Political debate over slavery in the territories became so heated in part because the Constitution lacked precision on the issue. In 1857, in the case of Dred Scott v. Sandford, the Supreme Court announced its understanding of the meaning of the Constitution regarding slavery in the territories. The Court’s decision demonstrated that it enjoyed no special immunity from the sectional and partisan passions that were convulsing the land.

In 1833, an army doctor bought the slave Dred Scott in St. Louis, Missouri, and took him as his personal servant to Fort Armstrong, Illinois, and then to Fort Snelling in Wisconsin Territory. Back in St. Louis in 1846, Scott, with the help of white friends, sued to prove that he and his family were legally entitled to their freedom. Scott argued that living in Illinois, a free state, and Wisconsin, a free territory, had made his family free and that they remained free even after returning to Missouri, a slave state.

In 1857, Chief Justice Roger B. Taney, who hated Republicans and detested racial equality, wrote the Court’s Dred Scott decision. The Court explicitly declared the Missouri Compromise unconstitutional, even though it had already been voided by the Kansas-Nebraska Act.

The Taney Court’s extreme proslavery decision outraged Republicans. By denying the federal government the right to exclude slavery in the territories, it cut the legs out from under the Republican Party. Moreover, as the New York Tribune lamented, the decision cleared the way for “all our Territories … to be ripened into Slave States.” Particularly frightening to African Americans in the North was the Court’s declaration that free blacks were not citizens and had no rights.

In a seven-to-two decision, the Court validated an extreme statement of the South’s territorial rights. John C. Calhoun’s claim that Congress had no authority to exclude slavery became the law of the land. White Southerners cheered, but the Dred Scott decision actually strengthened the young Republican Party. Indeed, that “outrageous” decision, one Republican argued, was “the best thing that could have happened,” for it provided powerful evidence of the Republicans’ claim that a hostile Slave Power conspired against northern liberties.