Section 1101 Of Chapter 1. Evidence Of Character, Habit, Or Custom From California Evidence Code >> Division 9. >> Chapter 1.

. (a) Except as provided in this section and in Sections 1102, 1103, 1108, and 1109, evidence of a person's character or a trait of his or her character (whether in the form of an opinion, evidence of reputation, or evidence of specific instances of his or her conduct) is inadmissible when offered to prove his or her conduct on a specified occasion.
  (b) Nothing in this section prohibits the admission of evidence that a person committed a crime, civil wrong, or other act when relevant to prove some fact (such as motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake or accident, or whether a defendant in a prosecution for an unlawful sexual act or attempted unlawful sexual act did not reasonably and in good faith believe that the victim consented) other than his or her disposition to commit such an act.
  (c) Nothing in this section affects the admissibility of evidence offered to support or attack the credibility of a witness.