Wash. Rev. Code § 81.28.250
The commission shall investigate all interstate, rates, fares, charges, classifications, or rules or practices in relation to the transportation of persons or property within this state, and if the commission determines that these rates, fares, charges, classification, or rules or practices are excessive or discriminatory, or are applied in violation of the act of congress entitled "An act to regulate commerce," approved February 4, 1887, as amended or supplemented, or in conflict with the rulings, orders, or regulations of the applicable federal regulatory agency, the commission shall apply, by petition, to the applicable federal regulatory agency for relief, and may present to the agency all facts concerning violations of the rulings, orders, or regulations of that agency, or violations of the act to regulate commerce as amended or supplemented.
RCW 81.28.250