CRS Legal Sidebar Prepared for Members and Committees of Congress

Legal Sidebari

The Alien Enemy Act: History and Potential Use to Remove Members of International Criminal Cartels

February 18, 2025

On January 20, 2025, President Trump issued an executive order (E.O.) to declare a executive order (E.O.) declaring a national emergency pursuant to the International Emergency Economic Powers Act (IEEPA) to address the threat to U.S. national security posed by international cartels and certain transnational organizations. The E.O. statesstates that such organizationsorganizations are engaged in a destabilizing “"campaign of violence and terror throughout the Western Hemisphere”" and directsdirected the Secretary of State and other Cabinet members to designate certain international cartels and other organizations as foreign terrorist organizations or specially designated global terroristsforeign terrorist organizations or specially designated global terrorists under Executive Order 13224 for supporting international terrorism. On February 20, 2025, the Secretary of State, in consultation with the Attorney General and the Secretary of the Treasury, designated several international cartels as foreign terrorist organizations, including the organization known as Tren de Aragua ("TdA"). The E.O. also directed for supporting international terrorism. The E.O. also directs the Attorney General and Secretary of Homeland Security, in consultation with the Secretary of State, to make operational preparations within 14 days to implement any decision the President may make to invoke the Alien Enemy Act (also called the Alien Enemies Act) of 1798 to remove aliens designated as engaging in “"any qualifying invasion or predatory incursion against the territory of the United States by a qualifying actor.”" The E.O. does not define “"qualifying invasion”" or “"qualifying actor.”

" On March 14, 2025, President Trump invoked the Act, declaring that TdA "is perpetrating, attempting, and threatening an invasion or predatory incursion against the territory of the United States." The President's proclamation directed that "all Venezuelan citizens 14 years of age or older who are members of TdA, are within the United States, and are not actually naturalized or lawful permanent residents of the United States are liable to be apprehended, restrained, secured, and removed as Alien Enemies." On March 15, 2025, a lawsuit was filed, arguing, among other things, that the Act does not provide the President with the authority to remove individuals from the United States under these circumstances.

This Legal Sidebar provides a historical overview of the Alien Enemy Act and discusses the potential implications of invoking the actAct to remove members of international crime cartels and other transnational organizations from the United States. This Legal Sidebar also briefly discusses the current litigation regarding President Trump's proclamation invoking the Act to remove members of TdA. It is unclear how the invoked IEEPA authorities might interact with implementation of the Alien Enemy Act, and they are therefore outside the scope of this Legal Sidebar.

The Alien Enemy Act of 1798

The Alien Enemy Act of 1798 is a wartime measure that authorizesauthorizes the President, during a declared war or in the event of an “invasion” or “"invasion" or "predatory incursion”" perpetrated or threatened by “"any foreign nation or government,”" to issue regulations directing the conduct of or otherwise restraining citizens or nationals of the hostile nation or government. It was enacted as part of a set of national security measures known as the Alien and Sedition Acts meant to address tensions involving the French Republic. These laws included the Alien Act, the Sedition Act, and the Alien Enemy Act. Of these laws, only the Alien Enemy Act remains in force.

Congressional Research Service

https://crsreports.congress.gov

LSB11269

Congressional Research Service 2

The Alien Act empowered the President to order out of the country any alien whom he judged to be “"dangerous to the peace and safety of the United States”" or suspected to be concerned in any “"treasonable or secret machinations”" against the government. The law was controversial, with opponents arguingarguing that “"alien friends”" within the United States are entitled to due process of law and the same protection from the government as citizens and should be tried in court rather than summarily deported on suspicion of disloyalty. Skeptics arguedargued that such a measure could not be justified as a war power, even to prevent invasion. Proponents arguedargued that aliens within the United States owe merely temporary allegiance to the United States and are therefore not entitled to the same rights as citizens and that all governments have the right to deport aliens who pose a danger.

The Alien Enemy Act drew less debate. Neither James Madison nor Thomas Jefferson, who opposed the Alien Act, raised any objections, and even some opponents of the Alien Act in Congress were careful to clarifyclarify that they had no qualms with respect to the Alien Enemy Act. The absence of objection to the Alien Enemy Act by the same generation that drafted the Constitution has been held by the Supreme Court to provide evidence of both the act’s constitutionalityAct's constitutionality and the prevailing understanding of the legal principle underlying it—that is, the fundamentally different position held by aliens on the basis of their formal allegiance to a government with which the United States is at war.

