26:2H-59. Conditions under which advance directive becomes operative
7. a. An advance directive becomes operative when (1) it is transmitted to the attending physician or to the health care institution, and (2) it is determined pursuant to section 8 of this act that the patient lacks capacity to make a particular health care decision.

b. Treatment decisions pursuant to an advance directive shall not be made and implemented until there has been a reasonable opportunity to establish, and where appropriate confirm, a reliable diagnosis and prognosis for the patient.