In the case of Michigan Public Utilities Commission et al. v. Duke, Doing Business as Duke Cartage Company (1924), the U.S Supreme Court ruled in favor of state regulatory power over intrastate commerce. The dispute arose when a trucking company owned by Mr. Duke was transporting goods within Michigan's borders and was subjected to regulations imposed by the Michigan Public Utilities Commission (MPUC). These included licensing requirements and rate controls which Mr. Duke argued were unconstitutional under both federal law governing interstate commerce and his Fourteenth Amendment rights to due process and equal protection under law. The court held that since Mr.Duke’s operations were entirely within one state, they constituted intrastate rather than interstate commerce, thus falling outside federal jurisdiction but well within MPUC's authority to regulate for public safety purposes.The court also found no violation of 14th amendment rights as it deemed these regulations reasonable exercises of police powers aimed at ensuring road safety & fair rates for consumers.

In the dissenting opinion for Michigan Public Utilities Commission et al. v. Duke, the justice argued that state regulation of intrastate commerce should not be invalidated by federal law unless there is a direct conflict between them. The justice believed that while Congress has the power to regulate interstate commerce, it does not have absolute authority over all aspects of transportation within individual states. He emphasized that each state has its own unique conditions and requirements which may necessitate different regulations from those imposed at a national level by Congress. Therefore, he disagreed with the majority's decision to strike down Michigan's regulatory scheme on grounds of preemption by federal law, arguing instead for a more nuanced approach in determining whether or not such conflicts exist.