What made dred scott famous?

Answer 1

The astonishing conclusion by the Chief Justice that slavery was legal in every state of the Union, because the Constitution declared that a man's property was sacred, and the Founding Fathers would have included slaves in their definition of property.

Answer 2

Applied for his freedom after living on free soil for some years and then returning to slave country.

The local judges had not dealt with this kind of application before, and that is why it reached the Supreme Court.

Their decision was highly controversial. It divided the nation more sharply and brought war closer.