Historical Invocation of the Alien Enemy Act

Unless Congress declares war, the President can invoke the Alien Enemy Act Act only upon his determination and proclamation that a foreign nation or government is conducting or threatening an “"invasion or predatory incursion”" into the territory of the United States. Presumably, this phrase was meantmeant to capture instances giving rise to the President’'s responsibility to repel an invasion by a foreign country without waiting for a congressional declaration of war. Upon such a proclamation, the government is authorized to detain or remove all citizens and nationals of the hostile country, age 14 and above, in accordance with regulations promulgated for that purpose and, unless suspected of engaging in hostilities, only after they are given adequate opportunity to depart of their own accord. The actAct is an exercise of the war power and rests on the presumptionpresumption that persons with allegiance to a hostile government pose a threat to the national security of the United States.

While the actAct would permit regulations affecting all persons falling within the statutory definition of “"alien enemy,”" it was the practice of the United States to intern only alien enemies who were found to constitute an active danger to the state, although other restrictions applied more broadly. Typically, alien enemies who were deemed to pose a threat have been interned were interned for the duration of the war and released or repatriated at the end of hostilities.

The Alien Enemy Act was first usedused during the War of 1812 and thereafter during World War I and World War II. At the outset of World War II, President Franklin D. Roosevelt initially invoked the actAct against aliens from Japan, Germany, and ItalyJapan, Germany, and Italy on the basis of an invasion or threatened invasion, but in each case, Congress declared war withindeclared war within a matter of daysdays. President Truman cited the declarations of war in his 1945 order for the removal of “"alien enemies now or hereafter interned within the continental limits of the United States … who shall be deemed by the Attorney General to be dangerous to the public peace and safety of the United States.”

"

At the outset of World War II, the internments were effected under civil authority of the Attorney General, who established “"prohibited areas”" in which no aliens of Japanese, Italian, or German descent were permitted to enter or remain, as well as a host of other restraints on affected aliens. Attorney General Francis Biddle created the Alien Enemy Control Unit to review the recommendations of hearing boards handling the cases of the more than 2,500 alien enemies in the temporary custody of the then-Immigration and Naturalization Service.

Congressional Research Service 3

In February 1942, President Roosevelt extended the enemy internment program to cover certain U.S. citizens as well as alien enemies and turned over the authority to prescribe “"military areas”" to the Secretary of War, who further delegated the responsibilities under the order with respect to the West Coast to the commanding general of the Western Defense Command. The new order, Executive Order 9066, amended the policy established under the earlier proclamations regarding alien enemies and restricted areas but did not rely on the authority of the Alien Enemy Act, as the previous proclamations had done. Although the Department of Justice denied that the transfer of authority to the Department of War was motivated by a desire to avoid constitutional issues with regard to the restriction or detention of U.S. citizens, the House Select Committee Investigating National Defense Migration found the shift in authority significant, as it appeared to rely on the nation’'s war powers directly and could find no support in the Alien Enemy Act with respect to U.S. citizens.

Congress enacted legislationlegislation proposed by the War Department providing for punishment for the knowing violation of any exclusion order issued pursuant to Executive Order 9066 or similar executive order. A policy of mass evacuationevacuation from the West Coast of persons of Japanese descent—citizens as well as aliens—followed, which soon transformed into a system of compulsive internment at “"relocation centers.”

" Prior Judicial Challenges

Aliens affected by orders promulgated under the actAct did not have recourse to the courts to object to internment or removal orders on the grounds that the determination that they posed a threat was not made in accordance with due process of law under the Fifth Amendment. Affected aliens, however, could bring habeas corpus petitions to challenge their status as alien enemies or whether there existed a state of war. Because all instancesinstances of the act’Act's use have occurred during a declared war, until now there has been no occasion for a court to examine whether an “"invasion or predatory incursion”" was underway.

The Supreme Court in Ludecke v. Watkins, a case concerning whether an alien enemy could be removed pursuant to the actAct although the war had ended, suggested its willingnesswillingness to leave the question of hostilities to the President, despite acknowledgingacknowledging that the powers provided by the actAct may be subject to abuse. It was not contested in Ludecke that the United States had declared war against Germany and that active hostilities had occurred. Ludecke, a German national, argued that he was entitled to relief because hostilities had ended and there was in effect no German government. The Court held that it did not have the power to disregard the views of the political branchesbranches about the continued danger posed by alien enemies in the aftermath of the war and that the petitioner had no right to judicial review of the Attorney General’'s determination that he was dangerous and subject to removal.

