Dred Scott v. Sandford is recognized as one of the most controversial decisions in U.S. Supreme Court history, determining in 1857 that the Constitution did not recognize people of black African descent as American citizens, thereby denying them the rights and privileges reserved for citizens.^[15] This decision, regarded as one of the Court's most regrettable, centered around Dred Scott, an enslaved black individual who had lived in territories where slavery was illegal. Scott argued that his time in these territories entitled him to freedom. Nevertheless, by a 7–2 verdict, the Supreme Court ruled against him. Chief Justice Roger Taney wrote the majority opinion, asserting that African-descended individuals "were not intended to be included" as citizens in the Constitution, referencing historical laws to argue that a distinct separation was intended between white citizens and those they enslaved. The Court's decision also invalidated the Missouri Compromise, dismissing it as an overreach of Congressional authority regarding property rights of slaveholders.^[15]

The ruling, instead of quelling the growing dispute over slavery, only intensified the national divide on the issue.^[16] While the decision found favor among slaveholding states, it was vehemently opposed in the non-slaveholding states.^[17] The verdict stoked the fires of the national debate on slavery, significantly contributing to the tensions that led to the American Civil War. Just years after the decision, the Thirteenth and Fourteenth Amendments to the U.S. Constitution were ratified, respectively abolishing slavery and guaranteeing citizenship to all persons born or naturalized in the United States.

The aftermath of Dred Scott v. Sandford saw its ruling overshadowed by larger political movements and events. Historians largely view the decision as exacerbating the divisions that would culminate in the Civil War.^[18] During the 1860 U.S. elections, the newly-formed Republican Party, advocating abolition, countered the Supreme Court's verdict, suggesting it was influenced by bias and exceeded its jurisdiction. Their candidate, Abraham Lincoln, contested the court's findings and declared he would limit slavery's expansion. Lincoln's election is commonly seen as the trigger for Southern states' secession, marking the onset of the American Civil War.^[19]