In the case of United States et al. v. Chicago Heights Trucking Co. et al., 1939, the U.S Supreme Court was tasked with determining whether a tax imposed by Illinois on trucks carrying freight within its borders violated the Commerce Clause of the Constitution because it discriminated against interstate commerce. The trucking companies argued that they were being unfairly taxed for their participation in interstate trade while other businesses operating solely within state lines were not subject to such taxation. The court ruled in favor of Illinois, stating that there was no violation as long as taxes are applied equally to both intrastate and interstate commerce without any form of discrimination or preference towards one over another. It held that states have a right to impose fair and non-discriminatory taxes on commercial activities occurring within their jurisdiction even if those activities involve some aspect of interstate commerce. This ruling affirmed states' rights to levy taxes on business operations conducted within their boundaries provided these do not discriminate against or unduly burden out-of-state entities involved in similar operations.

The dissenting opinion in the case of UNITED STATES et al. v. CHICAGO HEIGHTS TRUCKING CO. et al., 1939, argued that the majority's decision was an overreach of federal authority and a misinterpretation of the Interstate Commerce Act (ICA). The dissenters believed that Congress did not intend for the ICA to regulate intrastate commerce or transactions involving only one state, as it would infringe upon states' rights to govern their own internal affairs. They also disagreed with the majority's interpretation of "transportation" under Section 1(3) and "common carrier by motor vehicle" under Section 203(a)(14), arguing these terms should be interpreted more narrowly to exclude activities such as loading, unloading, and temporary storage from regulation by interstate commerce laws unless they are directly related to transportation across state lines.