Wash. Rev. Code § 4.24.520
In order to protect the free flow of information from citizens to their government, an agency receiving a complaint or information under RCW 4.24.510 may intervene in and defend against any suit precipitated by the communication to the agency. In the event that a local governmental agency does not intervene in and defend against a suit arising from any communication protected under chapter 234, Laws of 1989, the office of the attorney general may intervene in and defend against the suit. An agency prevailing upon the defense provided for in RCW 4.24.510 shall be entitled to recover costs and reasonable attorneys' fees incurred in establishing the defense. If the agency fails to establish the defense provided for in RCW 4.24.510, the party bringing the action shall be entitled to recover from the agency costs and reasonable attorney's fees incurred in proving the defense inapplicable or invalid.
RCW 4.24.520