Direct Tax
The Constitution distinguishes between “direct” taxes, which must be apportioned among the states by population (Art. I §2, cl. 3; Art. I §9, cl. 4), and other taxes (“duties, imposts, and excises”), which must be uniform throughout the United States (Art. I §8, cl. 1). The line between the two categories has been the subject of two centuries of doctrinal work and remains imperfectly drawn.
The early understanding, derived from Hylton v. United States (1796), was narrow: only capitation taxes and taxes on real property were “direct.” Under this view, most federal taxes — including income taxes — fell into the broad “indirect” category and required only uniformity.
Pollock v. Farmers’ Loan & Trust Co. (1895) disrupted this understanding by holding that taxes on income from property (rents, interest, dividends) were themselves taxes on the property and therefore direct. Pollock effectively struck down the income tax of 1894 and triggered the constitutional crisis that the Sixteenth Amendment resolved.
The Sixteenth Amendment removed apportionment as a barrier to “taxes on incomes, from whatever source derived” — it did not redefine “direct tax” generally. So Pollock’s underlying analysis of what counts as a direct tax remains technically alive. This is why proposals for a federal wealth tax raise serious constitutional questions that did not have to be answered to enact the income tax: a wealth tax sits squarely in the Pollock framework that the Sixteenth Amendment routed around but did not dismantle.