In the case of Union Pacific Railway Company v. McDonald, 1893, the Supreme Court ruled in favor of Union Pacific Railway Company. The dispute arose when a land grant was given to the railway company by Congress for building a transcontinental railroad. However, before this grant was made official through patenting, John D. McDonald had already settled on part of that land and claimed it under preemption laws which allow settlers to claim unsettled lands by improving them and living there for a certain period of time. When he sued Union Pacific to keep his claim after they received their patent from Congress, both lower courts sided with him based on precedence set in previous cases involving similar circumstances (Railroad Co vs Deffeback). But upon reaching the Supreme Court level, it was decided that because patents are considered conclusive evidence of government grants and cannot be challenged at law once issued; therefore Mr.McDonald's preemptive rights were not applicable as they came into conflict with an existing federal statute granting said lands specifically to Union Pacific.

The dissenting opinion in the case of Union Pacific Railway Company v. McDonald argued that the majority's decision was inconsistent with previous rulings and failed to consider important aspects of contract law. The dissent, written by Justice Brewer, emphasized that a contract is not valid unless both parties have a clear understanding of its terms and conditions at the time it is made. In this case, McDonald had signed an agreement releasing Union Pacific from liability for any injuries he might suffer while working on their property without fully comprehending what he was signing due to his limited English proficiency. Therefore, according to Justice Brewer’s interpretation of contract law principles, such an agreement should be considered invalid as there wasn't mutual consent or meeting-of-the-minds between both parties involved in forming this contractual relationship. Furthermore, Justice Brewer criticized the majority's reliance on precedents which were not directly applicable to this particular situation involving language barriers and comprehension issues during contractual agreements.