The U.S. Supreme Court case Oregon Short Line and Utah Northern Railway Company v. Conlin in 1895 revolved around a dispute over land rights between the railway company and an individual named Conlin. The railway company claimed that it had been granted certain lands by Congress under the Pacific Railroad Acts, which were intended to encourage westward expansion through railroad construction. However, Conlin argued that he had acquired valid title to some of this land before the grant was made to the railroad company, thus making him its rightful owner. The court ruled in favor of Conlin, stating that his claim on the disputed property predated any potential claims by the railway company as per their Congressional grants. The ruling emphasized that such grants from Congress did not have retroactive effect; they could only apply prospectively from their date of issuance onwards - meaning they couldn't affect or override prior existing legal rights or claims on properties involved.

In the dissenting opinion for Oregon Short Line and Utah Northern Railway Company v. Conlin, it was argued that the majority's decision to uphold a tax imposed by Montana on railroads operating in multiple states violated principles of interstate commerce. The dissent contended that because the railroad company operated across state lines, its operations were part of interstate commerce and thus should be exempt from state taxation under federal law. They believed this interpretation was consistent with previous Supreme Court rulings which had held that states could not interfere with or burden interstate commerce through taxation or regulation. Furthermore, they disagreed with the majority's view that only Congress could determine whether such taxes constituted an interference with interstate trade; instead, they asserted it was within the purview of courts to make such determinations based on established legal precedents and principles.