Final answer:
The "Full Faith and Credit" Clause in Article IV, Section 1 of the US Constitution requires states to respect and adhere to the legal decisions rendered in other states.
Step-by-step explanation:
The provision of the US Constitution that requires a decision rendered in one state to be respected and abided by in all other states is found in Article IV, Section 1. This is known as the "Full Faith and Credit" Clause. It mandates that states must recognize the public acts, records, and judicial proceedings of every other state. This clause plays a critical role in ensuring interstate cooperation and legal consistency across the United States. For example, a marriage license or court judgment issued in one state must be honored in all others. Furthermore, the Clause has been at the center of debates such as the legality of same-sex marriage prior to the Supreme Court's ruling in Obergefell v. Hodges, which legalized same-sex marriage nationwide.
It is important to note that while this clause ensures cross-state recognition of legal matters, the Supremacy Clause in Article VI asserts federal laws and treaties as the supreme law of the land, which sometimes can lead to conflicts when federal law and state laws differ.