The Supremacy Clause is a provision in the United States Constitution that establishes the Constitution, federal laws made pursuant to it, and treaties made under its authority as the "supreme Law of the Land". This means that they take priority over any conflicting state laws. The clause also provides that state courts are bound by, and state constitutions subordinate to, the supreme law. However, federal statutes and treaties must be within the parameters of the Constitution; that is, they must be pursuant to the federal governments enumerated powers, and not violate other constitutional limits on federal power, such as the Bill of Rights.

The Supremacy Clause is essentially a conflict-of-laws rule specifying that certain federal acts take priority over any state acts that conflict with federal law. Some jurists further argue that the clause also nullifies federal law that is in conflict with the Constitution, although this is disputed. The clause was added to the Constitution as a constitutional provision announcing the supremacy of federal law.

In summary, the Supremacy Clause is a provision in the United States Constitution that establishes the Constitution, federal laws made pursuant to it, and treaties made under its authority as the supreme law of the land, taking priority over any conflicting state laws.