The Tenth Amendment to the U.S. Constitution states that 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 emphasizes the principle of federalism, which means the federal government only has the powers explicitly given to it by the Constitution, and all other powers are left to the states or the people. The Tenth Amendment was ratified on December 15, 1791, as part of the Bill of Rights and serves to limit federal power and affirm states' rights and individual liberty.
