アメリカ合衆国憲法修正第16条(アメリカがっしゅうこくけんぽうしゅうせいだい16じょう、英:Sixteenth Amendment to the United States Constitution、あるいはAmendment XVI)は、1913年2月3日に批准された。この修正条項は、アメリカ合衆国議会が所得税を課す権限を大きく制限したポロック対農夫貸付信託会社事件(英語版)(1895年)判決を撤回させた。これによって、議会は諸州や国勢調査に関係せず所得税を課すことができるようになった。
^see Knowlton v. Moore ussc|178|41|1900 and Flint v. Stone Tracy Co. ussc|220|107|1911
^Commentary, James W. Ely, Jr., on the case of Springer v. United States, in answers.com, at [1]
^"Mr. Cockran's Final Effort", New York Times, Jan. 31, 1894[2]
^アメリカ合衆国最高裁判所の引用: "繰り返し言うが、その状況はあらゆる種類と性格の資産に由来する様々な「収入に課税する法案」によって適切に説明されている。それは1861年に法制化されたことに始まり、いわゆる南北戦争時代に続いた。「これら後半の税法」は「消費税、関税、付加金」という表題の下に区分けされることは疑いない。なぜならば、不動産あるいは動産に由来するものを含み「あらゆる収入に税負担を強いるものであるが」、その所有故に資産に直接課される税金ではないという程度の性格のものと考えられるからである。” Brushaber v. Union Pac. Railroad, ussc|240|1|1916, at 15 (「」内は補筆).
^Boris I. Bittker, Constitutional Limits on the Taxing Power of the Federal Government, The Tax Lawyer, Fall 1987, Vol. 41, No. 1, p. 3 (American Bar Ass'n) (Pollock case "was in effect reversed by the sixteenth amendment").
^「ブラッシャバー」裁判で最高裁が解釈したように、議会の所得に課税する権限は当初の憲法第1条第8節第1項に由来し、修正第16条ではない。修正第16条は単純に、所得税はそれが直接税であるという範囲で、州に分配されるべきという要求を排除した。Boris I. Bittker, Martin J. McMahon, Jr. & Lawrence A. Zelenak, Federal Income Taxation of Individuals, ch. 1, paragr. 1.01[1][a], Research Institute of America (2d ed. 2005), as retrieved from 2002 WL 1454829 (W. G. & L.).
^Penn Mutual Indemnity Co. v. Commissioner, 32 T.C. 653 at 659 (1959), aff'd, 277 F.2d 16, 60-1 U.S. Tax Cas. (CCH) paragr. 9389 (3d Cir. 1960).
^Order, Dec. 22, 2006, Murphy v. Internal Revenue Service and United States, United States Court of Appeals for the District of Columbia Circuit.
^460 F.3d 79, 2006-2 U.S. Tax Cas. (CCH) paragr. 50,476, 2006 WL 2411372 (D.C. Cir. August 22, 2006). In an unrelated matter, the Court had also granted the government's motion to dismiss Murphy's suit against the defendant "Internal Revenue Service." Under the doctrine of sovereign immunity the rule is that a taxpayer may sue The United States of America itself, not a government agency, officer, or employee (with few exceptions). The Court had stated: "Insofar as the Congress has waived sovereign immunity with respect to suits for tax refunds under uscsub|28|1346|a|1, that provision specifically contemplates only actions against the 'United States.' Therefore, we hold the IRS, unlike the United States, may not be sued eo nomine in this case." One exception to this rule is found in the United States Tax Court where the taxpayer sues the Commissioner of Internal Revenue (Murphy v. United States)
^Opinion on rehearing, July 3, 2007, Murphy v. Internal Revenue Service and United States, case no. 05-5139, United States Court of Appeals for the District of Columbia Circuit, 2007-2 U.S. Tax Cas. (CCH) paragr. 50,531 (D.C. Cir. 2007).
^Opinion on rehearing, July 3, 2007, p. 16, Murphy v. Internal Revenue Service and United States, case no. 05-5139, United States Court of Appeals for the District of Columbia Circuit, 2007-2 U.S. Tax Cas. (CCH) paragr. 50,531 (D.C. Cir. 2007).
^Opinion on rehearing, July 3, 2007, p. 5-6, Murphy v. Internal Revenue Service and United States, case no. 05-5139, United States Court of Appeals for the District of Columbia Circuit, 2007-2 U.S. Tax Cas. (CCH) paragr. 50,531 (D.C. Cir. 2007).