California Labor Code
No employer may do any of the following:
(a) Require, as a condition of employment, that an employee refrain from disclosing the amount of his or her wages.
(b) Require an employee to sign a waiver or other document that purports to deny the employee the right to disclose the amount of his or her wages.
(c) Discharge, formally discipline, or otherwise discriminate against an employee who discloses the amount of his or her wages.