If you become incapacitated, who will make your medical decisions? A health care proxy allows you to appoint someone else to act as your agent for medical decisions. It will ensure that your medical treatment instructions are carried out, and it is especially important to have a health care proxy if you and your family may disagree about treatment. Without a health care proxy, your doctor may be required to provide you with medical treatment that you would have refused if you were able to do so.