What was the dread scout desicion

A Missouri slave sued for his freedom, claiming that his four year stay in the northern portion of the Louisiana Territory made free land by the Missouri Compromise had made him a free man. The U. S, Supreme Court decided he couldn't sue in federal court because he was property, not a citizen.

Dredd Scott

Explanation:

It was a court case that said no African-American, slave or free, could claim U. S. citizenship.