding medical treatment in situations where they may be unable to communicate their wishes due to severe illness or incapacitation. This document provides specific instructions about what types of medical interventions the individual does or does not want, thereby ensuring that their healthcare preferences are respected even if they cannot voice them at that moment.

In contrast, a power of attorney typically grants another individual the authority to make various decisions on behalf of someone else, which may include financial and legal decisions but does not specifically focus on medical treatment preferences. A contingent power of attorney is similar but would only take effect upon certain conditions, further diluting the immediacy of medical decisions. An advanced care directive is a broader term that may encompass a living will as well as other types of advance healthcare planning documents, but the most direct and specific document for medical treatment wishes remains the living will.