The 10th Amendment, like its counterpart, the 9th Amendment, had no real precedents in Anglo-American constitutional history. The prototype that most closely resembles the 10th Amendment was a precedent that the Federalists had explicitly rejected. The Articles of Confederation had included a provision that stated: “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.” The Federalists rejected this language because, under the new Constitution, each state would not retain all of its sovereignty, and the new federal government had deliberately been given more powers than those that had been delegated “expressly.”
Indeed, when the Constitutional Convention first submitted its new plan of government to Congress, it sent an accompanying letter that explained that it was impossible “to secure all rights of independent sovereignty to each [state], and yet provide for the interest and safety of all.” The Constitution therefore required the states to give up at least some of their previous sovereignty.
Antifederalists did not like this idea. During the ratification period, they claimed that the Constitution gave unlimited and unfettered power to the federal government. Federalists denied this charge and claimed that federal authority was clearly delineated and confined within the Constitution’s list of enumerated powers. As divergent as these two positions would seem, in one sense there was no difference at all between the two: the Antifederalists argued that a government of limited powers was what the Constitution should be, and the Federalists argued that a government of limited powers was what the Constitution already was. The 10th Amendment was therefore not a concession by the Federalists but rather a clarification. In the minds of the Federalists, it did not change the meaning of the Constitution.
This clarification was perhaps necessary, however, because the United States Constitution was creating a federal arrangement that was unlike anything that had ever preceded it. Part of the confusion and suspicion at this time arose because many people believed that sovereign (or supreme) power could not be divided into separate hands within the same territory. Alexander Hamilton had himself expressed this opinion in the Constitutional Convention: “Two sovereignties cannot coexist within the same limits.”
By the time Hamilton defended the Constitution in the New York Ratifying Convention, however, he had changed his tune. When another delegate had made the same claim about the impossibility of divided sovereignty, Hamilton replied: “This is curious sophistry.” That principle is true, he said, only when they are trying to rule over the same objects, and that was not the case with the United States Constitution. “The laws of the United States are supreme, as to all their proper, constitutional objects: the laws of the states are supreme in the same way.” Every imaginable power—except those that the Constitution delegated to the Federal Government and except those that it denied to the states (like printing paper money and impairing the obligations of contracts)—would be exercised by the sovereign power of the states. And when they exercised their legitimate powers, the states were supreme.