The last amendment in the Bill of Rights states the basic design principle behind all of them: the federal government only has the powers it’s actually been given. Everything else belongs to the states, or to the people directly.
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.
Tenth Amendment, U.S. Constitution
The text
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.
Spelling and punctuation as transcribed by the National Archives.
The theory behind federalism
The Tenth Amendment is often called the states’-rights amendment, though that shorthand undersells its actual structure: it reserves power to the states and to the people, not to states alone. It restates a principle already implicit in Article I’s grant of specifically “enumerated” powers to Congress — the federal government was designed from the outset to have limited, listed powers, not a general grant of authority to legislate on anything.
In practice, the line between federal and state power has moved considerably since 1791, largely because of how broadly courts have interpreted two other constitutional provisions: the Commerce Clause and the Necessary and Proper Clause. The bigger those two clauses are read, the smaller the practical space the Tenth Amendment protects.
Worth knowing
The Supreme Court has used the Tenth Amendment to strike down federal laws in a narrower but real category of cases: those that try to directly commandeer state governments into administering a federal program. New York v. United States (1992) and Printz v. United States (1997) both held that Congress can’t force state legislatures or state officials to implement or enforce federal law.
Why it still matters
Nearly every dispute over whether an issue belongs to Congress or to state legislatures — marijuana legalization, minimum wage floors, environmental regulation, more recently pandemic-era mandates — eventually runs into the same underlying question this amendment poses: was this ever a federal power to begin with, or was it reserved to the states all along?
Worth knowing
A common misconception is that the Tenth Amendment can be invoked to block any federal action a state disagrees with. It can’t — the amendment only reserves powers that were never delegated to the federal government in the first place. Once a power genuinely falls within one of the Constitution’s federal grants, the Tenth Amendment doesn’t create a separate veto for states to override it.
