In a 7-2 opinion, a majority of the Supreme Court ruled in favor of Sanford.* Chief Justice Taney wrote the opinion for the Court.  The Court first decided that African Americans were not citizens as defined by the Constitution.  They then considered the merits of the case, ruling that slaves did not become free simply by entering a free state or a territory that had not yet become a state.  This overturned the ruling of the lower federal court, but affirmed the ruling of the Missouri Supreme Court.

The Supreme Court first concluded that African Americans were not citizens as defined by the Constitution, and therefore, the Supreme Court and lower federal courts had no jurisdiction to hear this case.  The decision cited Article III, Section 2 of the Constitution which gives federal courts the power to hear cases “between Citizens of different States.”  To determine the definition of “citizens,” the justices considered the intent of the framers of the Constitution.  They noted that at the time the Constitution was written, people of African descent, both slave and free, were “regarded as beings of an inferior order” and were “so far inferior that they had no rights which the white man was bound to respect.”  Believing that the Court should not “give to the words of the Constitution a more liberal construction …than they were intended to bear when the instrument was framed and adopted,” the Court concluded that people of African descent were not citizens, and could therefore “claim none of the rights and privileges which that instrument provides for and secures to citizens of the United States.”  This included the ability to bring suit in federal court.

Even though the Court determined that it did not have jurisdiction to hear this case because it did not involve “Citizens of different States,” the justices ruled on the merits of case anyway.  They first argued that the power of Congress to regulate the internal workings of the territories that had not yet become states was limited.  They concluded that an act of Congress prohibiting citizens from “owning [slaves] in the territor[ies] … is not warranted by the Constitution, and is therefore void.”  The Court thereby struck down the Missouri Compromise as unconstitutional because Congress did not have the power under the Constitution to determine whether slavery was allowed in the territories, even those these were not states.    

In addition, the Court concluded that slaves could not be made free simply by entering a free state or territory.  This would deprive slave owners of their property without giving them due process of law as required by the Fifth Amendment.  Accordingly, “an act of Congress which deprives a citizen of the United States of his …property, merely because he … brought his property into a particular Territory of the United States” was unconstitutional.  The Court held, therefore, that Dred Scott and his family were “property” and were not made free simply by virtue of the fact that they were brought into a free territory.

*The defendant in this case was John Sanford, but the Court record misspelled his name, and the Court continues to call the case Dred Scott v. Sandford.