Federal power is limited. If there is no interstate commerce involved and the matter does not involve individual rights under the Constitution, the states have the right to control their affairs. The federal government also has very limited authority to commandeer state personnel to enforce federal law. If the federal government wants to regulate an area that is reserved to the states, or does not have the funds to take a specific action with a federal agency, it can provide the states with a financial incentive to encourage them to follow federal guidelines. When Congress wanted the states to pass laws requiring people in cars to wear seatbelts, it told the states to pass seatbelt laws or lose some of their federal highway construction money. The Medicaid program is a state–federal partnership in which the federal government controls actions of state personnel through restrictions on the federal matching money.