Cal. Bus. & Prof. Code § 21609.1
(a) A junk dealer or recycler shall not possess any of the following material that was owned or previously owned by an agency, in the absence of a written certification on the letterhead of the agency owning or previously owning the material described in the certification that the agency has either sold the material described or is offering the material for sale, salvage, or recycling, and that the person possessing the certification and identified in the certification is authorized to negotiate the sale of that material:
(5) Reasonably recognizable street lights, traffic signals, and their reasonably recognizable related equipment, including, but not limited to, all of the following:
(c) For purposes of this section, the following definitions apply:
(2) “Appropriate law enforcement agency” means either of the following: