California Code, Vehicle Code - VEH § 28071

Every passenger vehicle registered in this state shall be equipped with a front bumper and with a rear bumper. As used in this section, “bumper” means any device designed and intended by a manufacturer to prevent the front or rear of the body of the vehicle from coming into contact with any other motor vehicle. This section shall not apply to any passenger vehicle that is required to be equipped with an energy absorption system pursuant to either state or federal law, or to any passenger vehicle which was not equipped with a front or rear bumper, or both, at the time that it was first sold and registered under the laws of this or any other state or foreign jurisdiction.