McDuffie, together with South Carolina statesman John C. Calhoun, developed the doctrine of "nullification", which postulated that a state had the right to nullify a federal law with which it disagreed. This doctrine was put to a test in 1832. South Carolina passed the Ordinance of Nullification, and President Andrew Jackson threatened to send troops to the state to enforce the tariff. Edgefieldians, like most South Carolinians, reacted violently to the President's threats. Militia units were called up and the state braced for war. A national crisis was averted only by a last minute compromise that gradually reduced the tariffs.