In Gilman v. Philadelphia, the Supreme Court of the United States heard a case involving an ordinance passed by the city of Philadelphia that required all persons engaged in business within its limits to pay a license fee for each employee they hired. The plaintiff, William Gilman, argued that this ordinance was unconstitutional because it violated his right to due process under the Fourteenth Amendment and interfered with Congress’s power over interstate commerce. In its decision, the court held that while states have broad powers to regulate their own internal affairs, they cannot pass laws which interfere with or impede Congress's exclusive authority over interstate commerce. Furthermore, any law which violates due process rights is invalid as well; therefore since Philadelphia’s ordinance did both these things it was declared unconstitutional and void.

In the case of Gilman v. Philadelphia, Justice Field delivered a dissenting opinion that argued against the majority's decision to uphold an ordinance passed by the City of Philadelphia which imposed a tax on all persons engaged in business within its limits. He asserted that this was an unconstitutional exercise of power because it violated both state and federal laws. Furthermore, he argued that such taxation could not be justified as necessary for public purposes since there were other means available to raise revenue without infringing upon individual rights or privileges granted under either state or federal law. Finally, he concluded by stating his belief that if allowed to stand, this ordinance would set a dangerous precedent whereby any municipality could impose taxes on individuals with impunity and without regard for their constitutional rights.