Dredd Scot still stands as one of the worst rulings ever made by the SCOTUS, And still today stands as a prime example of an activist court overreaching itself to further it's own agenda.
The Dissenting judges issued scathing and accurate dissent concerning the majority opinion. Detailing how the ruling flew in the face of established case law from state supreme courts and the Constitution itself. And last but not least how once the court declared Scott had not standing to bring the suit and it therefore had no jurisdiction, the court was obligated to simply dismiss the case and it was improper of the court to issue ANY rulings on the merits of the case after that.
The "fugitive slave act"
in which the word slave does not even appear. and whose wording was such that any state requiring the "slave" owner to prove that the "slave" was indeed his property "under the laws thereof" of their state prevented slave owners from taking escaped slaves back to their own states.
For the simple reason that no slave owner could establish that they owned the slave "Under the law thereof" of their states. since no state had legalized slavery and pro slavery leaders admitted public ally that not only did no slave holding states have laws legalizing slavery but such laws could not be passed under the US constitution or the constitutions of the states that all had Declaration of independence, and BOR style clauses written into their constitutions.
Senator James M. Mason (D., Va.) had publicly admitted in 1850, that there were no states that had legally established slavery. All states had slavery bans written into their constitutions via Declaration of Independence and Bill of Rights style clauses.
Even the abolitionists pointed out the illegality of slavery.
A number of abolitionists said, "When we say that slavery is illegal, we mean not merely that it is morally wrong, wicked, or sinful, in the sight of God, but that it is likewise unlawful, by the established principles of human jurisprudence, just as murder, arson, robbery, theft, and assault and battery, are unlawful, and that there is no more valid law for [favoring] the one than there is for the other. We mean that slaveholding is illegal, as other criminal practices are illegal. We affirm that there is no legislation in any of the States that makes it legal. . . . Slavery can not possibly be legalized. In its very nature it is incapable of legalization. The standard writers on common law affirm the impossibility of legalizing slavery, even by positive municipal law. They declare the right to liberty to be inalienable, and that statutes against fundamental morality are void. . . . The nature of civil government and of civil law, as defined by all standard writers on those subjects, proves it impossible to legalize slavery. 'To secure' man’s inalienable rights, 'governments are instituted among men.' And consequently they can have no lawful authority to violate the rights which they exist only to protect."
That was the driving force behind secession, the south's realization that their "peculiar institution" had no legal standing, even within their own states. This was why they were determined to secede and create their own constitution that legalized and protected slavery at the national level and forbid any of their member states to do away with it even in their own state.
It is also why the Confederates detested the Declaration of Independence.