What is a health care proxy? A health care proxy is also known as a medical power of attorney. It is a legal document in which designate an agent to make health care decisions for you. It is closely related to your living will (also called medical directive) in which you state your health care preferences. The agent appointed in your health proxy is the person who carries out those wishes when you cannot do so. This video explains what the document is, how to use it, and why most pre-printed and internet forms are lacking.