What is the Tenth Amendment?

The Tenth Amendment reads in full: 'The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.' Ratified December 15, 1791, it was the last of the ten amendments that make up the Bill of Rights. The Amendment was included to answer Anti-Federalist concerns that the new Constitution's broad grants of power to the federal government -- particularly the Necessary and Proper Clause of Article I, Section 8 -- would swallow the states and eliminate meaningful self-governance at the local level. James Madison, drafting the Bill of Rights, included the Tenth Amendment as a structural statement of the principle underlying the Constitution's design: the federal government is a government of enumerated and therefore limited powers, and everything not enumerated is left where it was before the Constitution -- with the states or with the people. The Amendment did not invent this principle; it restated one already embedded in the structure of Article I. But by putting the reservation of powers expressly into the Constitution's text, it gave Anti-Federalists the textual anchor they had demanded and provided later courts with a constitutional basis for limiting federal encroachments on state authority.

The Supreme Court's early Tenth Amendment jurisprudence was largely deferential to federal power. In McCulloch v. Maryland, 17 U.S. (4 Wheat.) 316 (1819), Chief Justice John Marshall held that Congress had implied constitutional authority to charter the Second Bank of the United States even though the Constitution does not expressly grant such a power, reasoning that the Necessary and Proper Clause gave Congress the means to execute all of the powers the Constitution does enumerate. Marshall also held that Maryland could not tax the Bank, because the power to tax involves the power to destroy and a state may not use that power against an instrument of the federal government. Critically, Marshall rejected the argument that the word 'expressly' from the Articles of Confederation's analogous provision had been carried over into the Tenth Amendment: the Constitution's Framers had deliberately omitted 'expressly' from the Tenth Amendment, leaving room for implied federal powers. For most of the nineteenth and early twentieth centuries, the Tenth Amendment functioned primarily as a truism -- a reminder that the federal government could not act without constitutional authority -- rather than as an independent source of judicially enforceable limits on Congress.

The modern Tenth Amendment's teeth grew from two distinct lines of cases. The first line involves the anti-commandeering doctrine. In New York v. United States, 505 U.S. 144 (1992), the Court held 6-3 in an opinion by Justice O'Connor that a federal statute requiring states to 'take title' to radioactive waste they could not dispose of by a certain date was unconstitutional: Congress may not compel a state legislature to enact or enforce a federal regulatory program. The anti-commandeering rule was extended to executive branch state officers in Printz v. United States, 521 U.S. 898 (1997), where the Court struck down 5-4 in an opinion by Justice Scalia the interim provision of the Brady Handgun Violence Prevention Act of 1993 that required local chief law-enforcement officers to perform background checks on prospective handgun purchasers pending a national system. Scalia held that the federal government cannot circumvent its lack of a general police power by compelling the states' executive officers to administer federal schemes. The anti-commandeering doctrine was extended further in Murphy v. National Collegiate Athletic Association, 584 U.S. 453 (2018), where the Court struck down the Professional and Amateur Sports Protection Act of 1992, which had prohibited states from authorizing or licensing sports gambling. Justice Alito, writing for a 6-3 majority, held that the federal statute did not merely regulate private actors but affirmatively told states that they could not authorize a particular activity -- a form of commandeering of the state's legislative power that violated the Tenth Amendment even though PASPA did not require any state officer to take any affirmative action.

The second line of modern Tenth Amendment enforcement runs through judicially imposed limits on Congress's Commerce Clause authority. In United States v. Lopez, 514 U.S. 549 (1995), the Court held 5-4 in an opinion by Chief Justice Rehnquist that the Gun-Free School Zones Act of 1990 -- which made it a federal crime to possess a firearm in a school zone -- exceeded Congress's Commerce Clause power. Rehnquist identified three categories of activity Congress may regulate under the Commerce Clause: use of the channels of interstate commerce, the instrumentalities of interstate commerce or persons or things in interstate commerce, and activities that substantially affect interstate commerce. Possession of a gun near a school, Rehnquist held, did not qualify: it was a purely local, non-economic activity with no demonstrated substantial effect on interstate commerce. United States v. Morrison, 529 U.S. 598 (2000), applied the same framework to strike 5-4 the civil remedy provision of the Violence Against Women Act of 1994, which allowed victims of gender-motivated violence to sue their attackers in federal court. The Court found gender-motivated crime was not economic activity and rejected the aggregation argument that, taken in the aggregate, violence against women had substantial effects on commerce. In National Federation of Independent Business v. Sebelius, 567 U.S. 519 (2012), a majority of the Court held that the Affordable Care Act's individual mandate exceeded Commerce Clause power -- Congress could regulate commerce but could not compel individuals to enter a commercial market -- though Chief Justice Roberts, joined by Justices Ginsburg, Breyer, Sotomayor, and Kagan, upheld the mandate as a valid exercise of Congress's taxing power. The same decision's Medicaid expansion holding -- a 7-2 majority finding that conditioning all Medicaid funding on states' expansion of the program was unconstitutionally coercive under the Spending Clause -- added a further Tenth Amendment-adjacent limit on Congress's power to pressure states through conditional grants.

The Tenth Amendment's relationship to state sovereignty has generated recurring debates about the constitutional limits on federal power over state and local governments. In Garcia v. San Antonio Metropolitan Transit Authority, 469 U.S. 528 (1985), the Court overruled its earlier National League of Cities v. Usery, 426 U.S. 833 (1976), decision and held 5-4 that the Fair Labor Standards Act's minimum wage and overtime requirements applied to state and local government employees. The Garcia majority, written by Justice Blackmun, concluded that the political safeguards of federalism -- the structural features of Congress that give states representation and influence in the national legislative process -- provided a more reliable protection for state sovereignty than judicially policed substantive limits on federal power. This approach effectively withdrew the Tenth Amendment as a direct check on generally applicable federal statutes regulating the states as employers. The Court's subsequent decisions in New York, Printz, Lopez, and Morrison represent partial retreats from the Garcia approach, though the Court has not overruled Garcia or returned to the pre-Garcia framework of categorical limits on Congress's power to subject states to generally applicable federal regulations. The result is a layered federalism jurisprudence in which the anti-commandeering doctrine, limits on the Commerce and Taxing and Spending Clauses, and the political safeguards of federalism operate as overlapping but distinct constitutional constraints.

For the 2028 presidential election, the Tenth Amendment is central to several of the most contested domestic policy debates. Proposals for federal standards for voting -- including federal voter registration systems, federal early voting requirements, and federal ID standards -- raise Tenth Amendment questions about whether Congress can mandate state election administration practices. Proposals to expand or contract the ACA's Medicaid program implicate the coercion doctrine from NFIB v. Sebelius. Debates over federal immigration enforcement, including whether the federal government may compel local law enforcement to hold or inquire about immigration status, run directly through Printz's anti-commandeering rule. Climate and energy regulation involves ongoing questions about whether the federal government can impose emissions standards that effectively require states to redesign their energy grids. Marijuana legalization, now in place in a majority of states under state law while remaining a federal Schedule I controlled substance, sits at the fault line between federal Commerce Clause authority and state police power. The 2028 winner will shape the executive branch's posture on all of these conflicts and, through judicial appointments, the Supreme Court's future direction on the scope of the Tenth Amendment's structural constraints on federal power.