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.
With regard to whether recognition of a state judgment can be refused by the forum state on other than jurisdictional grounds, there are dicta to the effect that judgments for which extraterritorial operation is demanded under Article IV, § 1 and acts of Congress are
impeachable for manifest fraud. But unless the fraud affected the jurisdiction of the court, the vast weight of authority is against the proposition. Also, it is universally agreed that a judgment may not be impeached for alleged error or irregularity, 1 or as contrary to the public policy of the state where recognition is sought for it under the Full Faith and Credit Clause. 2 Previously listed cases indicate, however, that the Court in fact has permitted local policy to determine the merits of a judgment under the pretext of regulating jurisdiction. 3 Thus, in Cole v. Cunningham, 4 the Court sustained a Massachusetts court in enjoining, in connection with insolvency proceedings instituted in that state, a Massachusetts creditor from continuing in New York courts an action that had been commenced there before the insolvency suit was brought. This was done on the theory that a party within the jurisdiction of a court may be restrained from doing something in another jurisdiction opposed to principles of equity, it having been shown that the creditor was aware of the debtor's embarrassed condition when the New York action was instituted. The injunction unquestionably denied full faith and credit and commanded the assent of only five Justices.