The case is Dred Scott vs. Sanford. Dred Scott had been a slave in Missouri, but later was moved by his master to Illinois, a free state, and later to part of the Louisiana territory above the Missouri Compromise line where slavery was illegal. He later was returned to Missouri, where slavery was legal, and subsequently sued, claiming he could not be a slave since he had been made a free man by living in an area where he could not legally be a slave.
The U.S. Supreme Court ruled 7-2 against Scott. Chief Justice Roger Taney wrote the majority opinion in which he stated that Scott was not a citizen of the United States since no person born a slave could be a citizen of the United States under Article III of the Constitution. Since he was not a citizen, he had no standing to bring suit. Taney further ruled that since slaves were personal property of their owner, they could not be taken from their owner without due process, as provided for in the Fifth Amendment to the Constitution. That being the case, the Missouri Compromise, which outlawed slavery above the compromise line, was unconstitutional. Congress had previously abolished the compromise in favor of popular sovereignty; however the Scott decision apparently held that slavery could be legal in any U.S. state or territory.
The Constitution of the United States recognises slaves as property, and pledges the Federal Government to protect it. And Congress cannot exercise any more authority over property of that description than it may constitutionally exercise over property of any other kind.
The act of Congress, therefore, prohibiting a citizen of the United States from taking with him his slaves when he removes to the Territory in question to reside is an exercise of authority over private property which is not warranted by the Constitution, and the removal of the plaintiff by his owner to that Territory gave him no title to freedom.
In the Dred Scott decision, 1857 the Supreme Court ruled that Black people were not citizens of the United States and therefore could not petition the Court. This decision established the principle that national legislation could not limit the spread of slavery into the territories. The Dred Scott decision repealed the Northwest Ordinance of 1787 and the Missouri Compromise of 1820.