California Code, Labor Code - LAB § 450

(a) No employer, or agent or officer thereof, or other person, may compel or coerce any employee, or applicant for employment, to patronize his or her employer, or any other person, in the purchase of any thing of value.

(b) For purposes of this section, to compel or coerce the purchase of any thing of value includes, but is not limited to, instances where an employer requires the payment of a fee or consideration of any type from an applicant for employment for any of the following purposes: