California Code, Business and Professions Code - BPC § 21609.5

(a) Except as provided in subdivision (b), no junk dealer or recycler may purchase or receive refillable stainless steel or aluminum alloy beer kegs marked with an indicia of ownership from any person or entity other than the indicated owner. For purposes of this section, “indicia of ownership” means words, symbols, or registered trademarks printed, stamped, etched, attached, or otherwise displayed on the exterior surface of the beer keg that reasonably identifies the owner.

(b) If the seller is not the indicated owner, a junk dealer or recycler may purchase or receive refillable stainless steel or aluminum alloy beer kegs only if the seller or transferor provides a receipt from the indicated owner verifying the seller's current ownership or a document indicating that the seller or transferor is authorized by the indicated owner to sell or transfer the beer kegs. Copies of these documents shall be maintained by the junk dealer or recycler as part of the written record of the transaction.