The requirements of the U.S. Constitution are often assumed to be either clear or defined by the judiciary through interpretation, or both. Examination of the nullification crisis of 1833 indicates that this view of the Constitution is misleading. The nullification crisis provoked three competing visions of the appropriate understanding of federalism in the context of textual ambiguity and judicial activity. The subsequent development of federalism was determined by that political conflict and compromise. The nullification controversy provides an important example of the openness of constitutional norms, the significance of political debate in the shaping of constitutional meaning, and the complexity of antebellum political thought.