Answer:
The Full Faith and Credit Clause.
Step-by-step explanation:
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 Constitution’s federalist structure allows each state to maintain its own government.
This structure creates a risk that multiple states will exercise their powers over the same issue or dispute, leading to confusion and uncertainty.
The Constitution’s Full Faith and Credit Clause mitigates that risk by adjusting the states’ interrelationships.
The Clause requires each state to give "Full Faith and Credit" to "the public Acts" of "every other State," such as other states’ statutes.
The Clause also requires states to give "Full Faith and Credit" to the "Records [] and judicial Proceedings of every other State."
The Supreme Court’s interpretation of the Clause has shifted over time.
The Court has settled on a doctrinal framework that treats out-of-state court judgments differently from out-of-state laws.
Whereas the modern Court generally requires states to give out-of-state judgments conclusive effect, states have more freedom to apply their own laws in their own courts, so long as they do not close their courts completely to claims based on other states’ laws.
The Clause also authorizes Congress to enact "general Laws" that "prescribe the Manner in which [states'] Acts, Records and Proceedings shall be proved, and the Effect thereof."
Congress has invoked this authority several times, such as to require federal and territorial courts to apply the same full faith and credit principles as state courts.
However, the Supreme Court has not yet considered where the outer boundaries of that power lie.