Board of Commissioners v. Gorman was a United States Supreme Court case that addressed the issue of whether a state could impose a tax on the sale of goods within its borders. The case involved a dispute between the Board of Commissioners of the City of St. Louis and the Gorman family, who owned a store in the city. The Board had imposed a tax on the sale of goods within the city, and the Gormans argued that the tax was unconstitutional. The Supreme Court held that the tax was constitutional, finding that the power to tax was an inherent power of the state and that the tax was not an unconstitutional burden on interstate commerce. The Court noted that the tax was not discriminatory and that it was applied equally to all goods sold within the city. The Court also noted that the tax was not excessive and that it was necessary to raise revenue for the city. The Court's decision in Board of Commissioners v. Gorman established that states have the power to impose taxes on goods sold within their borders, provided that the taxes are not discriminatory and are not excessive. The decision also established that such taxes do not violate the Commerce Clause of the United States Constitution.

Justice Field delivered the dissenting opinion in Board of Commissioners v. Gorman, arguing that the majority's decision was contrary to established precedent and should be overturned. He argued that a state legislature cannot pass laws which impair or destroy vested rights acquired under existing contracts, citing numerous cases from other states as well as decisions by this Court itself. Furthermore, he noted that while it is true that a state can modify its own laws so long as it does not interfere with vested rights, such modifications must be reasonable and justifiable; otherwise they are unconstitutional. In this case, Justice Field argued there was no justification for the law passed by Kansas' legislature since it did not serve any public purpose but instead only served to benefit private interests at the expense of those who had already acquired property rights through contract. Therefore, he concluded that the law should have been declared invalid on constitutional grounds and urged his colleagues to reverse their ruling accordingly.