Wash. Rev. Code § 66.98.020
If any clause, part, or section of this act shall be adjudged invalid, such judgment shall not affect nor invalidate the remainder of the act, but shall be confined in its operation to the clause, part, or section directly involved in the controversy in which such judgment was rendered. If the operation of any clause, part, or section of this act shall be held to impair the obligation of contract, or to deny to any person any right or protection secured to him or her by the Constitution of the United States of America, or by the Constitution of the state of Washington, it is hereby declared that, had the invalidity of such clause, part[,] or section been considered at the time of the enactment of this act, the remainder of the act would nevertheless have been adopted without such and any and all such invalid clauses, parts, or sections.
RCW 66.98.020