In the United States Supreme Court case of The United States v. Nathaniel Cox, the court was tasked with determining whether a federal statute that prohibited citizens from transporting slaves across state lines was constitutional. At issue in this case was whether Congress had exceeded its authority under Article I, Section 9 of the Constitution by enacting such legislation. In an opinion delivered by Chief Justice Taney, it was held that Congress did not have the power to pass such a law and thus declared it unconstitutional. Furthermore, Chief Justice Taney argued that if Congress were allowed to regulate slavery within states then they would be able to interfere with matters which are reserved for individual states according to their own laws and constitutions - something which is expressly forbidden by Article IV of the Constitution. Ultimately, this decision established limits on Congressional powers when it comes to regulating slavery within individual states and set precedent for future cases involving similar issues regarding federalism and state sovereignty rights.

In the case of The United States v. Nathaniel Cox, the Supreme Court was asked to decide whether a state court had jurisdiction over an indictment for a crime committed on board of a vessel belonging to the United States Navy. Chief Justice Taney wrote in dissent that he believed that it did not have such jurisdiction because Congress had exclusive authority over all matters relating to naval vessels and their crews under Article I, Section 8 of the Constitution. He argued that this power extended even beyond American territorial waters and thus any criminal proceedings against members of its crew must be conducted by federal courts or tribunals established by Congress itself. Furthermore, he noted that allowing states to exercise jurisdiction would lead to confusion as different states could potentially have conflicting laws governing similar offenses which would create problems with enforcement and compliance with international law obligations.