The Author analyses a famous debate in the United States between Senator Daniel Webster of Massachusetts and Senator Robert Y. Hayne of South Carolina that took place on January 19–27, 1830 on the topic of protectionist tariffs. These constitutional debate gave fateful utterance to the differing understandings of the nature of the American Union that had come to predominate in the North and the South. To Webster the Union was the indivisible expression of one nation of people, but to Hayne was the voluntary compact among sovereign states. The Author presents Hayne’s argument for states’ right to nullify, or invalidate, any federal law which that state has deemed unconstitutional, and Webster response for Supreme Court jurisdiction. Their classic expositions of their respective views framed the political conflicts that culminated at last in the secession of the Southern states and war between advocates of Union and champions of Confederacy.