On March 6th 1857 the United States Supreme Court issued a decision known as the "Dred Scott decision" affirming the right for all slave owners to take their slaves into the western territories freely because there was no such thing as a state where slavery was illegal, even though it was supposed to be. This means that it opened all of the territories to slavery. Therefore this decision overruled the policy of popular sovereignty that had to resolve this issue in the first place. Congress declared it unconstitutional.
