Accomplice Liability In California Case Law
The idea that accomplice liability is derivative in nature means simply that "an accomplice is not guilty of an independent offense of 'aiding and abetting'; instead, he derives his liability from the primary party with whom he has associated himself.
The primary party's acts become his acts." (Dressler, Understanding Criminal Law (2d ed. 1995) 30.02[A], p. 428, fns. omitted.) As with criminal responsibility in general, accomplice liability involves both an actus reus and a mens rea.
Regarding the latter, "an aider and abettor . . . must 'act with knowledge of the criminal purpose of the perpetrator and with an intent or purpose either of committing, or of encouraging or facilitating commission of, the offense. '" (People v. Mendoza (1998) 18 Cal. 4th 1114, 1123, 959 P.2d 735, original italics. )
"When the offense charged is a specific intent crime, the accomplice must 'share the specific intent of the perpetrator'; this occurs when the accomplice 'knows the full extent of the perpetrator's criminal purpose and gives aid or encouragement with the intent or purpose of facilitating the perpetrator's commission of the crime.'" (People v. Prettyman (1996) 14 Cal. 4th 248, 259, 926 P.2d 1013.)
Under normal circumstances, an accomplice cannot be convicted of an offense where the perpetrator is acquitted in the same proceeding. It logically follows that an accomplice cannot be convicted of an offense in the same proceeding in which the perpetrator is convicted of a lesser included offense.
This is because conviction of a lesser included offense implies acquittal of the greater offense. (See People v. Kurtzman (1988) 46 Cal. 3d 322, 324-325, 331-334, 250 Cal. Rptr. 244, 758 P.2d 572.)