Does the presumption of sanity apply at the sentencing phase of a criminal trial?

Defendant cites no authority--and we have found none--for the proposition that the presumption of sanity ends at conviction and has no application at the sentencing phase of a criminal trial. In California, insanity cannot be proved at the trial on the issue of guilt. The defense is raised by a separate plea and decided in a separate trial. (See 1026, subd. (a).) Defendant did not place his sanity at issue; as a result, at the guilt trial he was "conclusively presumed" sane, and evidence tending to prove insanity was inadmissible. (People v. Wells (1949) 33 Cal.2d 330, 350, 202 P.2d 53.)

[801 P.2d 335]

Page 92