Overview

The Alien Enemies Act (50 U.S.C. §§ 21–24) is the only surviving statute from the Alien and Sedition Acts of 1798. Originally enacted during the quasi-war with France, it authorizes the President to detain and remove nationals of a hostile nation during wartime. The Trump administration’s 2025 invocation of this Act for peacetime immigration enforcement is historically unprecedented and legally contested.

Text of the Statute (Current Codification)

50 U.S.C. § 21:

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.

Historical Invocations

World War II Application

The most extensive use of the Alien Enemies Act occurred during World War II, when it was used alongside Executive Order 9066 to authorize the internment of Japanese, German, and Italian nationals (and in the case of Japanese internment, U.S. citizens of Japanese descent — which was later recognized as a grave injustice).

Ludecke v. Watkins, 335 U.S. 160 (1948): The Supreme Court upheld the President’s authority under the Alien Enemies Act to order the removal of a German national during the proclaimed state of war. However, the case was decided during an actual declared war, and Justice Black’s dissent warned against unlimited executive detention power.

The 2025 Invocation

What the Administration Did

The Trump administration invoked the Alien Enemies Act to authorize the detention and removal of foreign nationals alleged to be associated with Tren de Aragua (a Venezuelan criminal organization) and other transnational gangs. The administration’s theory:

• Tren de Aragua constitutes a foreign entity perpetrating an “invasion or predatory incursion” against U.S. territory
• This triggers the President’s authority under the Alien Enemies Act
• Individuals identified as associated with the organization can be detained and removed without standard INA proceedings

Legal Problems

No declared war. The statute’s primary trigger is a “declared war.” The United States has not declared war on Venezuela or any other nation relevant to the invocations.

“Invasion or predatory incursion” — stretched beyond historical meaning. The statutory alternative to declared war — “invasion or predatory incursion… by any foreign nation or government” — has historically meant military action by a foreign government against U.S. territory. Extending this to cover the activities of criminal gangs requires an interpretation far beyond the statute’s historical application.

Class-based targeting. The Act authorizes action against nationals of a hostile nation — not against individuals based on alleged gang membership. Using the Act to target specific individuals based on suspected criminal associations rather than nationality raises due process concerns.

No individualized process. The Act as invoked provided no individualized determination that each person removed actually had any connection to Tren de Aragua or any other criminal organization.

Peacetime application. The Act has never been upheld by the Supreme Court in a non-war context. Ludecke v. Watkins was decided during a declared war.

Court Responses

• Federal courts issued emergency stays and injunctions
• Courts questioned whether the Act could be invoked outside a declared war
• The Supreme Court addressed emergency applications
• Courts ordered the government to facilitate the return of individuals removed under the Act in violation of court orders

Due Process and the Alien Enemies Act

Even if the Alien Enemies Act is validly invoked, individuals subject to it retain due process rights under the Fifth Amendment:

• The right to challenge the factual basis for their classification as “alien enemies”
• The right to an individualized determination — not blanket classification based on nationality
• The right to judicial review (habeas corpus) of their detention
• The right not to be removed to a country where they face torture (Convention Against Torture obligations)

The Japanese Internment during World War II — justified in part under the Alien Enemies Act and upheld in Korematsu v. United States (1944) — is now universally recognized as one of the gravest constitutional violations in American history. The Supreme Court formally repudiated Korematsu in Trump v. Hawaii, 585 U.S. 667 (2018), calling it “gravely wrong the day it was decided.”

Key Legal Principles

• The Alien Enemies Act has historically been a wartime statute — its application in peacetime is unprecedented
• Even in wartime, individuals have due process rights including the right to contest their classification
• The Japanese Internment — the most extensive use of the Act — is now recognized as a constitutional atrocity
• Courts are actively reviewing whether the 2025 invocations are lawful
• The Act targets nationals of hostile nations, not individuals based on suspected criminal associations