The Tenth Amendment to the United States Constitution, a part of the Bill of Rights, was ratified on December 15, 1791. It expresses the principle of federalism, also known as states' rights, by stating that the federal government has only those powers delegated to it by the Constitution, and that all other powers not forbidden to the states by the Constitution are reserved to each state.
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 before they would ratify the Constitution, and particularly to satisfy demands of Anti-Federalists, who opposed the creation of a stronger federal government.
The purpose of this amendment is to clarify how the federal government's powers should be interpreted and to reaffirm the nature of federalism.
Justices and commentators have publicly wondered whether the Tenth Amendment retains any legal significance.
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 similar to Article II of the Articles of Confederation:
Each state retains its sovereignty, freedom, and independence, and every power, jurisdiction, and right, which is not by this Confederation expressly delegated to the United States, in Congress assembled.
After the Constitution was ratified, South Carolina Representative Thomas Tudor Tucker and Massachusetts Representative Elbridge Gerry separately proposed similar amendments limiting the federal government to powers "expressly" delegated, which would have denied implied powers. James Madison opposed the amendments, stating that "it was impossible to confine a Government to the exercise of express powers; there must necessarily be admitted powers by implication, unless the Constitution descended to recount every minutia." When a vote on this version of the amendment with "expressly delegated" was defeated, Connecticut Representative Roger Sherman drafted the Tenth Amendment in its ratified form, omitting "expressly". Sherman's language allowed for an expansive reading of the powers implied by the Necessary and Proper Clause.
When James Madison introduced the Tenth Amendment in Congress, he explained that many states were eager to ratify this amendment, despite critics who deemed the amendment superfluous or unnecessary:
I find, from looking into the amendments proposed by the State conventions, that several are particularly anxious that it should be declared in the Constitution, that the powers not therein delegated should be reserved to the several States. Perhaps words which may define this more precisely than the whole of the instrument now does, may be considered as superfluous. I admit they may be deemed unnecessary: but there can be no harm in making such a declaration, if gentlemen will allow that the fact is as stated. I am sure I understand it, and therefore propose it.
The states ratified the Tenth Amendment, declining to signal that there are unenumerated powers in addition to unenumerated rights. The amendment rendered unambiguous what had previously been at most a mere suggestion or an implication.
The phrase "... or to the people" was handwritten by the clerk of the Senate as the Bill of Rights circulated between the two Houses of Congress.