What are reserved powers?

Reserved powers are the powers not given to the federal government and not denied to the states by the Constitution, which the Tenth Amendment reserves to the states or to the people. Ratified on December 15, 1791 as part of the Bill of Rights, 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. The amendment was added to reassure Anti-Federalists during ratification that the new federal government would not absorb all governmental authority. James Madison drafted the language, and similar provisions had appeared in the Virginia Declaration of Rights of 1776 and the Articles of Confederation.

Reserved powers cover most of daily life. States define and prosecute the great majority of crimes, including murder, theft, assault, and drug offenses. They run public schools, license doctors, lawyers, teachers, and contractors, and set rules for marriage, divorce, child custody, and adoption. They write traffic laws, manage real property, regulate professions, and oversee insurance, banking, and corporations. They run state courts and most local police departments. They tax incomes and sales separately from the federal government, and they administer programs like Medicaid in partnership with federal funding. Each state has its own constitution, legislature, governor, and judiciary, and within constitutional limits each may organize its government as it chooses.

The doctrine of reserved powers has shaped major Supreme Court rulings. In New York v. United States in 1992 and Printz v. United States in 1997, the Court held that the federal government cannot commandeer state legislatures or state officers to enforce federal regulatory programs. In NFIB v. Sebelius in 2012, the Court held that Congress could not coerce states into expanding Medicaid by threatening to revoke all existing Medicaid funding. These rulings rest on the principle that reserved powers carry real meaning and impose real limits on Washington.

Reserved powers do not make states sovereign in the international sense. They cannot make treaties, coin money, declare war, or impair contracts. But within the wide range left to them, fifty states can experiment with different approaches, producing significant variation in tax rates, criminal sentencing, education policy, and election rules.