In Most states, a Living Will allows you to state your wishes as to whether or not you wish to receive life-sustaining treatment if you are terminally ill or permanently unconscious with no detectable brain activity. A Health Care Proxy and Durable Power of Attorney, on the other hand, allow you to appoint a trustworthy adult to make medical decisions for you if at any time in your life if you become temporarily incapacitated or unconscious due to an illness, accident or age.

In some states, the living will and the power of attorney for health care are combined into a single form (as is the case in California). In other state, you need both a Living Will and a Durable Power Of Attorney for Health Care (or Health Care Proxy).

In California, The Advance Health Care Directive replaces both the Living Will and Durable Power Of Attorney for Health Care; it is the legally recognized format for both a Living Will and a Durable Power Of Attorney for Health Care. Basically it combines the two into one form. Like a Living Will, California's Advanced Heath Care Directive allows you to state your wishes to accept or deny life saving treatments (all or some) that will only prolong your life if you are terminally ill or permanently unconscious. Like the Durable Power Of Attorney for Health Care, California's Advance Health Care Directive also allows you to appoint a health care agent to make medical decisions for you if you become temporarily unable to do so yourself (incapacitated or unconscious due to accident or injury or age). The Advanced Health Care Directive also enables you to give the agent instructions that detail the type of care you want (or don't want) if you become incapacitated.