The following is pertinent text governing confidentiality:

Federal Court - LR 39.1(a)(6)

(6) Confidentiality.  Except as otherwise required by law or agreed by the litigants, or otherwise provided by this rule, all ADR proceedings under this rule, including communications, statements, disclosures and representations made by any party, attorney or other participant in the course of such proceeding, shall, in all respects, be confidential, and shall not be reported, recorded, placed in evidence, disclosed to anyone not a party to the litigation, made known to the trial court or jury, or construed for any purpose as an admission or declaration against interest. No party shall be bound by anything done or said during such proceedings unless a settlement or other agreement is reached.

State Court -  RCW 5.60.070 also restricts lawyers, party representatives and the mediator from disclosing matters occurring in the mediation:

(1) If there is a court order to mediate, a written agreement between the parties to mediate, or if mediation is mandated under RCW 7.70.100, then any communication made or materials submitted in, or in connection with, the mediation proceeding, whether made or submitted to or by the mediator, a mediation organization, a party, or any person present, are privileged and confidential and are not subject to disclosure in any judicial or administrative proceeding except:

(a) When all parties to the mediation agree, in writing, to disclosure;
(b) When the written materials or tangible evidence are otherwise subject to discovery, and were not prepared specifically for use in and actually used in the mediation proceeding;
(c) When a written agreement to mediate permits disclosure;
(d) When disclosure is mandated by statute;
(e) When the written materials consist of a written settlement agreement or other agreement signed by the parties resulting from the mediation proceeding;
(f) When those communications or written materials pertain solely to administrative matters incidental to the mediation proceeding, including the agreement to mediate; or
(g) In a subsequent action between the mediator and a party to the mediation arising out of the mediation.

(2) When there is a court order, a written agreement to mediate, or when mediation is mandated under RCW 7.70.100, as described in subsection (1) of this section, the mediator or a representative of a mediation organization shall not testify in any judicial or administrative proceeding unless:

(a) All parties to the mediation and the mediator agree in writing; or
(b) In an action described in subsection (1)(g)