United States v. Davis was a United States Supreme Court case that addressed the issue of whether a federal statute that imposed a tax on the income of individuals was constitutional. The Court held that the statute was constitutional, and that Congress had the power to impose such a tax. The case arose when the United States brought suit against William Davis, a resident of the District of Columbia, for failing to pay a federal income tax. Davis argued that the statute was unconstitutional, as it violated the Fifth Amendment's prohibition against the taking of private property for public use without just compensation. The Supreme Court rejected Davis' argument, holding that the statute was constitutional. The Court reasoned that the statute was a valid exercise of Congress' power to tax, and that the Fifth Amendment did not apply because the tax was imposed on individuals, not on property. The Court also noted that the tax was imposed on income, not on property, and that the tax was not a taking of property. The Court's decision in United States v. Davis established that Congress had the power to impose a federal income tax on individuals, and that such a tax did not violate the Fifth Amendment. The decision has been cited in numerous subsequent cases, and remains an important precedent in the area of taxation.

In United States v. Davis, the Supreme Court was asked to decide whether a federal law that imposed an additional tax on income derived from certain businesses violated the Constitution's Taxing and Spending Clause. The majority of justices held that Congress had acted within its constitutional authority in enacting this law, but Justice Field dissented. He argued that Congress did not have the power to impose such taxes because it would be tantamount to double taxation and could lead to oppressive taxation of individuals who were already subject to state taxes on their incomes. Furthermore, he argued that such a tax would interfere with states' rights by allowing Congress too much control over how they taxed their citizens' incomes. Ultimately, Justice Field concluded that while there may be some instances where it is appropriate for Congress to levy additional taxes beyond those imposed by states, this particular case was not one of them as it constituted an unconstitutional infringement upon state sovereignty and individual liberty.