Supremacy Clause — Federal Law as the Supreme Law of the Land
The Supremacy Clause (Article VI, Clause 2) provides: "This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding." This clause establishes the foundational principle of federal supremacy — when valid federal law conflicts with state law, federal law wins. Without this principle, the United States would be a loose confederation of sovereign states, each free to disregard federal legislation. The Supremacy Clause makes the Constitution, federal statutes, and treaties superior to all state constitutions, statutes, regulations, and common law. It is the textual foundation for the federal preemption doctrine — the principle that federal law "preempts" (overrides) state law when the two conflict, when Congress intends to occupy an entire field of regulation, or when state law would frustrate federal purposes. The Supremacy Clause also binds state judges — they must apply federal law even when it conflicts with state law, and they must follow the Supreme Court's interpretation of the Constitution. The clause does not, however, give the federal government unlimited power — it makes federal law supreme only when that law is made "in Pursuance" of the Constitution. An unconstitutional federal law has no supremacy over state law. See Federal Preemption for the detailed preemption framework, Commerce Clause for the primary source of federal regulatory authority, and Tenth Amendment for the states' reserved powers.
Current Law (2026)
| Parameter | Value |
|---|---|
| Constitutional provision | Article VI, cl. 2 |
| Hierarchy | Constitution > federal statutes > treaties > state constitutions > state statutes > state regulations |
| Federal preemption | State law is preempted when it conflicts with federal law, or when Congress intends to occupy the field |
| State judges | Must apply federal law and follow Supreme Court interpretations |
| Limitation | Federal law must be "made in Pursuance" of the Constitution — unconstitutional federal law has no supremacy |
| Key cases | McCulloch v. Maryland (1819), Gibbons v. Ogden (1824), Arizona v. United States (2012), Altria Group v. Good (2008) |
Legal Authority
- U.S. Constitution, Art. VI, cl. 2 — "This Constitution, and the Laws of the United States which shall be made in Pursuance thereof . . . shall be the supreme Law of the Land"
- McCulloch v. Maryland (1819) — States cannot tax or impede valid federal instrumentalities; federal law is supreme
- Gibbons v. Ogden (1824) — Federal commerce regulation preempts conflicting state regulation
- Arizona v. United States (2012) — Federal immigration law preempts most state immigration enforcement measures
How It Works
The Supremacy Clause creates a clear legal hierarchy: the Constitution is supreme over all law; federal statutes enacted pursuant to the Constitution are supreme over state law; treaties ratified by the Senate rank on par with federal statutes (with later-in-time rules resolving conflicts between them); and state constitutions, statutes, and regulations all rank below valid federal law. A state constitutional amendment cannot override a federal statute, and a state statute cannot contradict a federal regulation. The practical application is the preemption doctrine: when federal and state law conflict, state law must yield. Preemption takes three forms — express preemption (Congress explicitly states federal law overrides state law), conflict preemption (it is impossible to comply with both laws, or state law would frustrate federal purposes), and field preemption (Congress has so thoroughly occupied a regulatory field that no room remains for state regulation). The Supreme Court recognizes a presumption against preemption in areas of traditional state regulation, requiring Congress to make its intent clear. See the Federal Preemption page for detailed framework analysis.
State judges are specifically bound by the Supremacy Clause — they "shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding" — and cannot refuse to enforce federal statutes or ignore Supreme Court precedent interpreting the Constitution. If a state court applies state law in a way that conflicts with federal law, the losing party can seek Supreme Court review. Critically, the Supremacy Clause gives supremacy only to federal laws made "in Pursuance" of the Constitution. A federal statute that exceeds Congress's enumerated powers or violates individual rights has no supremacy over state law — which is why judicial review exists. Courts determine whether a federal law is constitutionally valid; if not, it has no preemptive effect. States may and do challenge federal laws as unconstitutional precisely to avoid preemption when they believe Congress has overstepped its authority.
How It Affects You
If you're a business operating at the intersection of federal and state law: The Supremacy Clause is most practically significant where federal law prohibits what your state permits (or vice versa) — and 2026's most vivid examples are cannabis, firearms, and immigration enforcement.
Cannabis: Federal law (Controlled Substances Act, 21 U.S.C. § 812) still classifies marijuana as a Schedule I controlled substance, regardless of state legalization. State legalization statutes don't preempt federal law — they only constrain state enforcement. A state-legal cannabis business still faces: banks refusing accounts (federal banks fear BSA/AML violations), inability to deduct ordinary business expenses under IRS § 280E (which bars deductions for trafficking Schedule I substances), and theoretical federal criminal exposure. The DEA rescheduling process (moving marijuana to Schedule III) would reduce but not eliminate the Supremacy Clause tension.
Firearms: "Second Amendment Sanctuary" laws enacted by many states and counties purport to nullify federal firearms regulations — the National Firearms Act, the Gun Control Act, ATF registration requirements. Under the Supremacy Clause, these laws have no legal effect. Federal firearm regulations remain valid and binding on residents of those states. State sanctuary laws constrain state officers from assisting federal enforcement (a valid exercise of the anti-commandeering doctrine) — but they don't shield individuals from federal ATF prosecution.
Employment and consumer protection: Federal law typically sets a floor that states can exceed unless Congress has preempted the field. A state minimum wage above the federal minimum is valid — the FLSA doesn't preempt more generous state wages. A state consumer protection law that exceeds federal requirements may be valid or preempted depending on whether Congress intended to occupy the field. Always run the preemption analysis before assuming state law fills gaps in federal regulation.
If you're a state official (AG, legislator, governor) testing the boundaries of federal preemption: The Supremacy Clause has an important counterpart: the anti-commandeering doctrine (Murphy v. NCAA, 2018; Printz v. United States, 1997). Congress cannot force state legislatures to enact laws or state officers to enforce federal law. This creates the following landscape:
- Your state can decline to enforce federal law (immigration sanctuary policies, cannabis non-enforcement). State officers don't have to do federal law enforcement's job.
