The case you are referring to is Dred Scot v. Sandford . The Chief Justice was Roger B. Taney and the Associate Justices were Samuel Nelson, Benjamin R. Curtis, Robert C. Grier, Peter V. Daniel, James M. Wayne, John McLean, John Catron, and John Campbell.
The elements of this case were that, Dred Scott, was a ***** Slave, formerly the property of Dr. Emerson, a surgeon in the United States Army. In 1834, Emerson took Scott to the free State of Illinois, and then in 1836 to Fort Snelling which was in the Wisconsin Territory, free soil under the Missouri Compromise. (Note: Territories are under federal rule and not part of States.) Eventually Emerson returned to Missouri taking Scott with him. The surgeon died shortly thereafter, and title to Scott eventually passed to John A. Sandford, a citizen of New York.
In 1846 Scott brought suit in the Missouri State courts for his freedom. At the time this action apparently had no political import. Though Scot won a favorable decision in the lower courts, the Missouri Supreme Court eventually rejected his plea on the grounds that the laws of Illinois and of free territory did not have extraterritorial status in Missouri and could not affect his status as a slave after his return.
Scott’s attorney then began, in 1854, a new suit against Sandford in the United States Circuit Court for Missouri. The case was now frankly political in character, and both sides pressed it through to a conclusion in order to obtain a judicial opinion upon slavery in the territories.
Scott’s right to sue Sandford in a federal court rested upon his contention that he was a citizen of the State of Missouri, and that the case involved a suit between citizens of different states. (Note: if accepted as factual, such suits fall under federal jurisdiction). Sandford replied to Scott’s suit with a plea in abatement, that is, a demand that the court dismiss the case for want of jurisdiction, on the ground that since Scott was a ***** he was not a citizen of Missouri. To this plea, Scott demurred. (Meaning that he believed that he did not have to reply to this plea of abatement.) The circuit court sustained the demurrer (thereby implying that Scott might be a citizen), but it then returned a verdict in favor of Sandford. Scott now appealed to the Supreme Court of the United States on a writ of error. (Meaning that he believed the circuit court made an error with that opinion.
When first hearing the case most jurors (of the Supreme Court) were of a mind to dismiss the case for want of jurisdiction based on a case precedent of Strader v. Graham . In this case the court without dissent had refused to consider the argument that a slave automatically became free through residence in a free State. Although the majority justices were preparing an opinion to dismiss the Dred Scott case when the two antislavery justices announced that they were preparing dissenting opinions discussing the status of slaves in territories which had not been addressed in Strader v. Graham.
It should be kept in mind that dismissing this case may have occurred anyway except for the political pressure brought to bear on the justices from the furor raging in Kansas as the arguments were occurring during the year of 1856. The pressure was on to have a clear opinion of the matter, so the case was reviewed.
Finally on 6 March 1857 the court delivered its opinion with a seven to two split. All nine justices wrote separate opinions and in no two of them was the reasoning precisely alike. However, Chief Justice Taney’s decision became the one most discussed and debated. In Taney’s opinion, Scott could not sue because he was not a citizen of the United States. There were two reasons why Scott was not a citizen: first because he was a *****, and second, because he was a slave. Taney supported his claim that no *****, not even a freeman, could be a citizen, by citing the *****’s long-established servile position, the slave codes, and other evidence proving that as of 187 (the date of the ratification of the Constitution) the States had excluded Negroes from citizenship. Hence, Negroes were not citizens of the United States within the meaning of the Constitution. In part he opined, “ . . . It becomes necessary . . . to determine who were citizens of the several States when the Constitution was adopted. In the opinion of this court, the legislation and histories of the times, and the language used in the Declaration of Independence, show, that neither the class of persons who had been imported as slaves, nor their descendants, whether they become free or not, were then acknowledged as part of the people, nor intended to be included in the general words in that memorable instrument. . . . they had for more than a quarter of 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.”
The weakness of this argument was in the theory on which this argument was based: That is, since the establishment of independence certain Northern States had extended political rights to free Negroes. If a State could properly confer citizenship, as the Constitution implied (keep in mind that the definition of citizenship was not fully defined legally until the adoption of the Fourteenth Amendment in 1868), then a ***** might thus conceivably be a citizen of a State and entitled to sue in the federal court.
Taney avoided this difficulty by drawing a distinction between State citizenship and the national citizenship; that is, by evoking the doctrine of duel citizenship.
The preceding should provide you with enough ammunition to present your case as Taney clearly did. However, let make a word of caution and that is, not to view this case through glasses colored with the views of our times. You mentioned the word morals in your question, such has no place in law and certainly had no place in this case. If your opponents bring forth such an argument, request it to be excluded as not part of the case. Taney was correct and his decision remained so as a matter of law until the Thirteenth and Fourteenth Amendments (1865 and 1868 respectfully) and the justification of the adoption of the Fourteenth Amendment in the case of Texas v. White . Your argument in support of Taney’s decision is on firm solid Constitutional ground.
It was the rare case which did not address items other than what the decision was based. Such offerings were no more than an indicator of attitudes of the court members making the opinions and they had no bearing on the legal standing of the case. However, this case did have some secondary statements addressing property. This was incorporated in Taney’s second judgment by opining that Scott could not be freed just because he was a temporary resident of federal territory and that there existed the Missouri Compromise’s prohibition of slavery and that such an attempt top free him on those grounds would be unconstitutional. That is, the property right of a slave holder to his slaves merited full protection under the Constitution, particularly the protection of the Fifth Amendment’s due process clause.
Most of these statements (preceding) are derived from my personal library and past studies in these areas, but the best direct source is the text of the cases Dred Scott v. Sandford ; and Strader v. Graham ; and the Constitution.