In the United States v. Connor case of 1890, the Supreme Court ruled on a dispute involving land ownership in California. The plaintiff, the U.S government, claimed that defendant Thomas B. Connor illegally held possession of certain lands within railroad limits which were granted to Southern Pacific Railroad Company by an act of Congress in 1866 and later forfeited back to the U.S government due to non-compliance with construction timelines stipulated by said act. The defendant argued he had acquired these lands through preemption rights before they were initially granted to Southern Pacific Railroad Company and thus his claim was valid irrespective of subsequent forfeiture actions taken against this company. The court sided with Connor stating that once a settler has initiated a claim under preemption laws it becomes exclusive until abandoned or consummated into patent right; during this period no subsequent legislation can interfere with such claims unless explicitly stated so - which wasn't done when granting or forfeiting these lands from/to Southern Pacific Railroad Company.

In the dissenting opinion for United States v. Connor, it was argued that the majority's decision to uphold a conviction based on evidence obtained through an allegedly illegal search and seizure was incorrect. The dissenting justices believed that this ruling violated the Fourth Amendment rights of the defendant, which protect against unreasonable searches and seizures by law enforcement officials. They contended that any evidence obtained in such a manner should be deemed inadmissible in court due to its unlawful acquisition. Furthermore, they expressed concern over potential abuses of power by police officers if such actions were allowed to stand without consequence or reprimand from the courts. This disagreement highlighted differing interpretations of constitutional protections and their application within criminal justice proceedings.