Retzer v. Wood, Collector was a United States Supreme Court case that dealt with the issue of whether a state could impose a tax on a federal officer. The case involved a dispute between the Collector of Internal Revenue for the District of Wisconsin, William Wood, and the plaintiff, John Retzer. Retzer was a federal officer who was appointed by the President of the United States to serve as a special agent of the Treasury Department. He was responsible for collecting taxes in Wisconsin. Wood attempted to impose a state tax on Retzer's salary, which Retzer refused to pay. Retzer argued that the state tax was unconstitutional because it interfered with the federal government's power to appoint and pay its own officers. The Supreme Court agreed with Retzer, ruling that the state tax was unconstitutional because it interfered with the federal government's power to appoint and pay its own officers. The Court held that the state tax was an unconstitutional burden on the federal government's power to appoint and pay its own officers. The Court also held that the state tax was an unconstitutional interference with the federal government's power to regulate its own officers. The Court's decision in Retzer v. Wood, Collector established that states cannot impose taxes on federal officers. This decision has been cited in numerous cases since then, and it remains an important precedent in the area of federalism.

In Retzer v. Wood, Collector, the Supreme Court was asked to decide whether a tax imposed by Congress on distilled spirits was unconstitutional because it violated the Fifth Amendment's prohibition against taking private property without just compensation. The majority opinion held that the tax did not violate this provision of the Constitution and thus could be enforced. However, Justice Field dissented from this decision and argued that while taxes are necessary for government operations, they must still adhere to constitutional limits in order to be valid. In his view, since no compensation had been offered for any losses incurred due to this particular tax on distilled spirits he believed it should have been declared unconstitutional as an infringement upon private property rights protected by the Fifth Amendment. He further noted that if such taxes were allowed then citizens would effectively become servants of their own governments with little protection against arbitrary taxation measures taken without consideration of individual circumstances or needs.