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The Tenth Amendment (Amendment X) to the United States Constitution, which is part of the Bill of Rights, was ratified on December 15, 1791. It expresses the principle of federalism and states' rights, which strictly supports the entire plan of the original Constitution for the United States of America, by stating that the federal government possesses only those powers delegated to it by the United States Constitution. All remaining powers are reserved for the states or the people.
 
The amendment was proposed by the 1st United States Congress in 1789 during its first term following the adoption of the Constitution. It was considered by many members as a prerequisite to many state ratifications of the Constitution and particularly to satisfy demands of Anti-Federalists who opposed the creation of a stronger federal government.

The drafters of this amendment had two purposes in mind: first, as a necessary rule of construction; and second, as a reaffirmation of the nature of federalism.

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