Cal. Penal Code § 22820

Nothing in this division prohibits any person who is a peace officer, as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2, from purchasing, possessing, transporting, or using any tear gas or tear gas weapon if the person has satisfactorily completed a course of instruction approved by the Commission on Peace Officer Standards and Training in the use of tear gas.