What is the Tenth Amendment?

The Tenth Amendment is the final amendment in the Bill of Rights and reserves to the states or the people any powers not delegated to the federal government and not prohibited to the states. Its full text reads: 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. James Madison drafted the language and the First Congress proposed it in September 1789. It was ratified along with the other nine amendments of the Bill of Rights on December 15, 1791.

The amendment was added in response to Anti-Federalist concerns that the new federal government would absorb all governmental power and leave the states as empty shells. The Articles of Confederation had explicitly stated that each state retained every power not expressly delegated to the United States, and Anti-Federalists during the ratification debates demanded a similar provision in the new Constitution.

The Tenth Amendment is sometimes called the truism amendment because it makes explicit what was already implicit in the Constitution's structure of enumerated powers. Federal authority comes only from specific grants in the text; everything else is reserved to states or to the people. The Supreme Court has alternately read the amendment as a reminder of structural limits and as an independent constraint on federal power. In United States v. Darby in 1941, Justice Harlan Stone wrote that the amendment states but a truism that all is retained which has not been surrendered.

More recently, in New York v. United States in 1992 and Printz v. United States in 1997, the Court treated it as a real limit, ruling that the federal government cannot commandeer state legislatures or state officers to enforce federal regulatory programs. NFIB v. Sebelius in 2012 used the principle to limit federal power to coerce state Medicaid expansion.

Reserved state powers include most criminal law, most family law, most education, professional licensing, real property rules, traffic laws, and elections. The amendment also reserves powers to the people, a clause invoked in arguments about unenumerated rights and direct popular action like state constitutional initiatives. The amendment thus protects both vertical separation of powers between federal and state governments and the broader principle that government holds only the powers the people have granted.