(1) The superior court shall assess costs and reasonable attorneys' fees against a party who appeals the award and fails to improve his or her position on the trial de novo. The court may assess costs and reasonable attorneys' fees against a party who voluntarily withdraws a request for a trial de novo if the withdrawal is not requested in conjunction with the acceptance of an offer of compromise.

(2) For the purposes of this section, "costs and reasonable attorneys' fees" means those provided for by statute or court rule, or both, as well as all expenses related to expert witness testimony, that the court finds were reasonably necessary after the request for trial de novo has been filed.

(3) If the prevailing party in the arbitration also prevails at the trial de novo, even though at the trial de novo the appealing party may have improved his or her position from the arbitration, this section does not preclude the prevailing party from recovering those costs and disbursements otherwise allowed under chapter 4.84 RCW, for both actions.