Final answer:
The U.S. Supreme Court ruled in the case of Dred Scott v. Sandford that slavery was permitted in U.S. territories and that slaves were not U.S. citizens.
Step-by-step explanation:
The correct answer is Dred Scott v. Sandford. This 1857 federal court case was significant in the lead-up to the American Civil War. The U.S. Supreme Court ruled that slavery was permitted in U.S. territories and that slaves were not U.S. citizens. The decision further deepened the divide between pro-slavery and anti-slavery forces in the country.
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