What was the dred Scott case and what did the decision mean for the African Americans

The sentence in the Dred Scott v. John F. A. Sandford case of March 6, 1857, is one of the most infamous sentences of the US Supreme Court. The judges (7-2) argued that African Americans were not American citizens and then could not sue other people in court; that the 1820 Missouri Compromise that had declared free of slavery all states west of Missouri and north of latitute 36°30′, was unconstitutional; and that slave Dred Scott could not recover his freedom just because he had lived in a free state before. It is considered the worst sentence in judicial American history.