What is the current test for sanity of a criminal defendant?

2 At the time the offenses were committed, the sanity of a criminal defendant was measured by whether he lacked "substantial capacity either to appreciate the criminality ... of his conduct or to conform his conduct to the requirements of law." (People v. Drew (1978) 22 Cal.3d 333, 345, 149 Cal.Rptr. 275, 583 P.2d 1318.) Section 25, subdivision (b), added by initiative three days later, provides that sanity is now determined by whether a defendant "was incapable of knowing or understanding the nature and quality of his or her act and of distinguishing right from wrong at the time of the commission of the offense."