In the case of Camou v. United States in 1897, the U.S Supreme Court ruled on a dispute regarding property rights in California that dated back to Mexican rule before the territory became part of America. The plaintiff, Camou, claimed ownership based on an old Spanish land grant and argued that his claim was validated by a patent issued by the United States government under provisions of the Treaty of Guadalupe Hidalgo (which ended Mexican-American War). However, there were conflicting claims from other parties who had purchased or acquired parts of this same land after it had been declared public domain due to non-confirmation by Congress within two years as required by law at that time. The court held that even though Camou's title may have been confirmed later through issuance of a patent certificate, it did not retroactively validate his earlier claims against those who obtained their titles when the land was considered public domain. Therefore, these subsequent owners' rights were upheld over Camou’s claim.

In the dissenting opinion for Camou v. United States, it was argued that the court erred in its decision to uphold a lower court's ruling which allowed evidence obtained through an illegal search and seizure to be used against the defendant. The dissenting justices believed this violated the Fourth Amendment rights of citizens, which protect them from unreasonable searches and seizures. They contended that any evidence obtained illegally should not be admissible in court as it undermines constitutional protections and sets a dangerous precedent for future cases. Furthermore, they expressed concern over potential abuses of power by law enforcement officials if such practices were permitted without consequence or oversight.