Here is the scenario, an officer stops you for a traffic violation and subsequently sees evidence of possession of a legal amount of marijuana. Can they proceed to search your car on that basis? No, the law allows for possession of recreational marijuana and prohibits police from conducting exploratory searches on that basis alone. Specially, H&S § 11362.1(c) clearly provides that marijuana possessed under lawful circumstances is “not contraband nor subject to seizure,” nor does a subject’s lawful conduct pursuant to section 11362.1(a) “constitute the basis for detention, search, or arrest.” Also, People v. Torres et al. (2012) 205 Cal.App.4th 989, 993-998, held that a warrantless search upon the speculative belief that more marijuana than lawfully allowed may be found is illegal.
There are instances where a police officer may be justified in detaining you however. H&S § 11362.3(a) makes it illegal (an infraction) to smoke or ingest marijuana (1) in a public place (subd. (a)(1), which arguably includes in a vehicle while out on the public streets or in any other public place), (2) anywhere where smoking tobacco is prohibited (subd. (a)(2)), (3) within 1,000 feet (including simple possession, whether or not it’s being smoked, if on the grounds) of a school, day care center, or youth center while children are present (subd. (a)(3) & (5)), or (4) while driving or operating, or when riding in the passenger seat or compartment, of a motor vehicle, boat, vessel, or aircraft (subd. (a)(7) & (8)). It is also illegal for anyone to (5) possess (whether or not it’s being smoked) an open container or open package of marijuana while driving, operating, or riding in the passenger seat of a motor vehicle, boat, vessel, or aircraft. (Subd. (a)(4)).
Based on the foregoing, As long as you are over 21, there are no open containers inside the vehicle and you are not smoking the pot inside the car, there would be no legal basis to conduct a search of the vehicle for more marijuana.