Dunlop v. Hepburn, et al. was a United States Supreme Court case that dealt with the issue of whether or not Congress had the power to regulate commerce between states. The plaintiff argued that Congress did have this power and cited Article I, Section 8 of the Constitution as evidence for their argument. The defendants countered by arguing that only state legislatures could pass laws regulating interstate commerce and thus Congress lacked such authority. In a unanimous decision, Chief Justice John Marshall wrote an opinion in favor of the plaintiff which established Congressional authority over interstate commerce under Article I, Section 8 of the Constitution. This landmark ruling set forth important precedent regarding federalism and has been used to support numerous other cases involving congressional powers since then

In the case of Dunlop v. Hepburn, et al., Chief Justice John Marshall delivered a dissenting opinion on behalf of himself and two other justices. He argued that Congress had no authority to pass laws regulating commerce between states because it was not enumerated in the Constitution as one of their powers. Furthermore, he believed that such power should be left to the individual states since they were closer to local interests than Congress was. He also argued that if this law were allowed to stand, then it would open up a “wide field for legislative interference” with state sovereignty and could lead down an unconstitutional path where federal legislation overrides state laws without any constitutional basis or justification. Ultimately, Marshall concluded by stating his belief that this law violated both the spirit and letter of the Constitution and should therefore be declared void by the Court.