This independence was fortified by an early Supreme Court decision described later by the Warren Court in this way:

In 1803, Chief Justice Marshall, speaking for an unanimous Court, referring to the Constitution as "the fundamental and paramount law of the nation," declared in the notable case of Marbury v. Madison... that "It is emphatically the province and duty of the judicial department to say what the law is." This decision declared the basic principle that the federal judiciary is supreme in the exposition of the law of the Constitution, and that principle was (sic) ever since been respected by this Court and the Country as a permanent and indispensable feature of our constitutional system....

In 1853, Dred Scott sued one Sandford for damages in Missouri for unlawfully holding him and his family as slaves. Sandford claimed they were his property, and Scott could not be a citizen able to maintain the action because he had been at all times a slave. The question was whether Scott had become free pursuant to a Missouri court judgment to that effect by reason of having previously been taken into free territory in which Congress had prohibited slavery. Chief Justice Taney's constitutional interpretation was that the Act of Congress relied upon by Scott was void; that his status was continuously that of a slave unable to maintain an action; and that he and his family were the property of Sandford. The opposition, by Justice Curtis in dissent and others, to such a judicial curtailment of the power of Congress over the treatment of such persons in areas under its jurisdiction necessarily focused attention on the majority's rationale — the slaves' lack of rights under the Constitution.