In Holder v. Holder, 305 F.3d 854 (9th Cir., 2002), the father petitioned for return of his children from Washington State to Germany. The District Court stayed the action pending resolution of the father's state court appeal in his California divorce action. The father appealed and mother cross- appealed the denial of her request for attorney's fees and costs. Federal courts give preclusive effect to state court judgments to the extent required by statute and by the res judicata principles embodied in federal common law. In situations in which federal courts apply the generic full faith and credit statute, they generally give state court judgments the same res judicata or issue preclusive effect that they would be given by another court of that state. The fact that the father filed for custody in state court and failed to raise his Hague Convention claim in state court did not mean that a final judgment from that state court would bar him, on res judicata principles, from raising his Hague Convention claim in federal court.

Under the Hague Convention and ICARA, parent may choose to bring his Hague Convention claim in either federal or state court, and he may pursue his remedies under both the Convention and state law. International Child Abduction Convention, Art. 1 et seq., 1988 WL 411501. Federal courts adjudicating petitions under the Hague Convention must accord preclusive effect only to those state court judgments ordering or denying the return of a child pursuant to the Hague Convention in an action under ICARA. Federal court, in an action for the return of a child under the Hague Convention, does not give preclusive effect to a state court adjudication of issues in a situation in which that court did not have a Hague petition before it and did not order the return of the children pursuant to the Convention.

The district court abused its discretion in staying under Colorado River the father's action under the Hague Convention, pending conclusion of state court custody proceedings, since there was substantial doubt that a final determination in the custody proceeding would resolve all of the issues in the federal Hague Convention petition, because the father did not bring a Hague Convention claim in his state proceeding and issues relevant to the adjudication of a Hague Convention petition are distinct from those relevant to a custody determination under state law, and since the mother and the children were currently located in a third jurisdiction and federal law and a federal treaty provided the rule of decision. Under the Colorado River Doctrine, considerations of wise judicial administration, giving regard to conservation of judicial resources and comprehensive disposition of litigation, may justify a decision by the district court to stay federal proceedings pending the resolution of concurrent state court proceedings involving the same matter, and exact parallelism is not required, and it is enough if the two proceedings are substantially similar. Generally, as between state and federal courts with concurrent jurisdiction, the rule is that the pendency of an action in the state court is no bar to proceedings concerning the same matter in the federal court having jurisdiction, and the Colorado River doctrine is a narrow exception to the virtually unflagging obligation of the federal courts to exercise the jurisdiction given them. Although it is dispositive, in determining that a stay under Colorado River is inappropriate, that the state court judgment will not resolve all of the issues before the federal court, the following factors, though not exclusive, are also relevant: (1) whether the state court first assumed jurisdiction over the property; (2) inconvenience of the federal forum; (3) the desirability of avoiding piecemeal litigation; (4) the order in which jurisdiction was obtained by the concurrent forums; (5) whether federal law or state law provides the rule of decision on the merits; (6) whether the state court proceedings are inadequate to protect the federal litigant's rights; and (7) whether exercising jurisdiction would promote forum shopping.

The factors relevant to a Colorado River stay in a given case are subjected to a flexible balancing test, in which one factor may be accorded substantially more weight than another depending on the circumstances of the case, and with the balance heavily weighted in favor of the exercise of jurisdiction. Because of the pendency of a state court custody action, the Colorado River factors motivated by order and efficiency concerns should be subordinated to those motivating ICARA and the Hague Convention, particularly the requirement that courts expeditiously resolve claims. For purposes of the doctrine of judicial estoppel, the father's position that California had jurisdiction over his custody claim was not necessarily inconsistent with his position that Washington, not California, had jurisdiction over his claim under ICARA and the Hague convention. Filing for custody in California was insufficient to find an uncoerced intent to relinquish Hague Convention rights on this basis alone, so as to find a waiver of those rights, as many of the reasons that the father may have had for filing for custody in California were wholly consistent with a desire to have them finally adjudicated in Germany.