In the case of William Campbell and Thirty-Seven Others v. Clement Boyreau, the Supreme Court was asked to decide whether a contract between two parties could be enforced if it had been made in violation of state law. The plaintiffs argued that they had entered into an agreement with Boyreau for him to transport them from New Orleans to Texas, but he failed to fulfill his obligations under the contract. They sought damages for breach of contract and argued that even though their agreement violated Louisiana's Passenger Act, which prohibited such contracts without prior approval from local authorities, they should still be able to enforce it against Boyreau since he was aware of its illegality when entering into it. The Supreme Court disagreed with this argument and held that any contracts made in violation of state laws are voidable at either party’s discretion; thus, no action can be taken against one who fails or refuses to perform such a contract as there is no valid obligation on either side.

Justice McLean delivered the dissenting opinion in this case. He argued that the majority's decision was contrary to established precedent and would lead to a dangerous expansion of federal power. The issue at hand was whether or not Congress had authority under the Constitution to pass legislation granting land titles for certain individuals who had settled on public lands prior to its passage. Justice McLean maintained that such an act exceeded Congress' enumerated powers, as it interfered with state sovereignty over property rights and constituted an unconstitutional taking of private property without just compensation. Furthermore, he argued that if such acts were allowed, then any individual could claim title by simply settling on public lands before they are granted away by Congress - thus leading to chaos and confusion regarding ownership rights across states. In conclusion, Justice McLean believed that allowing this type of congressional action would be detrimental both constitutionally and practically speaking; therefore he dissented from the majority opinion which upheld it as constitutional law.