In a series of cases, the Supreme Court limited but did not explicitly strike down the internment program, which began under the Alien Enemy Act but was expanded to cover U.S. citizens pursuant to war powers. In the 1943 case Hirabayashi v. United States, the Supreme Court found the curfew imposed upon persons of Japanese ancestry to be constitutional as a valid wartime security measure, even as implemented against U.S. citizens. The Court emphasizedemphasized the importance of congressional ratification of the executive order that authorized curfews. In Korematsu v. United States (1944), the Supreme Court upheld the conviction of a U.S. citizen for remaining in his home despite the fact that it was located within a newly declared “"Military Area”" and was thus off-limits to persons of Japanese descent. The Court declineddeclined to consider the constitutionality of the detention itself, as Korematsu’'s conviction was for violating the exclusion order only.

In Ex parte Endo, decided the same day as Korematsu, the Supreme Court did not find adequate statutory underpinnings to support the internment of U.S. “"loyal citizens.”" The Court ruledruled that the authority to exclude persons of Japanese ancestry from declared military areas did not encompass the authority to detain “"concededly loyal”" Americans. Such authority, the Court determineddetermined, could not be implied from the power to protect against espionage and sabotage during wartime. The Court declareddeclared its obligation to

Congressional Research Service 4

interpret the wartime measure to allow for the “"greatest possible accommodation between … liberties and the exigencies of war,”" which in turn required an assumption that Congress “"intended to place no greater restraint on the citizen than was clearly and unmistakably indicated by the language they used.”

"

The Court later determineddetermined that Congress terminated World War II by joint resolution in 1951, eliminating the authority to remove previously interned enemy aliens. The Court in 2018 expressly recognized that Korematsu had been “overruled"overruled in the court of history”" and was “"gravely wrong the day it was decided.”

"

Members of International Cartels and Transnational Organizations as Alien Enemies Under the Act

and Current Litigation

As noted above, invocation of the Alien Enemy Act requiresrequires a declared war or an “"invasion or predatory incursion [that] is perpetrated, attempted, or threatened against the territory of the United States by any foreign nation or government.” Many journalists, commentators" Many journalists, commentators, and legal scholars have observedobserved that the actAct seems to contemplatecontemplate a state of hostilities or war with a foreign country, possibly precipitated by an invasion or threatened invasion by military forces, and not explicitly a threat posed by foreign drug cartels or gangs, for example. Some argueargue that the entry of drug cartels into the United States could potentially be treated as an invasion if evidence shows that they are committing or intend to commit acts of hostility against a state’'s inhabitants or officials “"on a scale or with a degree of organization that deliberately overthrows or curtails the lawful sovereignty of the state.”" Others make the case that constitutional references to “invasions”"invasions" that would justify invocation of war powers such as the Alien Enemy Act should be interpreted to mean an invasion by a hostile military force.

President Trump’'s executive order claimsclaims that international drug cartels “"functionally control, through a campaign of assassination, terror, rape, and brute force nearly all illegal traffic across the southern border of the United States.”" It also statesstates that they function as “"quasi-governmental entities, controlling nearly all aspects of society”" in certain areas of Mexico and threaten “"the safety of the American people, the security of the United States, and the stability of the international order in the Western Hemisphere.”" Under this view, the entry of and continued presence of persons associated with designated cartels may be deemed to be engaging in a “"qualified invasion or predatory incursion.”" This theory appears to be unprecedented and has not been subject to judicial review.

Although the Supreme Court has not directly addressed whether the unlawful entrance or presence of any alien may be treated as an invasion, lower courts have rejected as non-justiciable states’ invocation of the Invasion Clause (a part of the Guarantee Clause that provides that the federal government is responsible for protecting the states against invasion) to claim a right to receive federal assistance to manage the number of aliens within their territories. Some of these courts also expressed skepticism that “invasion” for purposes of the Invasion Clause means anything other than hostile military invasion. Other lower courts have found unpersuasive the argument that a state has the right to engage in war pursuant to Article I, Section 10, clause 3, to defend against an “invasion” lodged by transnational cartel members or by an “influx of illegal crossings.” One district court rejected Texas’s contention that its immigration enforcement efforts amounted to engaging in war.

