Wash. Rev. Code § 70A.15.3170
As an additional means of enforcing this chapter, the governing body or board may accept an assurance of discontinuance of any act or practice deemed in violation of this chapter or of any ordinance, resolution, rule or regulation adopted pursuant hereto, from any person engaging in, or who has engaged in, such act or practice. Any such assurance shall specify a time limit during which such discontinuance is to be accomplished. Failure to perform the terms of any such assurance shall constitute prima facie proof of a violation of this chapter or the ordinances, resolutions, rules or regulations, or order issued pursuant thereto, which make the alleged act or practice unlawful for the purpose of securing any injunction or other relief from the superior court as provided in RCW 70A.15.3140.
RCW 70A.15.3170