On March 6, 1857, the United States Supreme Court rules on the case of Dred Scott v. Sandford, effectively declaring that blacks, slaves or freemen, could not be U.S. citizens. Furthermore, it ruled that the Missouri Compromise of 1820, which ensured pro- and anti-slavery states would be added to the union in pairs to preserve balance, was unconstitutional. The decision inflamed and widened the differences between pro- and anti-slavery Americans, ultimately leading to the Civil War.
Source: tatoeba (12243668)