California Code, Health and Safety Code - HSC § 43200

(a) The state board may adopt a regulation to prohibit the sale and registration in this state of a new motor vehicle certified by the state board to which there has not been securely and conspicuously affixed on a side window to the rear of the driver or, if it cannot be so placed, to the windshield of the motor vehicle in accordance with paragraph (3) of subdivision (b) of Section 26708 of the Vehicle Code, by the manufacturer a label on which the manufacturer shall endorse clearly, distinctly, and legibly true and correct entries disclosing the following information concerning the motor vehicle:

(b) A regulation may be adopted pursuant to this section only if the state board finds that the regulation is necessary for either of the following:

(c) Nothing in this division or in any other statute shall be construed as prohibiting a purchaser from removing the decal required by this section, after the purchaser has taken possession of the vehicle.