In 1846, a slave named Dred Scott sued in a Missouri court for his freedom. Scott argued that his service for Dr. Emerson in Illinois, a state wherein slavery was not allowed according to the terms of the Missouri Compromise, qualified him for his freedom. Eventually the case found its way all the way to the Supreme Court of the United States. The composition of the court reflected prevailing attitudes in the US at the time. As a result, the court ruled against Scott 7 to 2.
The most important aspect of this case was that blacks were considered property rather than people. Since they were property, they could no petition for rights. Chief Justice Taney wrote in his majority opinion that it was beyond dispute that the signers of the Declaration of Independence in 1776 had not intended to include blacks as citizens of the nation that they set out to establish.
As a result of this case, the division between the northern states and southern states widened. The economy of the southern states was built on slavery, and much of their social customs and standards revolved around it. The north was increasingly in the grip of abolitionist sentiments and anti-slavery movements. The Dred Scott vs. Sanford case only deepened the divide between north and south.
The decision was the apogee of the push to expand slavery. The US was expanding, and the Missouri Compromise resulted in diminishing political power in the north, due to the fact that many new states would be admitted as slave states. As a result, Democratic Party politicians sought to repeal the Missouri Compromise. Finally, in 1854, they succeeded by passing the Kansas-Nebraska act, which permitted states to decide for themselves south of the 40th parallel. With Dred Scott, the Taney court had de facto endorsed the unfettered expansion of slavery into the territories.