The State of Missouri brought a case against the State of Iowa in front of the United States Supreme Court. The dispute was over land that had been granted to Missouri by Congress in 1820, and which Iowa claimed as part of its own territory. At issue was whether or not this land should be considered part of either state's boundaries. After reviewing both sides' arguments, the court ruled that while Congress had intended for this area to become part of Missouri when it passed legislation granting them ownership rights, they did not have authority to actually define state borders. Therefore, since neither side could prove title beyond reasonable doubt, no boundary line could be established between them and the disputed lands would remain unclaimed until further action from Congress is taken on the matter.

In the case of The State of Missouri v. The State of Iowa, Justice McLean delivered a dissenting opinion in which he argued that the Court should not have taken jurisdiction over this dispute between two states. He believed that it was inappropriate for the Supreme Court to intervene in matters concerning state boundaries and rights as these were issues best left to Congress or other political bodies. Furthermore, he noted that there was no clear legal precedent on how such disputes should be resolved and thus it would be difficult for the court to make an informed decision without further information from both parties involved. In conclusion, Justice McLean felt strongly that this case did not belong before the Supreme Court and instead should have been decided by another branch of government with more expertise in matters involving interstate relations.