In the case of Jackson v. Emmons, 1899, the United States Supreme Court dealt with a dispute over land ownership in California. The plaintiff, Jackson, 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 Emmons argued that this was not possible as the original owner did not fulfill all necessary requirements to claim preemption rights and thus could not have legally sold it to Jackson. The court ruled in favor of Emmons stating that for someone to acquire land via preemption rights they must be either a U.S citizen or have declared their intention to become one; live on said land and make improvements upon it; and file a declaration with Land Office within appropriate time frame after settling thereon - none of which were fulfilled by original owner according to evidence presented at trial.

The dissenting opinion in Jackson v. Emmons argued that the majority's ruling was inconsistent with previous decisions of the Court and violated principles of equity. The dissent contended that a contract, once made, cannot be altered or changed without mutual consent from both parties involved. Therefore, it was unjust for one party to unilaterally change the terms of an agreement after its formation. Furthermore, they disagreed with the majority's interpretation of "reasonable time" within contracts law context as too vague and subjective; instead advocating for a more objective standard based on established legal precedents and norms. They also expressed concern about potential negative implications this decision could have on future contractual disputes by creating uncertainty around what constitutes a breach of contract.