In March of 1857, the U.S. Supreme Court declared that all blacks, whether they were free or slaves, were not citizens of the country. Abolitionist Frederick Douglass said the decision, which was a bad one, would bring slavery to the attention of the nation. He said the decision would be a step toward eliminating slavery, and he was right. Because of that decision, Abraham Lincoln was nominated and elected President, which led to the South's secession from the Union. That led to the Civil War, which ultimately freed the slaves. For more information, visit this PBS site.
Dred Scott Case