California Code, Penal Code - PEN § 29.2

(a) The intent or intention is manifested by the circumstances connected with the offense.

(b) In the guilt phase of a criminal action or a juvenile adjudication hearing, evidence that the accused lacked the capacity or ability to control his or her conduct for any reason shall not be admissible on the issue of whether the accused actually had any mental state with respect to the commission of any crime. This subdivision is not applicable to Section 26.