In People v. Yarber (1979) 90 Cal.App.3d 895, a man was found guilty by jury of 18 counts of oral copulation with a minor, and his wife was found guilty of one count, apparently as an aider and abettor. Her conduct, on that occasion, consisted of an act of oral copulation with her husband, which was followed by acts of oral copulation between her husband and two of the minors. The jury was instructed, in accordance with CALJIC No. 3.01, that a person aids and abets the commission of a crime "if, with knowledge of the unlawful purpose of the perpetrator of the crime, he aids, promotes, encourages or instigates by act or advice the commission of such crime." The court held that the jury should have been instructed that a person aids and abets the commission of a crime "if, with knowledge of the unlawful purpose of the perpetrator, he intentionally aids, promotes, encourages or instigates by act or advice the commission of such crime," and that instructing the jury in terms which omitted the intention element was, on the facts of that case, prejudicial error. (90 Cal.App.3d at pp. 916-917.) The court in Yarber reasoned: "Intent is what must be proved; from a person's action with knowledge of the purpose of the perpetrator of a crime, his intent to aid the perpetrator can be inferred. In the absence of evidence to the contrary, the intent may be regarded as established. But where a contrary inference is reasonable -- where there is room for doubt that a person intended to aid a perpetrator -- his knowledge of the perpetrator's purpose will not suffice." ( Id., at p. 916.) "On the peculiar facts of this case," the court concluded, "it is reasonably probable that the jury found the wife guilty because they believed that her act had encouraged one of the minors to engage in the sex act with her husband and because she had knowledge of her husband's purpose, without regard to whether she intended that her act would have such effect. Instructing the jury in terms which omitted the intention element was therefore prejudicial error as to her." ( Id., at pp. 916-917.) The Court found this particular instruction defective because it failed to require a finding that the defendant intended to aid the perpetrator in the commission of the crime. "Intent is what must be proved; from a person's action with knowledge of the purpose of the perpetrator of a crime, his intent to aid the perpetrator can be inferred. In the absence of evidence to the contrary, the intent may be regarded as established. But where a contrary inference is reasonable -- where there is room for doubt that a person intended to aid a perpetrator -- his knowledge of the perpetrator's purpose will not suffice." ( Id., at p. 916.) In People v. Yarber (1979) a husband and wife were charged with sexual offenses involving five teenage girls. The husband was found guilty of 18 counts of oral copulation with a minor; the wife of 1 count thereof, based on the theory she had aided and abetted her husband in his performance of the act with a minor, by virtue of having herself first orally copulated him in the minor's presence. The conclusion reached there respecting the aiding and abetting instruction however, was arrived at because the evidence was such that an inference could not be drawn the wife intended to aid her perpetrator husband simply because she had knowledge of his purpose to have the minor orally copulate him. Thus it was observed that: "The Ellhamer/Ott synthesis that intent is inferred from the knowledge by the aider and abettor of the perpetrator's purpose is sound, generally, as a matter of human experience, but we cannot extrapolate therefrom, as a matter of law, that the inference must be drawn. Intent is what must be proved ; from a person's action with knowledge of the purpose of the perpetrator of a crime, his intent to aid the perpetrator can be inferred ." ( People v. Yarber (1979) 90 Cal.App.3d 895, 916 153 Cal. Rptr. 875.) It was likewise pointed out, however, that "In the absence of evidence to the contrary, the intent may be regarded as established ." ( Id. , at p. 916.) It was contended that court-appointed psychiatrists should be directed by the court to concern themselves with amenability to treatment other than in a state hospital. The court disposed of this contention as follows: ". Although the better practice may be for the court to direct the appointed experts to state an opinion as to whether an offender could benefit from treatment in a facility other than a state hospital, it does not necessarily follow that the offender has a procedural right that the court do so." ( Id., at p. 904.)