In William Hunter v. The United States, the Supreme Court was asked to decide whether a contract between two parties could be enforced if it had been made in violation of an existing law. In this case, William Hunter had contracted with the United States government for supplies during the War of 1812 and failed to pay duties on certain imported goods as required by law. The lower court held that since he violated the law when making his contract, it could not be enforced against him and he was not liable for payment. However, upon appeal to the Supreme Court, Chief Justice Marshall reversed this decision and found that although Mr. Hunter's actions were illegal at the time of contracting they did not render his agreement void or unenforceable; instead he should still be held liable for payment under its terms despite having broken a statute in entering into it. This ruling established precedent which has been followed ever since: contracts are enforceable even if one party violates a preexisting legal obligation while forming them

In the case of William Hunter, Appellant vs. The United States, Appellees, the dissenting opinion was that Congress had no authority to pass a law which would allow for an appeal from a decision made by a court in one state to be heard in another state. This opinion argued that such an action would violate Article III of the Constitution and interfere with states' rights as outlined in the Tenth Amendment. Furthermore, it was argued that allowing appeals between different states could lead to confusion and inconsistency among courts across jurisdictions. Ultimately, this dissent concluded that Congress did not have any power or authority over matters concerning individual states’ judicial systems and should not be allowed to intervene on such matters without explicit permission from those respective states themselves.