Wash. Rev. Code § 4.84.185
In any civil action, the court having jurisdiction may, upon written findings by the judge that the action, counterclaim, cross-claim, third party claim, or defense was frivolous and advanced without reasonable cause, require the nonprevailing party to pay the prevailing party the reasonable expenses, including fees of attorneys, incurred in opposing such action, counterclaim, cross-claim, third party claim, or defense. This determination shall be made upon motion by the prevailing party after a voluntary or involuntary order of dismissal, order on summary judgment, final judgment after trial, or other final order terminating the action as to the prevailing party. The judge shall consider all evidence presented at the time of the motion to determine whether the position of the nonprevailing party was frivolous and advanced without reasonable cause. In no event may such motion be filed more than thirty days after entry of the order.
The provisions of this section apply unless otherwise specifically provided by statute.
RCW 4.84.185
Administrative law, frivolous petitions for judicial review: RCW 34.05.598.