Supremacy Clause

The Supremacy Clause of the Constitution of the United States (Article VI, Clause 2) establishes that the U.S. constitution, federal laws, and treaties override any state laws that conflict with them. It promulgates that all state laws, state courts, and state constitutions are subordinate to the U.S. Constitution and federal laws and treaties made by the U.S. government.

However, federal statutes must be pursuant to the U.S. Constitution for the Supremacy Clause to apply; that does not violate the U.S. Constitution, such as the Bill of Rights. It is the prerogative of the federal judiciary of the United States to preempt state statutes through judicial review.

The Supremacy Clause is essentially a conflict-of-laws rule mandating the priority of federal regulation over state regulation to prevent states from impeding the enforcement of federal law.

The Supremacy Clause follows Article XIII of the Articles of Confederation, the predecessor of the Constitution, which provided that "Every State shall abide by the determination of the [Congress], on all questions which by this confederation are submitted to them." As a constitutional provision identifying the supremacy of federal law, the Supremacy Clause assumes the underlying priority of federal authority, albeit only when that authority is expressed in the Constitution itself; no matter what the federal or state governments might wish to do, they must stay within the boundaries of the Constitution. Consequently, the Supremacy Clause is considered a cornerstone of the United States' federal political structure.