(a) By Reputation or Opinion.
When evidence of a person's character or character trait is admissible, it may be proved by testimony about the person's reputation or by testimony in the form of an opinion. On cross-examination of the character witness, the court may allow an inquiry into relevant specific instances of the person's conduct. If, in a criminal case, a defendant provides reasonable pretrial notice that the defendant intends to offer character evidence, the prosecution must provide the defendant with any relevant specific instances of conduct that the prosecution may use on cross-examination.
(b) By Specific Instances of Conduct.
When a person's character or character trait is an essential element of a charge, claim, or defense, the character or trait may also be proved by relevant specific instances of the person's conduct.