In the Hammond v. Johnston case of 1891, the U.S Supreme Court was tasked with resolving a dispute over land ownership in California. The plaintiff, Hammond, claimed that he had purchased a piece of property from an individual who had obtained it through preemption rights under federal law. However, the defendant, Johnston argued that he held valid title to this same parcel of land due to his Mexican Land Grant claim which predates Hammond's purchase and is protected by the Treaty of Guadalupe Hidalgo between Mexico and United States (1848). The court ruled in favor of Johnston stating that when there are conflicting claims on a piece of property where one party has acquired it through preemption rights while another holds older grant recognized by treaty obligations; priority must be given to latter as per international law principles. This decision upheld respect for treaties and established precedence for future cases involving similar disputes.

The dissenting opinion in the Hammond v. Johnston case argued that the court majority had erred in its interpretation of the law and facts surrounding this land dispute. The dissent believed that there was no legal basis for overturning a lower court's decision, which had ruled in favor of Johnston based on established principles of property rights and possession. They contended that Hammond did not have valid claim to the disputed territory because he failed to properly register his ownership under California state laws governing mining claims. Furthermore, they pointed out inconsistencies between Hammond’s actions – such as leasing part of his alleged property to another party – with his assertion that he intended to possess and control all claimed lands exclusively for himself or his company. Therefore, according to them, it was unjustified for the Supreme Court majority ruling to disregard these key elements while deciding this case.