Section 16. In those instances that a health care proxy has not been executed, nothing herein shall preclude a health care provider from relying upon the informed consent of responsible parties on behalf of incompetent or incapacitated patients to the extent permitted by law.

Nothing in this chapter shall invalidate a power of attorney delegating the authority to make health care decisions executed prior to the enactment of this chapter.

A competent adult’s failure to appoint a health care agent or to provide the agent with specific health care instructions pursuant to this article shall create no presumptions regarding the adult’s wishes about health care.