The Tenth Amendment - the powers not delegated to the US by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the People. If Congress passes a generally applicable law, the fact that the regulation affects the states has virtually no practical significance and the Tenth Amendment never comes into play. But the Tenth Amendment does prevent Congress from interfering in certain ways with a state's law-making processes. Congress may not simply "commandeer the legislative process of the states by directly compelling them to enact and enforce a federal regulatory program." (New York v. United States)