- Your state cannot enact laws that contradict valid federal law. A state law requiring local police to arrest undocumented immigrants for being undocumented — an exclusively federal status offense — is preempted. A state law saying local police won't cooperate with ICE detainer requests is valid.
- To test whether your proposed state law is preempted, run through the three categories: (1) Express preemption — does the federal statute include an explicit preemption clause? (2) Conflict preemption — is it physically impossible to comply with both? Or does your state law obstruct federal purposes? (3) Field preemption — has Congress so thoroughly occupied this regulatory area that no room remains for state action? (Arizona v. United States found immigration largely field-preempted.)
- The presumption against preemption helps you: in areas of traditional state authority (health, safety, family law, land use), courts presume that federal law doesn't preempt state law unless Congress has made its intent clear. Ambiguous federal statutes don't preempt by accident.
If you're a litigant or attorney arguing a preemption defense: Lead with express preemption — look for the preemption clause in the federal statute, and read it carefully. Cipollone v. Liggett Group (1992) established that express preemption clauses are construed narrowly. If there's no express clause, argue conflict preemption — either physical impossibility of complying with both laws, or frustration of federal purpose. Wyeth v. Levine (2009) is the definitive statement that conflict preemption requires something more than the mere existence of federal regulation: the defendant must show that state law directly conflicts with federal requirements or makes it impossible to comply with federal standards.
File your preemption argument as a motion to dismiss or motion for summary judgment early — a successful preemption ruling ends the state law claim entirely, which is more efficient than litigating through trial. Federal courts have jurisdiction over preemption claims because they arise under federal law (28 U.S.C. § 1331) even when the underlying case was filed in state court — removal is available.
If you're a state court judge: Article VI, Clause 2 requires you to apply federal law — including the Constitution as interpreted by the Supreme Court — even when it conflicts with your state's constitution or statutes. Cooper v. Aaron (1958) settled definitively that state officials cannot nullify Supreme Court decisions. If parties raise preemption, you are the first court to decide it — federal courts will review your preemption ruling, but de novo (fresh) review by a federal court of appeals means your analysis must be legally sound. If you believe a federal statute's constitutionality is at issue, note the question clearly for the record.
State Variations
The Supremacy Clause applies uniformly to all states — that is its purpose:
- States cannot "nullify" federal law (this was settled by the Civil War and Cooper v. Aaron, 1958)
- States vary in how aggressively they test the boundaries of federal preemption — some states actively legislate in areas of federal-state tension (marijuana, immigration, gun regulation)
- State courts vary in how receptive they are to preemption arguments — some apply the presumption against preemption more strongly than others
- State constitutional provisions cannot override federal law, but they can provide greater protections for individual rights than the federal Constitution
Implementing Regulations
This is a constitutional provision with no implementing regulations in the Code of Federal Regulations. Key judicial doctrine includes:
- McCulloch v. Maryland (1819) — Chief Justice Marshall's landmark opinion establishing federal supremacy in concrete terms. Maryland attempted to tax the Second Bank of the United States; Marshall held the tax unconstitutional because states cannot impede valid federal instrumentalities. McCulloch is the foundational statement that the Supremacy Clause makes federal law and institutions immune from state interference.
- Gibbons v. Ogden (1824) — Held that federal commerce power and the Supremacy Clause preempted New York's grant of a steamboat monopoly on waters also regulated by federal law. One of the earliest and most important preemption decisions, establishing that state regulation must yield when it conflicts with valid federal commerce regulation.
- Crosby v. National Foreign Trade Council (2000) — Struck down a Massachusetts law restricting state contracts with companies doing business in Burma (Myanmar), finding it conflict-preempted by a federal statute imposing sanctions on Burma. Key precedent on conflict preemption — even when Congress has not expressly preempted state law, state action that frustrates federal foreign policy objectives is invalid under the Supremacy Clause.
- Arizona v. United States (2012) — Struck down most of Arizona's S.B. 1070 immigration enforcement law as preempted by federal immigration statutes. The Court held that immigration is a field Congress has so thoroughly occupied that state enforcement measures — even those designed to assist federal enforcement — are largely preempted. Defines the modern scope of field preemption in immigration.
- Murphy v. NCAA (2018) — Struck down the Professional and Amateur Sports Protection Act (PASPA), which prohibited states from authorizing sports gambling, as violating the anti-commandeering doctrine. While not a straightforward Supremacy Clause case, Murphy clarifies the critical distinction between federal supremacy (valid — federal law overrides conflicting state law) and federal commandeering (invalid — Congress cannot order states to prohibit something under state law). This distinction shapes how federal-state conflicts in marijuana, firearms, and immigration are analyzed.
Pending Legislation
No standalone legislation pending in the 119th Congress directed at the Supremacy Clause itself. Preemption disputes arise in virtually every area of federal-state regulatory overlap — see Federal Preemption Doctrine and Tenth Amendment — Federalism for legislative activity in areas where Supremacy Clause questions most frequently arise.
Recent Developments
The Supremacy Clause and preemption remain at the center of federal-state conflicts over marijuana legalization (state-legal but federally prohibited), immigration enforcement (federal preemption of state enforcement measures after Arizona v. United States), gun regulation (state "Second Amendment sanctuary" laws claiming to nullify federal firearms regulations), and environmental regulation (federal preemption of state climate policies). The interaction between the Supremacy Clause and the anti-commandeering doctrine creates a nuanced framework: federal law is supreme (states cannot contradict it), but the federal government cannot force states to enforce it (anti-commandeering). This distinction is critical in immigration, marijuana, and firearms policy.