The U.S. Supreme Court case Maurer et al., Trading as Maurer & Myers Auto Convoy, v. Hamilton, Secretary of Revenue of Pennsylvania, et al., 1939 revolved around the constitutionality of a Pennsylvania statute that imposed an annual license fee on motor vehicles engaged in intrastate commerce but exempted those involved in interstate commerce. The plaintiffs were operators who transported cars from manufacturers to dealers within the state and argued that this law violated the Commerce Clause by discriminating against intrastate business. However, the court ruled against them stating that states have power to tax businesses operating exclusively within their borders even if similar interstate businesses are immune under federal law due to Interstate Commerce Commission regulations or other reasons related with promoting free trade among states.

In the dissenting opinion for Maurer et al., Trading as Maurer & Myers Auto Convoy, v. Hamilton, Secretary of Revenue of Pennsylvania, et al., Justice McReynolds argued that the majority's decision was inconsistent with previous rulings concerning interstate commerce. He contended that Pennsylvania’s tax on trucks used in interstate transport violated the Commerce Clause by placing an undue burden on such activities. According to him, this case should have been decided based on precedent set in cases like Helson and Randolph v. Kentucky (279 U.S 245) where it was held that a state cannot impose taxes upon vehicles engaged exclusively in interstate commerce beyond its fair share for road use and maintenance costs proportionate to intrastate traffic. By allowing Pennsylvania to levy a flat fee regardless of how much or little each truck uses its roads compared to local traffic, he believed the Court had effectively sanctioned discriminatory taxation against out-of-state businesses which is contrary to principles underlying our federal system.