In 1857, Dred Scott (1795-1858) a slave in Virginia sued for his
freedom after becoming a resident of Missouri, a free state. The case
went to the Supreme Court. In Dred Scott v Sanford
, the court
held that Blacks could not be citizens of the United States of
America, independent of whether they are citizens of any given state.
As such, Blacks could not sue in a Federal court.
This dual-citizenship doctrine was as wide-reaching as the later
doctrine of seperate-but-equal and was used after the Civil War to
strip away those rights that would be won by Blacks after the war.