A Durable Medical Power of Attorney, also called a medical or health care proxy, is a legal document that designates an agent to make medical decisions on your behalf. Your agent can be given authority to make medical decisions for you immediately (upon the signing of the document) or in the event that you are determined to be incapacitated (by a licensed physician). Either way, the powers delegated to your agent in your Durable Medical Power of Attorney do not terminate upon you becoming disabled or incapacitated.