James Madison famously described the Tenth Amendment as "superfluous." Yet many today argue that the Tenth Amendment is quite important, indeed essential, to the establishment of federalism in the United States. By stating that all powers not delegated to the federal government are reserved by the states, the Tenth Amendment establishes and protects the role of state governments against federal incursions.

Accordingly, the Tenth Amendment has been at issue in many political disputes involving states rights. At various times, it has been cited by the Supreme Court to strike down legislation that were deemed to infringe on powers reserved by the states. For much of the twentieth century, the Tenth Amendment was not used as a vehicle for limiting the powers of the states by the Supreme Court. But many, especially conservatives who argue for more state control at the expense of the powers of the federal government, continue to cite the Tenth Amendment as evidence that the Founders meant to maintain a great deal of political power in the states. Conservatives in the Supreme Court in the late '90s and first decade of the twentieth century repeatedly interpreted the Tenth Amendment to restore, in their minds, the "balance the Framers designed." Many recent issues could potentially involve the Tenth Amendment, including marijuana laws, gun control legislation, and federal education programs.