Annotated Sixteenth
Amendment
South Carolina v. Baker, 485 U.S. 505, 523 n.13 (1988)
“The legislative history merely shows that the words "from whatever source derived" of the Sixteenth Amendment were not affirmatively intended to authorize Congress to tax state bond interest or to have any other effect on which incomes were subject to federal taxation, and that the sole purpose of the Sixteenth Amendment was to remove the apportionment requirement for whichever incomes were otherwise taxable. 45 Cong. Rec. 2245-2246 (1910); id., at 2539; see also Brushaber v. Union Pacific R. Co., 240 U.S. 1, 17-18 (1916). ”
Wright v. U.S., 302 U.S. 583 (1938)
'From whatever source derived,' as it is written in the Sixteenth Amendment, does not mean from whatever source derived. Evans v. Gore, 253 U.S. 245 , 40 S.Ct. 550, 11 A.L.R. 519. See, also, Robertson v. Baldwin, 165 U.S. 275, 281 , 282 S., 17 S.Ct. 326; Gompers v. United States, 233 U.S. 604, 610 , 34 S.Ct. 693, Ann.Cas.1915D, 1044; Bain Peanut Co. v. Pinson, 282 U.S. 499, 501 , 51 S.Ct. 228, 229; United States v. Lefkowitz, 285 U.S. 452, 467 , 52 S.Ct. 420, 424, 82 A.L.R. 775.
Peck & Co. v. Lowe, 247 U.S. 165 (1917):
"It is, however, equally clear that a general income tax is an excise tax laid upon persons or corporations with respect to their income: that is, a person or a corporation is selected out from the mass of the community by reason of the income possessed by him or it...
"This is brought out clearly by this court in Brushaber v. Union Pacific Railroad Co., 240 U.S. 1, and Stanton v. Baltic Mining Co., 240 U.S. 103. In the former case it was pointed out that the all-embracing power of taxation conferred upon Congress by the Constitution included two great classes, one indirect taxes or excises, and the other direct taxes, and that of apportionment with regard to direct taxes. It was held that the income tax in its nature is an excise; that is, it is a tax upon a person measured by his income...It was further held that the effect of the Sixteenth Amendment was not to change the nature of this tax or to take it out of the class of excises to which it belonged, but merely to make it impossible by any sort of reasoning thereafter to treat it as a direct tax because of the sources from which the income was derived."
[ Brief for the United States at 14-15 in Peck & Co. v. Lowe, 247 U.S. 165 (1917). Not in the ruling itself]