Akhil Reed Amar, Yale Law School professor, argues that political parties, though absent from the constitutional text, have shaped American constitutional practice as thoroughly as any written clause. He opens with Madison's warning about factions in Federalist 10, then turns to the original electoral college design, where the runner-up became vice president, and shows how that rule nearly broke the republic in the Adams-Jefferson contests of 1796 and 1800. The lecture walks through the Twelfth Amendment's rebuilding of presidential selection around a two-party system, then reads later amendments, the antislavery Reconstruction measures, women's suffrage, and the twenty-second and twenty-fifth, as artifacts of partisan practice rather than abstract principle. Chapters move chronologically from the founding through Reconstruction to the twentieth century, making the case that the unwritten constitution of party politics has steadily rewritten the written one.