Amendment X (the Tenth Amendment) of the United States Constitution, which is part of the Bill of Rights, states:
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 Tenth Amendment is generally recognized to be a truism. In United States v. Sprague the Supreme Court noted that the amendment "added nothing to the instrument [the Constitution] as originally ratified."

See also


9th Amendment United States Bill of Rights
United States Constitution
11th Amendment