In the United States v. Marshall Transport Co., 1943, the Supreme Court dealt with a dispute over transportation rates for hauling coal. The Interstate Commerce Commission (ICC) had approved higher rates proposed by railroads, but these were challenged by coal companies who argued that they were discriminatory and violated federal law. The District Court agreed with the coal companies and set aside ICC's order approving new rates. However, upon appeal to the Supreme Court, it was held that courts should not substitute their judgment for that of administrative agencies like ICC on complex economic issues unless there is no rational basis for agency’s decision or it violates statutory mandate. Therefore, since ICC had provided reasons why increased costs justified higher railroad freight charges and its decision did not violate any statute or constitutional provision, its rate approval was reinstated.

The dissenting opinion in the case of United States v. Marshall Transport Co., argued that the majority's interpretation of the Motor Carrier Act was too broad and not consistent with Congressional intent. The dissent believed that Congress did not intend for all employees involved in safety-related activities to be exempt from overtime pay, but only those directly responsible for safe operation on public highways. They contended that mechanics and other similar workers were not meant to be included in this exemption as they do not have direct responsibility over highway safety, even though their work indirectly contributes to it. Furthermore, they pointed out inconsistencies within the majority’s reasoning - while some employees whose work is critical for safety are excluded from overtime pay under their interpretation, others who perform similar tasks are entitled to it. This inconsistency further supported their belief that such a broad interpretation was incorrect.