California Code, Labor Code - LAB § 1557

An employer shall not discharge, threaten to discharge, demote, suspend, or in any manner discriminate or retaliate against an employee for exercising or attempting to exercise their rights under this part, filing a complaint with the Labor Commissioner alleging a violation of this part, cooperating in an investigation or prosecution of an alleged violation of this part, or for any action taken by an employee to invoke, or assist in any manner in, the enforcement of this part.