Whenever there is a declared war between the United States and any foreign nation or government, or any invasion or predatory incursion is perpetrated, attempted, or threatened against the territory of the United States by any foreign nation or government, and the President makes public proclamation of the event, all natives, citizens, denizens, or subjects of the hostile nation or government, being of the age of fourteen years and upward, who shall be within the United States and not actually naturalized, shall be liable to be apprehended, restrained, secured, and removed as alien enemies. The President is authorized in any such event, by his proclamation thereof, or other public act, to direct the conduct to be observed on the part of the United States, toward the aliens who become so liable; the manner and degree of the restraint to which they shall be subject and in what cases, and upon what security their residence shall be permitted, and to provide for the removal of those who, not being permitted to reside within the United States, refuse or neglect to depart therefrom; and to establish any other regulations which are found necessary in the premises and for the public safety.
Notes of Decisions
Cited in
87
cases (
20 in the last 5 years), 1942–2026 · leading case:
Trump v. J. G. G., 604 U.S. 670 (2025).
Trump v. J. G. G., 604 U.S. 670 (2025).
· cites it 3× “§4067, 50 U. S. C. §21 , to detain and remove Venezuelan nationals “who are members of TdA.”
Hamdi v. Rumsfeld, 542 U.S. 507 (2004).
· cites it 2× “4067, 50 U.S.C. § 21 (Alien Enemy Act). That captivity may be consistent with the principles of international law does not prove that it also complies with the restrictions that the Constitution places on the American Government's treatment of its own citizens.”
A.A.R.P. v. Trump, 605 U.S. 91 (2025).
“§4067, 50 U. S. C. §21 , to remove Venezuelan na- tionals who are members of Tren de Aragua (TdA), a desig- nated foreign terrorist organization.”
Harisiades v. Shaughnessy, 342 U.S. 580 (1951).
· cites it 2× “[I]n strict law, a State can expel even domiciled aliens without so much as giving the reasons, the refusal of the expelling State to supply the reasons for expulsion to the home State of the expelled alien does not constitute an illegal, but only a very unfriendly act.”
Ludecke v. Watkins, 335 U.S. 160 (1948).
· cites it 2× “531 , 50 U.S.C. § 21 .) This Alien Enemy Act has remained the law of the land, virtually unchanged since 1798.”
Lopez-Aguilar v. Marion Cnty. Sheriff's Dep't, 296 F. Supp. 3d 959 (S.D. Ind. 2017).
“577 , 50 U.S.C. § 21 , the only still-surviving component of the widely condemned Alien and Sedition Acts of 1798, which authorized such treatment only as to noncitizens who were subjects or citizens of a nation between which and the United States war had been declared or had…”
Guessefeldt v. McGrath, 342 U.S. 308 (1952).
· cites it 2× “In World War I, Congress specifically exempted "alien enemies" from the draft, a context in which the term "alien enemy" would be meaningless if it did not include nationals of enemy nations residing in this country.”
Johnson v. Eisentrager, 339 U.S. 763 (1950).
“577 , as amended, 50 U. S. C. § 21 . And it is to be noted that, while the Alien and Sedition Acts of that year provoked a reaction which helped sweep the party of Mr.”
Ex Parte Kawato, 317 U.S. 69 (1942).
· cites it 2× “8 The President has issued a Proclamation taking certain steps with reference to alien enemies under the Alien Enemy Act of 1798 as amended, 50 U. S. C. § 21 , but this Proclamation has no bearing on the power of the President under the Trading with the Enemy Act.”
United States Ex Rel. Eichenlaub v. Shaughnessy, 338 U.S. 521 (1950).
· cites it 2× “2, 870, see 50 U. S. C. § 21 . It thus raises questions as to the "enemy" status of an alien born in Lorraine, which at the time of his birth was a part of Germany, but at the time of his arrest was a part of France.”
Fadi Maqaleh v. Chuck Hagel, 738 F.3d 312 (D.C. Cir. 2013).
“577 (codified at 50 U.S.C. § 21 (2006)), the President may summarily detain any person who is a citizen of a nation with which the United States is at war.”
Citizens Prot. League v. Clark, 155 F.2d 290 (D.C. Cir. 1946).
· cites it 2× “matter of law defendant-appellee was entitled to judgment. The judgments of the District Court were correct.”
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