Dred Scott was owned by Dr. Emerson of Missouri, an army surgeon. In his travels, Dr. Emerson had taken Mr. Scott with him to the free state of Illinois and locations in the territories. Dr. Emerson returned to his home state with Mr. Scott and his wife Harriett, along with their daughters Eliza (14) and Lizzie (7). Dr. Emerson then sold the whole family to John F. A. Sandford. Dred Scott sued for the freedom of himself and his family, claiming that they became free in Illinois and the territories. Mr. Scott and his family lost. The U.S. Supreme Court ruled that he was not a citizen and had no right to sue in U.S. courts.
The basic ruling of the United States Supreme Court, announced by Chief Justice Roger B. Taney, was that the framers of the Declaration of Independence were honorable men, therefore, when they held slaves while declaring universal human rights, they obviously could not have intended to include those of African descent, for that would have made them hypocrites rather than honorable men. Taney found it was "just and lawful" to reduce the black man to slavery "for his own benefit." Taney also pointed out that if blacks were citizens, they could do things protected by the Constitution, such as speak their mind, go as they please, and keep and carry arms wherever they went, which would produce "discontent and insubordination among them, and endangering the peace and safety of the State." This is what the Honorable Justice Taney had to say:
They had for more than a century before been regarded as beings of an inferior order, and altogether unfit to associate with the white race, either in social or political relations; and so far inferior, that they had no rights which the white man was bound to respect; and that the negro might justly and lawfully be reduced to slavery for his benefit. He was bought and sold, and treated as an ordinary article of merchandise and traffic, whenever a profit could be made by it. This opinion was at that time fixed and universal in the civilized portion of the white race. It was regarded as an axiom in morals as well as in politics, which no one thought of disputing, or supposed to be open to dispute; and men in every grade and position in society daily and habitually acted upon it in their private pursuits, as well as in matters of public concern, without doubting for a moment the correctness of this opinion...I guess now we know why the black race was "unhappy."
The language of the Declaration of Independence is equally conclusive:
It begins by declaring that, 'when in the course of human events it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth the separate and equal station to which the laws of nature and nature's God entitle them, a decent respect for the opinions of mankind requires that they should declare the causes which impel them to the separation.'
It then proceeds to say: 'We hold these truths to be self-evident: that all men are created equal; that they are endowed by their Creator with certain unalienable rights; that among them is life, liberty, and the pursuit of happiness; that to secure these rights, Governments are instituted, deriving their just powers from the consent of the governed.'
The general words above quoted would seem to embrace the whole human family, and if they were used in a similar instrument at this day would be so understood. But it is too clear for dispute, that the enslaved African race were not intended to be included, and formed no part of the people who framed and adopted this declaration; for if the language, as understood in that day, would embrace them, the conduct of the distinguished men who framed the Declaration of Independence would have been utterly and flagrantly inconsistent with the principles they asserted; and instead of the sympathy of mankind, to which they so confidently appealed, they would have deserved and received universal rebuke and reprobation.
Yet the men who framed this declaration were great men-high in literary acquirements-high in their sense of honor, and incapable of asserting principles inconsistent with those on which they were acting. They perfectly understood the meaning of the language they used, and how it would be understood by others; and they knew that it would not in any part of the civilized world be supposed to embrace the negro race, which, by common consent, had been excluded from civilized Governments and the family of nations, and doomed to slavery. They spoke and acted according to the then established doctrines and principles, and in the ordinary language of the day, and no one misunderstood them. The unhappy black race were separated from the white by indelible marks, and laws long before established, and were never thought of or spoken of except as property, and when the claims of the owner or the profit of the trader were supposed to need protection...
The legislation of the States therefore shows, in a manner not to be mistaken, the inferior and subject condition of that race at the time the Constitution was adopted, and long afterwards, throughout the thirteen States by which that instrument was framed; and it is hardly consistent with the respect due to these States, to suppose that they regarded at that time, as fellow-citizens and members of the sovereignty, a class of beings whom they had thus stigmatized; whom, as we are bound, out of respect to the State sovereignties, to assume they had deemed it just and necessary thus to stigmatize, and upon whom they had impressed such deep and enduring marks of inferiority and degradation; or, that when they met in convention to form the Constitution, they looked upon them as a portion of their constituents, or designed to include them in the provisions so carefully inserted for the security and protection of the liberties and rights of their citizens. It cannot be supposed that they intended to secure to them rights, and privileges, and rank, in the new political body throughout the Union, which every one of them denied within the limits of its own dominion. More especially, it cannot be believed that the large slaveholding States regarded them as included in the word citizens, or would have consented to a Constitution which might compel them to receive them in that character from another State. For if they were so received, and entitled to the privileges and immunities of citizens, it would exempt them from the operation of the special laws and from the police regulations which they considered to be necessary for their own safety. It would give to persons of the negro race, who were recognised as citizens in any one State of the Union, the right to enter every other State whenever they pleased, singly or in companies, without pass or passport, and without obstruction, to sojourn there as long as they pleased, to go where they pleased at every hour of the day or night without molestation, unless they committed some violation of law for which a white man would be punished; and it would give them the full liberty of speech in public and in private upon all subjects upon which its own citizens might speak; to hold public meetings upon political affairs, and to keep and carry arms wherever they went. And all of this would be done in the face of the subject race of the same color, both free and slaves, and inevitably producing discontent and insubordination among them, and endangering the peace and safety of the State.
It is impossible, it would seem, to believe that the great men of the slaveholding States, who took so large a share in framing the Constitution of the United States, and exercised so much influence in procuring its adoption, could have been so forgetful or regardless of their own safety and the safety of those who trusted and confided in them.
For a happier result, see the ruling in The Amistad, 40 U.S. 518 (1841), the subject of a recent movie. Because the blacks were kidnapped from Africa recently, the court system allowed them the rights of freedom and self-defense barred from other African-Americans. You can find this ruling at FindLaw, http://laws.findlaw.com/US/40/518.html.