Dred Scott was an African-American slave who unsuccessfully sued for his freedom in the Supreme Court case Dred Scott vs. Sandford. The Supreme Court's decision against Scott increased tensions between pro-slavery and anti-slavery factions in the United States.
Born into slavery in Virginia in the late 18th century, Scott worked in Virginia, Alabama and Missouri before his owners sold him to Dr. John Emerson. As a doctor in the U.S. Army, Emerson moved around often, and he took Scott with him on his travels. For four years, he lived in Illinois and the Wisconsin Territory. In both of these areas, slavery was illegal. Instead of staying in the free states or filing a petition for freedom, Scott traveled with his wife to Louisiana, where Emerson had gotten married.
After Emerson died, his widow ordered Scott to begin working for another Army officer, but he did not wish to do so. After Mrs. Emerson refused to allow Scott to buy his and his wife's freedom, he went to the courts in 1846, arguing his residence in a free state made him a free man. After losing his first attempt on a technicality, Scott won his second case. The Missouri Supreme Court overturned this decision, and a federal court agreed with the ruling.
Scott appealed his case to the U.S. Supreme Court, which issued an opinion in 1857. This opinion held that slaves were not citizens and that the Missouri Compromise of 1820, which outlawed slavery in certain areas, was unconstitutional.