In M'Lemore v. Powell and Others, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving land in Mississippi that was owned by an Indian tribe. The plaintiff argued that the state court did not have jurisdiction because it violated federal law which stated that only Congress could regulate trade with Native American tribes. The defendants argued that the state court did have jurisdiction since they were citizens of Mississippi and thus subject to its laws. After considering both arguments, the Supreme Court ruled in favor of the defendants, finding that states do indeed possess authority over their own citizens regardless of any federal laws regarding Native Americans or other matters outside their borders. This ruling established precedent for future cases concerning similar issues between states and federally recognized entities such as Indian tribes or foreign countries.

In the case of M'Lemore v. Powell and Others, the Supreme Court was asked to decide whether a deed executed by an individual who had been declared insane should be considered valid. The majority opinion held that it should not, as such individuals are not legally capable of entering into contracts or other legal agreements. However, in his dissent Justice Story argued that there were no laws which explicitly prohibited such transactions from taking place and thus they should be allowed if all parties involved agreed to them willingly and without coercion. He further stated that any attempt to invalidate these types of deeds would lead to great injustice for those who relied on them in good faith, as well as creating confusion over what constituted a valid contract when dealing with mentally ill persons.