The State Tonnage Tax Cases, Cox v. The Collector, was a case heard by the United States Supreme Court in 1871. The case centered around the question of whether or not the state of New York had the right to impose a tonnage tax on vessels entering its ports. The plaintiff, Cox, argued that the tax was unconstitutional because it violated the Commerce Clause of the United States Constitution. The Supreme Court ultimately ruled in favor of the plaintiff, finding that the tax was unconstitutional because it interfered with interstate commerce. The Court held that the tax was an unconstitutional burden on interstate commerce and that the state of New York did not have the authority to impose such a tax. The decision in this case established the precedent that states cannot impose taxes on interstate commerce. This decision has been cited in numerous cases since then, and it remains an important precedent in the area of interstate commerce.

In the State Tonnage Tax Cases, Cox v. The Collector (1871), Justice Field delivered a dissenting opinion in which he argued that Congress had no authority to impose tonnage taxes on vessels owned by citizens of one state and navigating between ports of another state. He believed that this was an unconstitutional exercise of power because it violated the Commerce Clause, which gives Congress exclusive control over interstate commerce. Furthermore, he argued that such taxation would be unfair as it would place an undue burden on those states whose vessels were subject to the tax while allowing other states to escape its effects entirely. In conclusion, Justice Field maintained that if Congress wished to regulate or tax interstate commerce then they must do so through legislation rather than executive action alone.