In Brushaber v. Union Pacific Railroad Co., the Supreme Court of the United States declares the federal income tax constitutional.

Brushaber v. Union Pacific Railroad Co., 240 U.S. 1 (1916), was a landmark United States Supreme Court case in which the Court upheld the validity of a tax statute called the Revenue Act of 1913, also known as the Tariff Act, Ch. 16, 38 Stat. 166, enacted pursuant to Article I, section 8, clause 1 of, and the Sixteenth Amendment to, the United States Constitution, which did not confer any new powers of taxation. The case clarified that federal income tax is an excise (privilege) tax. "The income [commonly-defined] is not the subject of the tax; it is the basis for determining the amount of tax."