The U.S. Supreme Court case Ayrshire Collieries Corp. et al. v. United States et al., 1946, involved a dispute over the Interstate Commerce Commission's (ICC) authority to regulate private carriage by rail of commodities owned by the carrier itself or its affiliates for their own use and not for sale to others, known as "private carriage." The plaintiffs were coal companies who argued that such regulation exceeded the ICC's statutory powers under the Interstate Commerce Act and violated their constitutional rights under the Fifth Amendment due to deprivation of property without due process of law and denial of equal protection under laws. However, in a unanimous decision authored by Justice Harold Burton, it was held that Congress had intended for all forms of interstate transportation by rail carriers engaged in commerce among states be regulated uniformly regardless if they are public or private carriages; thus affirming ICC’s regulatory power over private carriages too. Furthermore, no violation against Fifth Amendment was found since there is no discrimination between different types/classes within same industry when applying regulations equally across board; hence providing equal protection under laws.

In the dissenting opinion for Ayrshire Collieries Corp. et al. v. United States et al., Justice Frankfurter argued that the Interstate Commerce Commission (ICC) should have been allowed to continue its regulation of railroad rates, as it had done since 1906 without any legal challenges until this case arose in 1946. He believed that Congress intended for the ICC to regulate these rates when they passed legislation creating the commission and giving it broad powers over interstate commerce, including railroads. Furthermore, he disagreed with his colleagues' interpretation of a recent amendment to federal law which they claimed removed coal from ICC's jurisdiction; instead, he interpreted this amendment as merely clarifying existing laws rather than changing them significantly enough to strip away ICC's authority over coal transportation prices.