Cal. Veh. Code § 22517 : CALIFORNIA VEHICLE CODE — RULES OF THE ROAD — STOPPING, STANDING, AND PARKING — Opening vehicle door on side available to moving traffic

No person shall open the door of a vehicle on the side available to moving traffic unless it is reasonably safe to do so and can be done without interfering with the movement of such traffic, nor shall any person leave a door open on the side of a vehicle available to moving traffic for a period of time longer than necessary to load or unload passengers.