Wash. Rev. Code § 11.96A.300
(1) Notice of mediation. A party may cause the matter to be subject to mediation by service of written notice of mediation on all parties or the parties' virtual representatives as follows:
(2) Procedure when notice of mediation served before a hearing is set. The following provisions apply when notice of mediation is served before a hearing on the matter is set:
(3) Procedure when notice of mediation served after hearing set. If the written notice of mediation required in subsection (1)(b) of this section is timely filed and served by a party and another party objects to mediation, by petition or orally at the hearing, the court shall order that mediation proceed except for good cause shown. Such order shall not be subject to appeal or revision. If the court determines that the matter should not be subject to mediation, the court shall dispose of the matter by:
(4) Selection of mediator; mediator qualifications.
(b) A qualified mediator must be:
(8) Costs of mediation. Costs of the mediation, including reasonable compensation for the mediator's services, shall be borne equally by the parties. The details of those costs and fees, including the compensation of the mediator, must be set forth in a mediation agreement between the mediator and all parties to the matter. Each party shall bear its own costs and expenses, including legal fees and witness expenses, in connection with the mediation proceeding:
[ 2001 c 14 s 4; 1999 c 42 s 505.]