Your advance directives become legally valid as soon as you sign them in front of the required witnesses. However, they normally do not go into effect unless you are unable to make your own decisions and each state establishes its own guidelines for when advance directives become operative. The rules may differ for living wills and medical powers of attorney, as described below.
Living will. In most states, before your living will can guide medical decision making, two physicians must certify that you are unable to make medical decisions and that you are in the medical condition specified in the state's living will law (such as "terminal illness" or "permanent unconsciousness"). Other requirements also may apply, depending upon the state.
Medical power of attorney. Most medical powers of attorney go into effect when your physician concludes that you are unable to make your own medical decisions. If you regain the ability to make decisions, your agent cannot continue to act for you. Many states have additional requirements that apply only to decisions about life-sustaining medical treatments. For example, before your agent can refuse a life-sustaining treatment on your behalf, a second physician may have to confirm your doctor's assessment that you are incapable of making treatment decisions.
Your state specific advance directive provided by The National Hospice and Palliative Care Organization explains when the documents go into effect under your state's laws.
Will my advance directives be honored if I am in an accident or experience a medical crisis at home and emergency technicians are called?
In these emergency situations, unless you are able to speak for yourself, your consent to treatment is presumed. Once emergency personnel have been called, they are obligated to do what is necessary to stabilize a patient for transfer to a hospital, both from accident sites and from a home or other facility. After a physician fully evaluates the person's condition and determines the underlying conditions, advance directives can be implemented if warranted.
Emergency medical technicians cannot honor living wills or medical powers of attorney. However, in many localities, the specific crisis of cardiac arrest/respiratory arrest is addressed by a document called a "Non-hospital Do-Not-Resuscitate Order." Individuals with underlying conditions that would make resuscitation unwarranted under any circumstances can carry a special "do-not-resuscitate" (DNR) order signed by a doctor and in some states can wear a special bracelet or other indicator that such a signed order exists.