§ 1101. Evidence of character to prove conduct
(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.
© Nothing in this section affects the admissibility of evidence offered to support or attack the credibility of a witness.
§ 1108. Evidence of another sexual offense
(a) In a criminal action in which the defendant is accused of a sexual offense, evidence of the defendant's commission of another sexual offense or offenses is not made inadmissible by Section 1101, if the evidence is not inadmissible pursuant to Section 352.
This section allows the admission of character evidence to prove a defendant's disposition to commit the charged sex offense. The legislative history to this section indicates it was intended to relax the evidence rules in sex offense cases by allowing the jury to be made aware of the defendant's other sex offenses in evaluating the accuser's and defendant's credibility.
Evidence Section 352 is a safeguard against the excessive prejudice that may result from the admission of defendant's other offenses.
§ 352. Discretion of court to exclude evidence
The court in its discretion may exclude evidence if its probative value is substantially outweighed by the probability that its admission will (a) necessitate undue consumption of time or (b) create substantial danger of undue prejudice, of confusing the issues, or of misleading the jury.
So how will the Judge decide whether to admit the 1993 accuser's testimony? There was no crime charged in that case, nor any admission by Michael Jackson that he engaged in the misconduct. Here are a couple of California cases on the topic:
People v Soto (1998, 5th Dist) 64 Cal App 4th 966, 75 Cal Rptr 2d 605.
In a prosecution under Pen C § 288(a), where the defendant was charged with a sexual offense against his minor niece, the trial court properly admitted evidence of the defendant's prior sexual conduct with other young female relatives pursuant to Ev C §§ 1108 and 352. Although the incidents occurred several years before the charged offense and did not involve similar conduct as with the charged offenses, Ev C § 1108 permits the introduction of such propensity evidence in sexual molestation cases. Further, the passage of a substantial length of time does not automatically render the prior incidents prejudicial. Thus, the propensity evidence was extremely probative of the defendant's sexual misconduct when left alone with young female relatives, and was exactly the type of evidence contemplated by the enactment of Ev C § 108. The prejudice presented by this evidence was the type inherent in all propensity evidence and did not render the evidence inadmissible.
But in this case, can we be certain Michael Jackson committed a crime in 1993? See, People v Pierce (2002, 2nd Dist) 104 Cal App 4th 893, 128 Cal Rptr 2d 397.
Before admitting propensity evidence of a prior sex offense, the court must engage in a careful weighing process under Ev C § 352. It must consider factors including relevance, similarity to the charged offense, the certainty of commission, remoteness, and the likelihood of distracting or inflaming the jury.
I call it 3 - 2 against admission of the evidence. There is relevance and similarity, but there is no certainty, it is remote and it is sure to distract or inflame the jury.
You can read Jackson's lawyer's response to the motion (redacted)
here. (pdf).