Interpretation of California Evidence Code Section 1101
In People v. Ewoldt (1994) 7 Cal.4th 380, the California Supreme Court interpreted Evidence Code section 1101 and explained the different theories justifying admissibility of prior acts evidence under that section:
"This distinction, between the use of evidence of uncharged acts to establish the existence of a common design or plan as opposed to the use of such evidence to prove intent or identity, is subtle but significant. Evidence of intent is admissible to prove that, if the defendant committed the act alleged, he or she did so with the intent that comprises an element of the charged offense. 'In proving intent, the act is conceded or assumed; what is sought is the state of mind that accompanied it.' . . . ."
Ewoldt used a shoplifting prosecution as an example: evidence that defendant committed similar acts could be admitted to show he (1) meant to steal rather than inadvertently failed to pay, conceding or assuming he took the goods without paying (intent/absence of mistake or accident); (2) actually took the goods without paying, conceding or assuming he was at the scene but not that he took the goods (common plan); and/or (3) committed the theft, conceding or assuming that someone did so but not that he was at the scene (identity). (Ibid.)
The court then addressed the degree of similarity to the charged crime required to permit admission of other acts evidence introduced to show intent.
"The least degree of similarity (between the uncharged act and the charged offense) is required in order to prove intent. . . . In order to be admissible to prove intent, the uncharged misconduct must be sufficiently similar to support the inference that the defendant '" probably harbored the same intent in each instance." ' " (Id. at p. 402.)
A greater degree of similarity is required to prove the existence of a common design or plan. "To establish the existence of a common design or plan, the common features must indicate the existence of a plan rather than a series of similar spontaneous acts, but the plan thus revealed need not be distinctive or unusual. . . . Unlike evidence of uncharged acts used to prove identity, the plan need not be unusual or distinctive; it need only exist to support the inference that the defendant employed that plan in committing the charged offense. " (Ewoldt, supra, 7 Cal.4th at p. 403.)
The greatest degree of similarity is required to show relevance to prove identity. The uncharged misconduct and the charged offense must "share common features that are sufficiently distinctive so as to support the inference that the same person committed both acts," and "the pattern and characteristics of the crimes must be so unusual and distinctive as to be like a signature." (Ewoldt, supra, 7 Cal.4th at p. 403.)
Ewoldt further explained that even if Evidence Code section 1101 does not require exclusion of the evidence of defendant's uncharged misconduct because it is relevant to prove a material fact other than his criminal disposition, the court still must consider whether the evidence is more prejudicial than probative pursuant to Evidence Code section 352. (Ewoldt, supra, 7 Cal.4th at p. 404.)