Reserved powers are powers retained by the states under the Tenth Amendment. The amendment says: 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. Reserved powers are the states' share of authority. They are the default. If the Constitution does not give a power to the federal government, the states keep it.

Reserved powers are broad. They include police power, education, health, safety, and welfare. States regulate marriage, divorce, property, and contracts. They run schools and prisons. They license doctors, lawyers, and drivers. The federal government has no general police power. It can only regulate areas the Constitution grants it. That is the difference. The federal government is limited. The states are general.

Examples of reserved powers

• Education: states run public schools.
• Health: states regulate hospitals and insurance.
• Safety: states set fire and building codes.
• Welfare: states administer many programs.
• Marriage and divorce: states set family law.

Reserved powers are not absolute. The federal government can preempt state laws in areas of federal authority. It can attach conditions to federal funding. It can use the Commerce Clause to regulate activities that affect interstate commerce. The line between reserved and federal power is contested. The Supreme Court decides where it lies. Cases like United States v. Lopez and NFIB v. Sebelius have limited federal power. Others have expanded it. The Tenth Amendment is a reminder that the states are not just administrative units. They are sovereign governments. They have their own constitutions, legislatures, and courts. They are laboratories of democracy. They are closer to the people. Reserved powers protect that role. They are a check on federal power. They are a guarantee of local control.