13. The Dred Scott Decision (1857)
The Dred Scott v. Sandford decision of 1857 was a landmark Supreme Court ruling that denied African Americans, whether enslaved or free, the status of U.S. citizenship, thereby prohibiting them from suing in federal court. Additionally, the Court declared that Congress lacked the authority to prohibit slavery in the territories, effectively nullifying the Missouri Compromise (history.com). This ruling intensified Northern opposition and emboldened the South, deepening national divisions over slavery.
