Dred Scott was a slave, taken by his master, Dr. Emerson, from the State of Missouri to the free State of Illinois; then to Fort Snelling, near the present site of St. Paul, Minnesota. There, he married with his master's consent, and was taken back to Missouri in 1838, where with his wife and children he was sold to John P.A. Sanford. Dred Scott sued for the liberty of himself and family, alleging that his residence in a free State and in a Territory from which slavery was excluded by the Missouri Compromise, established his freedom.
Both the Circuit and the Supreme Court of the United States decided against the freedom of Scott, a decision that would united the people of the North in a more determined opposition to the extension of slavery.