Wash. Rev. Code § 26.27.201
(1) Except as otherwise provided in RCW 26.27.231, a court of this state has jurisdiction to make an initial child custody determination only if:
(b) A court of another state does not have jurisdiction under (a) of this subsection, or a court of the home state of the child has declined to exercise jurisdiction on the ground that this state is the more appropriate forum under RCW 26.27.261 or 26.27.271, and:
[ 2001 c 65 s 201.]