Dred Scott decision, formally Dred Scott v. John F.A. Sandford, legal case in which the U.S. Supreme Court on March 6, 1857, ruled (7–2) that a slave (Dred Scott) who had resided in a free state and territory (where slavery was prohibited) was not thereby entitled to his freedom; that African Americans were not and could never be citizens of the United States; and that the Missouri Compromise (1820), which had declared free all territories west of Missouri and north of latitude 36°30′, was unconstitutional. The decision added fuel to the sectional controversy and pushed the country closer to civil war.