The Dred Scott decision, delivered by the Supreme Court in 1857, ruled that Dred Scott, an enslaved African American, was not entitled to freedom despite having lived in free territories.

The Court declared that slavery was legal in all U.S. territories, effectively overturning the Missouri Compromise, which had attempted to limit the spread of slavery. This ruling exacerbated tensions between the North and South, further polarizing the nation on the issue of slavery and contributing to the conditions that led to the Civil War. It is widely regarded as one of the most infamous Supreme Court decisions in American history.