Washington Revised Code Title 2. Courts of Record § 2.44.030. Production of authority to act

The court, or a judge, may, on motion of either party, and on showing reasonable grounds therefor, require the attorney for the adverse party, or for any one of several adverse parties, to produce or prove the authority under which he or she appears, and until he or she does so, may stay all proceedings by him or her on behalf of the party for whom he or she assumes to appear.