Simply speaking, the Dred Scott Decision eliminated any hope of reviving the Missouri Compromise of 1820. In 1854, the Kansas-Nebraska Act had essentially nullified the Missouri Compromise. This act allowed each territory to decide whether or not slavery would be permitted, regardless of whether it was north of the 36°30 parallel. This made the Missouri Compromise, which had established that previous delineation between slave and free territory irrelevant.

With the Dred Scott case, the southern justices on the Supreme Court, writing for the majority, put the final nail in the coffin of the Missouri Compromise. Scott had sued for his freedom based on the argument of being brought to a free state. By siding against Scott, the Court effectively said that slavery could be permitted anywhere, regardless of previous agreements and decisions and that Congress had no authority to decide to where slavery could exist or not.

The Missouri Compromise was made in 1820. When Missouri wanted to enter the country as a slave state, it would have created an unequal number of free and slave states. Thus, this compromise allowed Missouri to enter as a slave state while Maine would enter as a free state. To deal with the expected expansion of the United States, the Missouri Compromise established the 36°30’ line. No slavery would be allowed in any part of the Louisiana Territory that was North of this line.

When Dred Scott's owner took him to a free territory, lawyers representing Dred Scott went to court and argued he should be freed because he was taken to a free territory. The Supreme Court ruled Dred Scott would not be freed. It also said Dred Scott had no right to sue because he wasn’t a citizen. Further, the ruling stated the Missouri Compromise was unconstitutional because Congress didn’t have the authority to ban slavery. Since slaves were viewed as property, Congress couldn’t ban slavery in the territories.