After reading the Supreme Court's Dread Scott Decision, this is the summary I came up with:
In 1857 a controversial supreme court case was about to be concluded: the
Scott v. Sandford case. This case brought to light issues about the constitutionality of the Missouri Compromise and led to many focusing on the controversial topic of white citizenship. Roger Taney, the Supreme Court Justice at the time, addressed black citizenship, specifically the legality of making someone who was a slave a citizen, and that Dred Scott was not an American citizen, so didn't really have the right to sue. Due to this, Taney declared the court case unconstitutional. Taney then proceeded to declare the Missouri Compromise unconstitutional. This made it so Dred Scott had no hope of becoming a free man.
My source for this:
Supreme Court Dred Scott Decision