Article IV, Section 1:
Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof.
The Supreme Court reinterpreted the Full Faith and Credit Clause in Chicago & Alton Railroad v. Wiggins Ferry Co., in which the Court indicated that the Clause itself, not just the statute Congress passed to implement the Clause, compelled its holding in Mills requiring states to give out-of-state judgments conclusive effect.1 Cases following Chicago & Alton Railroad similarly characterized the Clause itself as imposing this requirement, often without mentioning the full faith and credit statute.2 The Court did not explain why it reconceptualized Mills's holding as a constitutional command rather than a legislative mandate.3
Thus, under the Court’s current interpretation of the Clause, courts ordinarily must give an out-of-state judgment the same effect it would have in the state that issued it.4 A court may not disregard an out-of-state judgment merely because it disagrees with the reasoning underlying the judgment or deems it to be wrong on the merits
; the Clause precludes any inquiry into the merits of the cause of action, the logic or consistency of the decision, or the validity of the legal principles on which the judgment is based.
5 Nor may state courts decline to enforce other states’ judgments for public policy reasons.6
Still, the modern Court recognizes limited circumstances in which a state may refuse to enforce an out-of-state judgment.7 For example, a state need not honor a judgment if the rendering court lacked jurisdiction to enter it.8 A court’s power to scrutinize another court’s jurisdiction is limited, however.9 The court must ordinarily presume that the issuing court had jurisdiction unless the judicial record or other evidence reveals a jurisdictional defect.10 If the parties in the first action litigated whether the rendering court had jurisdiction, and the first court answered that question affirmatively, the second court must accept that conclusion.11
Because the Full Faith and Credit Clause ordinarily requires states to give out-of-state judgments the same effect as the states that issued them,12 whether a judgment has conclusive effect depends on whether the issuing court would regard the judgment as final.
While some states hold that a judgment is final for full faith and credit purposes even when it is pending on appeal, other states hold that a judgment is not final until the appellate process has concluded.13