California Code, Public Utilities Code - PUC § 98161

(a) All individuals shall have equal opportunity to obtain and hold employment, and to advance in that employment, without discrimination on any basis listed in subdivision (a) of Section 12940 of the Government Code, as those bases are defined in Sections 12926 and 12926.1 of the Government Code, except as otherwise provided in Section 12940 of the Government Code.

(b) An employee shall not be subject to punitive action, denied promotion, or threatened with that treatment for the exercise of lawful action as an elected, appointed, or recognized representative of an employee bargaining unit.