The License Tax Cases (United States v. Vassar) was a Supreme Court case that addressed the issue of whether the federal government had the power to impose a tax on businesses. The case was brought by the United States against Vassar, a merchant in New York, who had refused to pay a federal license tax. The Court held that the federal government did have the power to impose a tax on businesses, but that the tax must be uniform throughout the United States. The Court also held that the tax must be reasonable and not oppressive. The decision was a major victory for the federal government, as it established the power of the federal government to impose taxes on businesses. The decision also established the principle of uniformity in taxation, which is still in effect today.

In the License Tax Cases (United States v. Vassar), the Supreme Court was asked to decide whether Congress had the power to impose a tax on certain businesses in order to raise revenue for government operations. The majority opinion held that Congress did have such authority, but Justice Swayne dissented from this ruling and argued that it violated both the letter and spirit of Article I, Section 8 of the Constitution which grants Congress only limited powers over taxation. He further argued that if this decision were allowed to stand, then there would be no limit on what taxes could be imposed by Congress as long as they are labeled "license taxes". As such, he concluded that any attempt by Congress to levy a license tax beyond its enumerated powers should not be upheld by courts.