Tenth Amendment

The Tenth Amendment states the basic architecture of American federalism: 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. It is a statement of principle — that the federal government possesses only the powers the Constitution grants it, and everything else remains with the states or the citizens.

The amendment was the Anti-Federalists' price for ratification, a reassurance that the new national government would not swallow the states whole. For much of the nineteenth century it served as a rallying text for states' rights, invoked in defense of slavery, nullification, and later segregation. Its meaning has swung with the balance of power between Washington and the states across the whole of American history.

In the modern era the Court has used it to draw real limits on federal authority. In New York v. United States (1992) and Printz v. United States (1997), it held that the federal government cannot commandeer states or their officials to carry out federal programs — the anti-commandeering doctrine. More recently the amendment has featured in disputes over health care, marijuana laws, and immigration enforcement, a reminder that the oldest question in American government — who decides — is never fully settled.