Cal. HSC § 11362.79

This article does not authorize a qualified patient or person with an identification card to engage in the smoking of medicinal cannabis under any of the following circumstances: (a) In a place where smoking is prohibited by law. (b) In or within 1,000 feet of the grounds of a school, recreation center, or youth center, unless the medicinal use occurs within a residence. (c) On a schoolbus. (d) While in a motor vehicle that is being operated. (e) While operating a boat.