California Evidence Code Section 801 - Interpretation
Evidence Code section 801 provides that expert opinion testimony is admissible if the opinion is:
(1) "related to a subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact;" and;
(2) based on matter that "reasonably may be relied upon by an expert in forming an opinion" on the subject.
In People v. Brown (2004) 33 Cal.4th 892, the Supreme Court held that if the evidence is admissible under Evidence Code section 801, it need not also be admissible under Evidence Code section 1107. (Id. at pp. 907-908.)
Evidence Code section 1107 makes evidence of "intimate partner battering and its effects" admissible if such evidence is relevant.
The Supreme Court had stated prior to People v. Brown, supra, that BWS describes women who have been abused "over an extended period of time." (People v. Romero (1994) 8 Cal.4th 728, 735, fn. 1.)
Thus, in People v. Gomez (1999) 72 Cal.App.4th 405, 417, disapproved by People v. Brown, supra, the court held that a "single violent incident . . . is not sufficient to establish that a woman suffers from battered women's syndrome."
However, Evidence Code section 801 requires no prior incidents of abuse.