Wash. Rev. Code § 7.70.160
In any action under this section [chapter], an attorney that has drafted, or assisted in drafting and filing an action, counterclaim, cross-claim, third-party claim, or a defense to a claim, upon signature and filing, certifies that to the best of the party's or attorney's knowledge, information, and belief, formed after reasonable inquiry it is not frivolous, and is well-grounded in fact and is warranted by existing law or a good faith argument for the extension, modification, or reversal of existing law, and that it is not interposed for any improper purpose, such as to harass or to cause frivolous litigation. If an action is signed and filed in violation of this rule, the court, upon motion or upon its own initiative, may impose upon the person who signed it, a represented party, or both, an appropriate sanction, which may include an order to pay to the other party or parties the amount of the reasonable expenses incurred because of the filing of the action, counterclaim, cross-claim, third-party claim, or a defense to a claim, including a reasonable attorney fee. The procedures governing the enforcement of RCW 4.84.185 shall apply to this section.
RCW 7.70.160
Findings-Intent-Part headings and subheadings not law-Severability-2006 c 8: See notes following RCW 5.64.010.