This article is an original work of scholarship in several respects. As the title suggests, it presents a novel interpretation of the “original understanding” of the Constitution, which I call the inherent national sovereignty theory. This theory viewed the national government as a sovereign government and Congress as a sovereign legislature imbued with the countless legislative powers that sovereign legislatures possesses. The sources of this understanding are themselves original. The article is based in part on a systematic analysis of the political debates relating to politically defining actions of the federal government in this nation’s early history: the incorporation of the First Bank of the United States in 1791; the decision to allow the bank’s charter to expire in 1811; and the decision to incorporate the Second Bank of the United States in 1816. No one has previously engaged in a systematic constitutional analysis of these political debates. I have found that bank proponents asserted Congress’s inherent sovereign legislative power to explain Congress’s authority to incorporate the First and Second Banks. The article also presents a novel interpretation of the Supreme Court’s decision in McCulloch v. Maryland, which upheld the constitutionality of the Second Bank of the United States in an opinion that many scholars believe to be the most important in the Court’s history. Viewed for the first time within the context of over twenty years of political/constitutional debates relating to the First and Second Banks, this article shows that the opposing lawyers in this case argued the inherent national sovereignty theory and the strict construction, states’ rights theory of the Constitution popular among today’s conservatives. It shows that Chief Justice John Marshall’s opinion for a unanimous Court upheld the constitutionality of the Second Bank by affirming Congress’s inherent sovereign legislative powers. The article also shows that Congress based other actions, and the Court upheld these actions in other cases, by affirming the inherent national sovereignty theory of the Constitution. This article is original in other significant ways. In identifying actions taken by the federal government pursuant to a theory of inherent national sovereignty, the article presents a novel rebuttal to the current “new originalists” who argue that the original understanding of the Constitution posited a strict construction, states’ rights-oriented, and fixed understanding of limited powers. The McCulloch Court expressly rejected this theory. More broadly, this article presents a discussion of the original understandings of the Constitution within the constitutional/political process of governing. In this context, proponents of inherent national sovereignty understood the Constitution as a dynamically-evolving framework of government whose meaning would develop over time through the political process and by the specific actions taken by Congress and the executive branch of the federal government. Many of the leading political actors in the nation’s founding generation considered the constitutional/political process itself as an authoritative means of constitutional construction. They regarded congressional actions as having precedential authority in deciding questions of constitutional construction. Consequently, political practice gave meaning to the text of the Constitution. The Constitution was to be constructed by the political branches of the federal government, primarily by Congress, through the dynamic process of governing. The Court’s role was to uphold the constitutionality of congressional actions to meet the nation’s needs unless Congress exercised a power that was expressly prohibited or explicitly reserved to the states or to the people. Inherent national sovereignty constitutionalism is fundamentally different from today’s understanding of the Constitution, of the constitutional/political process, and of the relationships of the branches of government within the constitutional structure. It entrusts much greater autonomy to Congress and the executive to govern and much greater authoritativeness to Congress’s interpretation of the Constitution in its function to make law and public policy than our system today allows. It envisions a more modest role for the judiciary in reviewing Congress’s legislative actions and the policies they entail. This theory centers policy making in the political branches of the government rather than in the Supreme Court where it currently exists. Moreover, inherent national sovereignty constitutionalism relegates constitutional interpretation in making political decisions to a less important role and requires decision makers to justify their actions on their practical merits instead of the Constitution’s meaning. In short, inherent national sovereignty constitutionalism presents a fundamentally different understanding of the way government should function under the Constitution.