In the case of Gibson v. United States in 1903, the U.S Supreme Court ruled on a dispute involving land ownership. The plaintiff, Gibson, claimed that he had purchased a piece of property from an individual who was part Native American and therefore not subject to certain federal laws regarding land sales. However, the defendant (the U.S government) argued that because this person was indeed considered Native American under law at the time of sale, they were unable to legally sell their allotted lands without approval from Congress - which hadn't been obtained in this instance. The court sided with the government's argument and held that despite any potential ambiguity about whether or not someone is classified as "Indian" under law for purposes such as these; it doesn't change their legal status nor does it affect how laws apply to them. Therefore since no congressional approval had been given for this particular sale between Gibson and his seller - regardless of whether they were deemed Indian or non-Indian - it was deemed invalid by default. This ruling reinforced both tribal sovereignty rights over reservation lands along with federal oversight responsibilities concerning transactions involving those properties.

In the dissenting opinion for Gibson v. United States, Justice Harlan argued that the majority's decision to uphold a law allowing military courts to try civilians during peacetime was unconstitutional and dangerous. He contended that this ruling violated the Fifth Amendment right of citizens not to be deprived of life, liberty or property without due process of law. Furthermore, he believed it undermined civilian control over the military by giving too much power to martial authorities even in times when civil courts were functioning properly. Justice Harlan warned against setting such a precedent as it could lead towards an erosion of individual rights and liberties under an increasingly powerful military establishment.