<P> In Federalist No. 44, James Madison defends the Supremacy Clause as vital to the functioning of the nation . He noted that state legislatures were invested with all powers not specifically defined in the Constitution, but also said that having the federal government subservient to various state constitutions would be an inversion of the principles of government, concluding that if supremacy were not established "it would have seen the authority of the whole society everywhere subordinate to the authority of the parts; it would have seen a monster, in which the head was under the direction of the members". </P> <P> The constitutional principle derived from the Supremacy Clause is federal preemption . Preemption applies regardless of whether the conflicting laws come from legislatures, courts, administrative agencies, or constitutions . For example, the Voting Rights Act of 1965, an act of Congress, preempts state constitutions, and Food and Drug Administration regulations may preempt state court judgments in cases involving prescription drugs . </P> <P> Congress has preempted state regulation in many areas . In some cases, such as the 1976 Medical Device Regulation Act, Congress preempted all state regulation . In others, such as labels on prescription drugs, Congress allowed federal regulatory agencies to set national minimum standards, but did not preempt state regulations imposing more stringent standards than those imposed by federal regulators . Where rules or regulations do not clearly state whether or not preemption should apply, the Supreme Court tries to follow lawmakers' intent, and prefers interpretations that avoid preempting state laws . </P> <P> In Ware v. Hylton, 3 U.S. (3 Dall .) 199 (1796), the United States Supreme Court for the first time applied the Supremacy Clause to strike down a state statute . Virginia had passed a statute during the Revolutionary War allowing the state to confiscate debt payments by Virginia citizens to British creditors . The Supreme Court found that this Virginia statute was inconsistent with the Treaty of Paris with Britain, which protected the rights of British creditors . Relying on the Supremacy Clause, the Supreme Court held that the treaty superseded Virginia's statute, and that it was the duty of the courts to declare Virginia's statute "null and void". </P>

Who ensures that the states abide by constitutional and federal law