Meaning of the Tenth Amendment
Tenth Amendment made the Enumerated Powers structure explicit
As with the rest of the federal Bill of Rights, the Tenth Amendment did not change or modify the Constitution that was ratified by the states two years earlier. The Tenth Amendment simply made explicit what was already implicit in the logic of the Constitution. If a power was not delegated to the federal government via the Constitution and its enumerated powers, that power was reserved to the states (or to the people, subject to their respective state constitutions).
Despite being superfluous and unnecessary, Thomas Jefferson considered the Tenth Amendment the “foundation” of the Constitution since the principle of the Tenth Amendment underpins the entire logic and meaning of the Constitution. The thinking was, why not make what’s vitally important to the meaning of the Constitution explicit rather than leave it implicit?
The Tenth Amendment was a carryover from the Articles of Confederation and Perpetual Union. Article 2 said, “Each state retains its sovereignty, freedom, and independence, and every power, jurisdiction, and right, which is not by this Confederation expressly delegated.”
Tenth Amendment demanded by Anti-Federalists in the State Ratifying Conventions
The Anti-Federalists in the state ratifying conventions, who feared the federal government would become a centralized government with unlimited power (like it is today), demanded additional guarantees that the federal government would remain federal and would limit itself to its delegated, Enumerated Powers. In ratifying the Constitution, most states submitted their own proposed amendments for what would become the federal Bill of Rights. First on these lists was language similar to that of the eventual Tenth Amendment. Below are samples of that language from the ratifying documents of Massachusetts, Virginia and North Carolina:
Massachusetts’ proposed state sovereignty amendment
Massachusetts: “First, That it be explicitly declared that all Powers not expressly delegated by the aforesaid Constitution are reserved to the several States to be by them exercised.”
Virginia’s proposed state sovereignty amendment
Virginia: “1st. That each state in the Union shall respectively retain every power, jurisdiction, and right, which is not by this Constitution delegated to the Congress of the United States, or to the departments of the federal government.”
North Carolina’s proposed state sovereignty amendment
North Carolina: “1. Each state in the Union shall respectively retain every power, jurisdiction, and right, which is not by this Constitution delegated to the Congress of the United States, or to the departments of the general government; nor shall the said Congress, nor any department of the said government, exercise any act of authority over any individual in any of the said states, but such as can be justified under some power particularly given in this Constitution; but the said Constitution shall be considered at all times a solemn Instrument, defining the extent of their authority, and the limits of which they cannot rightfully in any instance exceed.”
United States Constitution – Tenth Amendment
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.