In the case of Smith v. Cahoon, Sheriff in 1930, the U.S Supreme Court ruled on a dispute regarding Florida's Motor Vehicle Act. The act required all commercial motor vehicles to obtain a license from the state before operating within its borders and was challenged by an interstate trucking company as being discriminatory against out-of-state businesses and thus violating both commerce clause and equal protection clause of the Constitution. However, the court upheld Florida's law stating that it did not discriminate against interstate commerce because it applied equally to all operators whether they were based in or outside of Florida. Furthermore, it held that states have broad power under their police powers to regulate highways for safety purposes which includes requiring licenses for commercial vehicles using them.

In the dissenting opinion for Smith v. Cahoon, it was argued that Florida's law requiring a permit to operate a motor vehicle on public highways did not infringe upon any constitutional rights. The dissent emphasized that driving is not an inherent right but rather a privilege granted by the state, subject to reasonable regulation in order to ensure public safety and welfare. It further contended that since vehicles are potentially dangerous machines capable of causing great harm when improperly handled, states have every right to require proof of competency before granting permission for their operation on public roads. Therefore, according to this view, Florida’s requirement of obtaining permits does not violate due process or equal protection clauses as claimed by the appellant.