California Code, Business and Professions Code - BPC § 22435.1

The provisions of Section 22435.2 shall apply when a shopping cart or a laundry cart has a sign permanently affixed to it that identifies the owner of the cart or the retailer, or both;  notifies the public of the procedure to be utilized for authorized removal of the cart from the premises;  notifies the public that the unauthorized removal of the cart from the premises or parking area of the retail establishment, or the unauthorized possession of the cart, is a violation of state law;  and lists a valid telephone number or address for returning the cart removed from the premises or parking area to the owner or retailer.