The doctrine of comity allows a domestic court to recognize and enforce the judgment of a foreign court even though it is under no legal obligation to do so. Comity is generally understood to be a voluntary courtesy, but in Washington it now appears to be something more like a rule of law.
In In The Matter of the Estate of Toland, the Washington Supreme Court found a trial court abused its discretion by not recognizing a Japanese divorce decree as a matter of comity. In particular, the six Justice majority opinion found that the trial court erred by basing its decision to deny comity on the lack of notice provided in a subsequent guardianship proceedings. The Supreme Court then essentially ordered the trial court to extend comity to the Japanese court by remanding with instructions to register the divorce decree. In this decision, the Washington Supreme Court gave notice to trial courts that they should extend comity as a firm rule of law unless they have a good reason not to.
Justice Wiggins wrote a three Justice dissent that agreed with the majority only insofar as the evidence before the trial court did not support denying comity at summary judgment – but the dissenters would have remanded for a full trial to allow the trial court to decide whether to extend or deny comity on a full record.