In the United States v. Green case of 1890, the Supreme Court ruled on a dispute involving land ownership in California. The defendant, Green, claimed that he had purchased a tract of land from an individual who held it under a Mexican grant recognized by the U.S government after California became part of the United States. However, this claim was disputed by another party who argued that they were entitled to possession due to their preemption rights under federal law which allowed settlers to stake claims on public lands before they were officially surveyed and sold by the government. The court found in favor of Green stating that once foreign grants are confirmed and patented by U.S authorities as per Treaty obligations (in this case referring to Treaty of Guadalupe Hidalgo), such lands cease being public lands subject for settlement or preemption under American laws. Therefore, any subsequent settler's claim is invalid against those holding title through such patents even if these patents are issued after someone else has settled thereon with intent to preempt when it was still considered 'public'. This decision reinforced respect for property rights established prior to annexation into US territory.

In the dissenting opinion for United States v. Green, 1890, it was argued that the majority's decision to uphold a conviction based on evidence obtained through an allegedly illegal search and seizure violated the Fourth Amendment rights of the defendant. The dissenting justices believed that any evidence acquired in such a manner should be considered "fruit of the poisonous tree" and therefore inadmissible in court. They contended that by allowing this kind of evidence to be used against defendants, it would set a dangerous precedent where law enforcement could potentially violate citizens' constitutional rights with impunity as long as they were able to secure convictions with illegally obtained evidence. This view held firm on upholding individual liberties over state power and maintaining strict adherence to constitutional principles.