RCW 50A.40.010: Employers.

(1) It is unlawful for any employer to:

(a) Interfere with, restrain, or deny the exercise of, or the attempt to exercise, any valid right provided under this title; or

(b) Discharge or in any other manner discriminate against any employee for opposing any practice made unlawful by this title.

(2) It is unlawful for any person to discharge or in any other manner discriminate against any employee because the employee has:

(a) Filed any complaint, or has instituted or caused to be instituted any proceeding, under or related to this title;

(b) Given, or is about to give, any information in connection with any inquiry or proceeding relating to any right provided under this title; or

(c) Testified, or is about to testify, in any inquiry or proceeding relating to any right provided under this title.

(3) As provided in RCW 50A.40.020 and 50A.40.030, the department will investigate allegations of unlawful acts and determine damages, as necessary.