Wash. Rev. Code § 35.44.250
At the time fixed for hearing in the notice thereof or at such further time as may be fixed by the court, the superior court shall hear and determine the appeal without a jury and the cause shall have preference over all other civil causes except proceedings relating to eminent domain in cities and towns and actions of forcible entry and detainer. The judgment of the court shall confirm, unless the court shall find from the evidence that such assessment is founded upon a fundamentally wrong basis and/or the decision of the council or other legislative body thereon was arbitrary or capricious; in which event the judgment of the court shall correct, change, modify, or annul the assessment insofar as it affects the property of the appellant.
RCW 35.44.250