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NARRATOR: In 1828, Congress passed a tariff to protect American manufacturers against cheaper foreign imports. This protective tariff almost brought the country to the brink of Civil War.

- The idea of a tariff-- it's quite simple, really. It is a duty on a foreign good. Let's say the English blanket would cost $10. The Americans could only make it for $12, and so there's no way they could compete. Well if you slap on a 50% tariff, suddenly that British blanket costs $15. The American blanket costs $12, and now you've helped out domestic manufacturing.

NARRATOR: The tariff of 1828 appealed to manufacturers, and the heart of American manufacturing was in the North-- in New England's growing textile industry. But Southerners hated the tariff. They called it the Tariff of Abominations.

JOHN STEELE GORDON: Well the South was not a manufacturer. The South exported goods, and then had to import the manufactured goods. And so the South wanted low tariffs, so they could buy those goods more cheaply.

NARRATOR: The vice president, at the time, was John C. Calhoun from South Carolina. He championed the fight against the tariff.

MATTHEW WARSHAUER: And in 1828, as vice president of the United States-- but anonymously-- John Calhoun writes what becomes known as the South Carolina Exposition and Protest. And he says a couple of key things. Number one, the tariff is unconstitutional. And the reason that the tariff is unconstitutional, in Calhoun's eyes, is that it helps the North at the expense of the South. And here is where Calhoun, as a political theorist, really reveals some of his brilliance. He figured out a way that a state can constitutionally and legally nullify-- void-- a federal law.

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NARRATOR: When Congress agreed to lower the tariff in 1832, the South Carolina contingent, that wanted it eliminated, was unsatisfied. It passed an ordinance of nullification, which declared the federal tariff did not exist within state boundaries.

MATTHEW WARSHAUER: The trump card for Calhoun-- and what makes his theory of nullification that much more radical-- is that he says, if a state does, in fact, determine that a law is unconstitutional, and they nullify that law, if the federal government attempts to force that law upon the state, the state has the right to secede-- to leave the Union.

NARRATOR: President Andrew Jackson was furious. He railed against nullification, and quietly began to prepare the army for war. Behind closed doors, he told friends He would invade South Carolina and hang its leaders if the state did not back down.

In 1833, Jackson got Congress to pass the Force Bill, authorizing him to use troops to enforce federal tariff laws, if necessary. That same day, Senator Henry Clay engineered a compromise to gradually reduce the tariff enough to placate South Carolina. The bill squeaked through Congress, preventing a Civil War. The South Carolina legislature met and withdrew its nullification of the tariff, but in a final act of defiance, abolished Jackson's Force Bill in their state.

MATTHEW WARSHAUER: Nullification, as a theory, never rears its head again. No one ever attempts to nullify federal law again. But it does not kill the idea of secession. Secession continues to roll around, and as we know, there's an attempt to secede from the Union in 1861 by a number of Southern states.