Federalism is a system of dual sovereignty. The Constitution provides a federal system in which power is divided between the federal government and state governments. This is what James Madison called a “double security” in Federalist No. 51. The Constitution specifically lists the powers of the Legislative Branch in Article I, the powers of the Executive Branch in Article II, and the powers of the Judicial Branch in Article III. Under a theory of limited government, the federal government is assumed to have no powers other than those listed. The Tenth Amendment confirms that the states and the people retain powers not delegated to the federal government.
Under our federal system, the federal and state governments have reserved and concurrent powers. As the Founders anticipated, the power struggles that sometimes occur between the two types of governments serve as part of the system of checks and balances, designed to prevent an abuse of power and protect individual rights.
Supreme Court cases that have involved issues of federalism include McCulloch v. Maryland (1819), Gibbons v. Ogden (1824), South Dakota v. Dole (1987), United States v. Lopez (1995) and United States v. Morrison (2000). Many of these cases hinged on the interpretation of the Commerce Clause.
The Fourteenth Amendment changed federalism by incorporating, for the first time, a check on state power by the national government. Critics say it all but did away with state sovereignty, while supporters say that the amendment was vital to protecting individuals from abuses by state governments. The Seventeenth Amendment also changed federalism by providing for direct election of Senators.