Some states combine these two into one form. It normally becomes effective when you are no longer capable of expressing your wishes and have been diagnosed as terminally ill, irreversibly unconscious, or in a persistent vegetative state.
Most states have statutes recognizing living wills.
With a health-care power of attorney, you appoint an agent to make medical decisions for you if you are unable to express your wishes. Some states place restrictions on who may serve as an agent. You should discuss the provisions of your health-care power of attorney with your agent before you sign the document and you should be sure that the person you appoint as your agent will be able and willing to make decisions that will affect your life and death. Usually a living will is limited to your wishes about life-sustaining treatment under the conditions set down by state statute. No, and you cannot be denied admission to a hospital or nursing home if you don't have one.