In 1857, the political equilibrium of the United States of
America was rocked by the decision of the United States Supreme
Court in
Dred Scott v Sandford. That decision called into
question the constitutionality of the so-called Missouri Compromise
(prohibiting slavery in the northern continental US with the
exception of Missouri), which had been a key part of the strategy
to contain the spread of slavery, rather than to eliminate it, a
challenge which the then current political wisdom judged to be
unachievable.
Landmark slavery case a trigger for American Civil
War
Dred Scott was a slave who had been sold to a master who took
him to free territory in modern-day Minnesota, but then back to
Missouri, where Scott tried to sue for his freedom. Unexpectedly,
the Court held that Scott was property and not a citizen at all,
and thus could not sue (or be sued) in the courts.