(a) Nothing in this chapter shall impair or supersede any legal right or legal responsibility which any person may have to effect the withholding or withdrawal of cardiopulmonary resuscitation in any lawful manner or affect the validity of orders not to resuscitate issued and implemented under other circumstances. In such respect, the provisions of this chapter are cumulative.

(b) Nothing in this chapter shall be construed to preclude a court of competent jurisdiction from approving the issuance of an order not to resuscitate under circumstances other than those under which such an order may be issued pursuant to this chapter.