The Tenth Amendment to the Constitution, the last of the Bill of Rights adopted almost contemporaneously with the ratification of the Constitution itself, is frequently referred to as the “Reserved Powers” amendment. It declares:
“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.”
Some express the opinion that the Tenth Amendment has been honored more often in the breach, others that it has been trampled, still others that it is an anachronism. It is certainly true that many have detected in the juxtaposition of the Ninth and Tenth Amendments one of the great ambiguities of the Constitution — discerning a potential conflict between the unenumerated rights of individuals in the 9th and the unenumerated powers of the states in the 10th. Indeed, many of the most controversial Supreme Court decisions have revolved around precisely this point.
Perhaps the single most important point that can be advanced about the Tenth Amendment is that it is, in precise encapsulated form, a restatement of the fundamental character of our Constitution — its federalism. Our national government has been delegated certain powers and responsibilities; the states and the people retain all others.
For an interesting discussion of the jurisprudence concerning the Tenth Amendment, see the Government Printing Office version of the Analysis and Interpretation of the Constitution: Annotations of Cases Decided by the Supreme Court of the United States.