The U.S. Supreme Court case Dayton Coal and Iron Company, Limited v. Cincinnati, New Orleans and Texas Pacific Railway Company in 1915 revolved around a dispute over freight rates for the transportation of iron ore. The plaintiff, Dayton Coal and Iron Co., argued that the defendant railway company had violated Interstate Commerce Act by charging unreasonable rates on its iron ore shipments from mines to furnaces within Tennessee state lines. The court ruled in favor of the railway company stating that while it was true that interstate commerce laws did regulate railroads' charges for transporting goods across state lines, they did not apply when both origin and destination were within one state's borders even if part of journey crossed into another state before returning back - as long as no business was conducted outside original state boundaries during such detour.

In the dissenting opinion for Dayton Coal and Iron Company, Limited v. Cincinnati, New Orleans and Texas Pacific Railway Company, Justice Holmes disagreed with the majority's decision to uphold a lower court ruling that favored the railway company. He argued that there was insufficient evidence to support claims of unjust discrimination by the coal company against its customers in favor of those who used their own cars. The justice believed that it was not proven beyond reasonable doubt whether or not such an arrangement would result in substantial differences in transportation costs between different customers. Furthermore, he contended that even if such disparities did exist, they could be justified on grounds other than discriminatory intent - for instance due to variations in operating expenses associated with handling different types of freight cars. Therefore, according to him, without clear proof of intentional unfair treatment towards certain customers based solely on their use or non-use of private cars – which he maintained had not been provided – no violation of Interstate Commerce Act could be established.