McCulloch v. Maryland was a landmark U.S. Supreme Court decision under Chief Justice John Marshall that defined the scope of the U.S. Congress’s legislative power and how it relates to the powers of American state legislatures. The case established two important principles in constitutional law. First, the Constitution grants to Congress implied powers to implement the Constitution’s express powers to create a functional national government. Prior to the Supreme Court’s decision in McCulloch, the scope of the U.S. government’s authority was unclear Second, state action may not impede valid constitutional exercises of power by the federal government.