Article VI’s Supremacy Clause identifies the Constitution, federal laws made in pursuance of it, and treaties made under United States authority as the supreme law of the land. State judges are bound by that law despite contrary state constitutions or statutes. The clause supplies a rule for resolving legal conflicts. It does not mean any statement by any federal official automatically overrides state law. [1]
Rules that determine the answer
The practical doctrine is preemption. Federal law can expressly displace state requirements through statutory language, or do so by implication. Implied preemption includes occupation of a regulatory field and conflicts in which simultaneous compliance is impossible or state law obstructs federal objectives. The inquiry focuses on the particular federal law’s text, structure, purpose, and scope. A broad statement that a topic is “federal” is not a substitute for that analysis. [2]
The Constitution remains a limit on federal action: supremacy is not an independent grant of unlimited regulatory power. A federal statute or agency rule must rest on valid authority, and preemption does not automatically decide every issue about federal direction of state governments. [1] Nor does finding one state requirement preempted necessarily invalidate every related state law or create a damages remedy. Those are separate questions requiring the relevant statute and procedural law.
What to do next
- Identify the actual federal and state provisions and the conduct each regulates. Make sure they apply to the same person and activity.
- Look for an express preemption provision and any savings clause preserving state authority or remedies.
- If no express answer resolves the issue, examine whether federal law occupies the field or produces a genuine conflict.
- Check controlling decisions interpreting that law. Distinguish a rule’s validity, its preemptive scope, and the available procedure for challenging it.
Practical example
Suppose a federal statute establishes a minimum protection and expressly allows states to provide more. A stronger state requirement is not invalid merely because it differs from the federal minimum. Conversely, a state cannot preserve a conflicting rule simply by declaring it important when valid federal law displaces that requirement. The wording of the particular statute determines which situation exists.
For related situations, see Perpich and National Guard federalization and ERISA coverage and benefit claims.
Primary sources
- Constitution Annotated: overview of the Supremacy Clause
- Congressional Research Service: Federal Preemption, a Legal Primer
Sources checked: October 31, 2026.