Robert Young Hayne was an American lawyer, planter and politician. He served in the United States Senate from 1823 to 1832, as Governor of South Carolina 1832โ1834, and as Mayor of Charleston 1836โ1837. As Senator and Governor, he was a leading figure in the Nullification Crisis and, along with John C. Calhoun and James Hamilton Jr., a vocal proponent of the doctrines of states' rights, compact theory, and nullification; his 1830 debate in the Senate with Daniel Webster is considered a defining episode in the constitutional crisis which precipitated the American Civil War.