If the employee's engagement in protected activities was a substantial factor in bringing about the employer's decision, RCW 49.17.160 has been violated. "Substantial factor" means a significant motivating factor in bringing about the employer's decision. "Substantial factor" does not mean the only factor or the main factor in the challenged act or decision. Ultimately, the issue as to whether an employee's engagement in protected activities was a substantial factor for the discharge or other adverse action is determined on the basis of the facts in the particular case.