Considerations for Congress

Although courts have generally deferred to the President’s determinations regarding exigencies affecting the national security or treated the question as political and non-justiciable, it is conceivable that courts might be unwilling to accept a determination that members of certain international cartels and other transnational organizations are invading the territory of the United States as an enemy force from a foreign country for purposes of the Alien Enemy Act. The Supreme Court has stated that executive actions to meet an exigency must be justified under the circumstances prevailing at the time and not

Congressional Research Service 5

LSB11269 · VERSION 1 · NEW

“mere executive fiat.” Congress may act to amend the Alien Enemy Act to the immigration context and to address perceived national security threats. There is one bill in the 119^th Congress to repeal the Alien Enemy Act, H.R. 630/S. 193. The Neighbors Not Enemies Act, a bill to repeal the Alien Enemy Act, has been introduced in successive Congresses since the 116^th Congress but has never been reported out of committee.

Author Information

Jennifer K. Elsea Legislative Attorney

Disclaimer

This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the United States Government, are not subject to copyright protection in the United States. Any CRS Report may be reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you wish to copy or otherwise use copyrighted material.

To establish that TdA is a foreign nation or government invading the United States, the March 2025 proclamation asserts that the group has infiltrated the Maduro government and is associated with regime-sponsored narco-terrorists. Further, the proclamation states, transnational criminal organizations have gained control over sufficient territory in Venezuela to bring about a "hybrid criminal state" that is "perpetrating an invasion of and predatory incursion into the United States." Separately, the proclamation asserts that TdA "has invaded the United States and continues to invade, attempt to invade, and threaten to invade the country; perpetrated irregular warfare within the country; and used drug trafficking as a weapon against our citizens." TdA, according to the proclamation, is conducting these hostile activities both directly and under the direction of the Maduro regime. Accordingly, the proclamation finds that an invasion or predatory incursion against U.S. territory is occurring and that, because TdA members are "chargeable with hostility," they will not be accorded the opportunity under the statute to depart voluntarily. Any property associated with the group's hostile activities is subject to forfeiture.

As previously noted, a group of plaintiffs (Venezuelan men in immigration custody) filed a class action complaint and petition for writ of habeas corpus with the U.S. District Court for the District of Columbia challenging the government's use of the Act in this circumstance. The plaintiffs also filed an emergency application for a temporary restraining order. On March 15, 2025, the district court issued a temporary restraining order to enjoin for 14 days the removal of five Venezuelans who are parties to the litigation and then expanded the order to certify the class of Venezuelans who are detained and potentially removable under the proclamation. It was reported the following day that the Trump Administration removed more than 200 aliens to El Salvador, purportedly as alien enemies.

The government appealed both orders and asked for an emergency stay during appeal at the U.S. Court of Appeals for the D.C. Circuit, contesting venue and asserting, among other things, that it is likely to prevail on the merits. A divided panel of the D.C. Circuit denied the stay of the temporary injunction, meaning the government continues to be enjoined from carrying out more removals under the Act. The government has filed a request for an administrative stay and an application to vacate the district court judge's decision with the Supreme Court.

Considerations for Congress

Courts have generally deferred to the President's determinations regarding exigencies affecting the national security or, according to commentators, treated the question as political and non-justiciable. Yet it is conceivable that courts might be unwilling to accept a determination that members of certain international cartels and other transnational organizations are invading the territory of the United States as an enemy force from a foreign country for purposes of the Alien Enemy Act. The Supreme Court has held that, as opposed to "mere executive fiat," executive actions to meet an exigency must be justified under the circumstances prevailing at the time. The Court further explained, "What are the allowable limits of military discretion, and whether or not they have been overstepped in a particular case, are judicial questions." Congress may determine that such judicial questions and answers are the best way to clarify any ambiguity regarding the Alien Enemy Act. Alternatively, Congress may act to amend the Alien Enemy Act to adapt it to the immigration context and to address perceived national security threats. Conversely, Congress may consider limiting the Act by providing a restrictive definition for "invasion" and "predatory incursion" to clarify that such a situation is one in which the rules of war apply (as the Wilson Administration interpreted it).

A bill in the 119th Congress would repeal the Alien Enemy Act, H.R. 630/S. 193. This bill, the Neighbors Not Enemies Act, has been introduced in successive Congresses since the 116th Congress but has never been reported out of committee.