Wash. Rev. Code § 50A.50.090
After having acquired jurisdiction for review, the commissioner shall review the proceedings in question. Prior to rendering a decision, the commissioner may order the taking of additional evidence by an administrative law judge to be made a part of the record in the case. Upon the basis of evidence submitted to the administrative law judge and such additional evidence as the commissioner may order to be taken, the commissioner shall render a decision in writing affirming, modifying, or setting aside the decision of the administrative law judge. Alternatively, the commissioner may order further proceedings to be held before the administrative law judge, upon completion of which the administrative law judge shall issue a new decision in writing affirming, modifying, or setting aside the previous decision of the administrative law judge. The new decision of the administrative law judge may be appealed as provided under RCW 50A.50.080. The commissioner shall mail the decision of the commissioner to the interested parties at their last known addresses.
RCW 50A.50.090