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.
Can you be fired for using medical marijuana? Just ask this guy.
Wikipedia 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 Congress in 1789 during its first term following the Constitutional Convention and ratification of the Constitution. It was considered by many members as a prerequisite of such ratification particularly to satisfy demands by the Anti-Federalism movement that opposed the creation of a stronger U.S. federal government.
In drafting this amendment, its framers had two purposes in mind: first, as a necessary rule of construction; and second, as a reaffirmation of the nature of the federal system of freedom.