Wash. Rev. Code § 2.08.150
Whenever a like request shall be addressed by the judge, or by a majority of the judges (if there be more than one) of the superior court of any county to the superior judge of any other county, he or she is hereby empowered, if he or she deem it consistent with the state of judicial business in the county or counties whereof he or she is a superior judge (and in such case it shall be his or her duty to comply with such request), to hold a session of the superior court of the county the judge or judges whereof shall have made such request, at the seat of judicial business of such county, in such quarters as shall be provided for such session by the board of county commissioners, and during such period as shall have been specified in the request, or such shorter period as he or she may deem necessary by the state of judicial business in the county or counties whereof he or she is a superior judge.
RCW 2.08.150