In the United States v. Western Union Telegraph Company and Union Pacific Railway Company case of 1895, the Supreme Court was tasked with determining whether a contract between Western Union and Union Pacific violated antitrust laws. The two companies had agreed that Western Union would have exclusive rights to operate telegraph lines along the railway's routes for fifty years. The government argued this agreement constituted an illegal monopoly under the Sherman Antitrust Act of 1890. The court ruled in favor of both companies, stating that while they did indeed hold a monopoly over telegraph services on those specific rail routes, it wasn't unlawful because there were other viable options available for sending messages across long distances (such as mail or telephone). Furthermore, since their agreement didn't prevent competition from building parallel lines alongside existing ones if desired, it couldn't be considered restrictive trade practice. This decision set an important precedent by clarifying what constitutes monopolistic behavior under U.S law and how such cases should be evaluated - not just based on market dominance but also considering potential barriers to entry for competitors.

In the dissenting opinion for United States v. Western Union Telegraph Company and Union Pacific Railway Company, the justice argued that the majority's decision was a misinterpretation of both law and fact. The justice disagreed with the majority's view that Western Union had exclusive rights to operate telegraph lines along railway routes under an 1862 Act of Congress. Instead, he believed this right was not absolute but subject to reasonable regulation by state authorities in order to protect public interests. He also contended that there were no grounds for concluding that Western Union’s agreement with Union Pacific constituted a monopoly or restraint of trade as prohibited by Sherman Antitrust Act because it did not prevent other companies from constructing their own telegraph lines along railroad routes if they secured permission from relevant railroads. Furthermore, he pointed out factual errors made by lower courts which led them to incorrect conclusions about certain aspects of case evidence.