False. Every state recognizes both the proxy and living will type advance directives, although the laws of each state vary considerably in terminology, the scope of decision-making addressed, restrictions, and the formalities required for making an advance directive.
A more frequently raised question is whether an advance directive written in one state will be recognized in other states. In other words, is the directive portable across state lines. Many states expressly recognize out-of-state advance directives if the directive meets either the legal requirements of the state where executed or the state where the treatment decision arises. Several states are silent on this question. If there is doubt, the rules of the state where treatment takes place, not the state where the advance directive was signed, will normally control. However, even if an advance directive fails to meet technicalities of state law, health providers still should value the directive as important, if not controlling, evidence of the patient's wishes.
The threshold problem with most state provisions addressing portability is that they presumably require providers to be fully knowledgeable of the other state's law. Most use language derived from the Uniform Probate Code and similar to the following provision included in the now defunct Uniform Rights of the Terminally Ill Act:
A declaration executed in another state in compliance with the law of that state or of this
State is validly executed for purposes of this [Act].
Colorado and Utah offer a more user-friendly approach to
recognizing out-of state directives:
Unless otherwise provided therein, any medical power of attorney or
similar instrument executed in another state shall be presumed to
comply with the provisions of this [Act] and may, in good faith, be
relied upon by a health care provider or health care facility in
this state.