In a case decided in 1887, however, the Court remarked: ''Without doubt the constitutional requirement, Art. IV, Sec. 1, that 'full faith and credit shall be given in each State to the public acts, records, and judicial proceedings of every other State,' implies that the public acts of every State shall be given the same effect by the courts of another State that they have by law and usage at home.''And this proposition was later held to extend to state constitutional provisions.
More recently this doctrine has been stated in a very mitigated form, the Court saying that where statute or policy of the forum State is set up as a defense to a suit brought under the statute of another State or territory, or where a foreign statute is set up as a defense to a suit or proceedings under a local statute, the conflict is to be resolved, not by giving automatic effect to the full faith and credit clause and thus compelling courts of each State to subordinate its own statutes to those of others but by appraising the governmental interest of each jurisdiction and deciding accordingly.
That is, the full faith and credit clause, in its design to transform the States from independent sovereigns into a single unified Nation, directs that a State, when acting as the forum for litigation having multistate aspects or implications, respect the legitimate interests of other States and avoid infringement upon their sovereignty, but because the forum State is also a sovereign in its own right, in appropriate cases it may attach paramount importance to its own legitimate interests.