Final answer:
A nurse must respect and uphold a do-not-resuscitate order as per the patient's advance directive, legally binding them to withhold resuscitation if the patient's heart stops or they stop breathing.
Step-by-step explanation:
When a nurse is caring for a patient with a do-not-resuscitate (DNR) order, their legal obligation is to respect the patient's wishes and not to initiate resuscitation efforts. This means that if the patient's heart stops or they stop breathing, medical personnel, including nurses, are legally bound to withhold resuscitative measures according to the patient's advance directive. A DNR is typically a part of a living will, which is a critical component in end-of-life care, reflecting the patient's autonomy and their right to decline unwanted medical treatment. The nurse's role is not to convince the patient to change their decision or to ignore the order, even if they personally disagree with it.