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The Alien Enemies Act Is Outdated, Dangerous, and Ripe for Abuse

Donald Trump has threatened to use the 1798 law to conduct mass deportations with little due process. Congress should repeal it.

February 28, 2024

This article was first published by Just Security.

Former President Donald Trump has promised voters that, if re-elected, he would “immediately” invoke the Alien Enemies Act to effect mass deportations of non-citizens from Mexico. He reportedly plans to apply the law broadly, targeting non‑citizens who are not suspected of any cartel involvement or narcotics trafficking. By using the Alien Enemies Act, a law enacted pursuant to Congress’s constitutional war powers, Trump could conduct the deportations summarily, without any of the hearings or other process typically accorded to non-citizens in peacetime and under immigration law.

As troubling as the prospect of mass, summary deportations may be, reactions to Trump’s proposed use of the Alien Enemies Act have in many cases underestimated the risk at hand. Journalists and commentators have expressed doubt about whether the Alien Enemies Act could apply, citing the law’s requirement that the United States be in a declared war or face an “invasion or predatory incursion” perpetrated by a “foreign nation or government.” Some have suggested that the courts would strike down Trump’s scheme on those grounds.

These commentators are correct, of course, on the merits of whether an invasion exists or cartels constitute a foreign government. But the courts’ history of treating “political questions” as “nonjusticiable” suggests that judges are unlikely to address these arguments on the merits. The courts would likely avoid opining on the presence or absence of an invasion or predatory incursion, and they are even less likely to probe whether the perpetrator of the supposed invasion or incursion is a foreign nation or government.

The courts’ hesitance to weigh in on these questions heightens the risk that Trump will invoke the Alien Enemies Act despite its clear inapplicability. But that does not mean mass deportations based on the wartime authority are inevitable. Congress can change the law — and even if Congress fails to do so, the courts may strike down an invocation of the Alien Enemies Act under modern due process and equal protection law, justiciable grounds for checking abusive presidential action.

Alien Enemies Act

In 1798, during the undeclared “Quasi-War” with France, Congress enacted the notorious Alien and Sedition Acts. Known primarily for their infringement on the freedom of speech, three of the four Alien and Sedition Acts were allowed to lapse or were repealed shortly after their enactment. Only the Alien Enemies Act, which had no sunset date, continues to exist on the books.

The Alien Enemies Act, largely unmodified since 1798, empowers the president to detain and deport non‑citizens in times of a declared war or presidentially proclaimed “invasion” or “predatory incursion” by a foreign nation or government. The law permits the president to target a broad swath of non-citizens, including all “natives, citizens, denizens, or subjects” of the hostile nation or government. It does not distinguish between non-citizens who are unlawfully present in the United States and non‑citizens with established legal status, such as permanent residents. Nor does the law distinguish between “loyal” and “disloyal” non-citizens. The Alien Enemies Act does not require the president to establish or even believe that detained or deported non-citizens pose a threat to the national security. Rather, it is enough that a non-citizen was born in, has the passport of, or resides in the wrong country.

Because the Alien Enemies Act does not require the president to show any misconduct or threat posed by targeted non-citizens, the law does not afford non-citizens an opportunity to present evidence of their loyalty to the United States. There is no procedure for non‑citizens to appeal the president’s decision to detain or deport them. When detained non-citizens have brought habeas cases, the courts have generally limited their review to whether the detainee was, in fact, a non-citizen with the requisite connection — place of birth, citizenship, or residency — to the hostile nation or government.

The Alien Enemies Act has been used three times, each involving a declared war: the War of 1812, World War I, and World War II. The law was a key authority behind the ignominious policy of Japanese internment, as well as the lesser‑known internment of German and Italian civilians during World War II.

Invasion or Predatory Incursion

Because the Alien Enemies Act has only been used in major conflicts, where Congress declared war, there is no case law interpreting the meaning of “invasion” or “predatory incursion” as those terms appear in the statute. Nevertheless, the meaning of the terms is clear from the legislative history, litigation addressing the law’s constitutionality, and the historical use of the terms.

Debates and litigation over the Alien Enemies Act show that the authority was meant for times of “war or threatened war.” The law’s application only in times of “actual hostility” distinguished it from the contemporaneous Alien Friends Act, another part of the Alien and Sedition Acts that was widely criticized as unconstitutional before it lapsed in 1801. Both when enacted and in subsequent litigation, the Alien Enemies Act’s proponents defended its constitutionality on the ground that the “rules of war under the laws of nations” rendered a belligerent’s citizens “liable to be treated as prisoners of war” and thus subject to detention or deportation.

It follows that an “invasion” or “predatory incursion” must amount to open hostilities or war. This is consistent with how the terms were used historically. In a discussion of the Alien and Sedition Acts, James Madison wrote that “Invasion is an operation of war.” In subsequent years, the term “predatory incursion” was used to describe “hostile” and “warlike” attacks by Native American tribes. Most significantly, President Franklin D. Roosevelt invoked the Alien Enemies Act before Congress convened to declare war on Japan, Germany, and Italy.  He did so on the basis of Japan’s “invasion” of Pearl Harbor, as well as Germany and Italy’s threatened “invasion or predatory incursion” upon U.S. territory. These terms referred to armed activity implicating the law of war — a far cry from narcotics trafficking, let alone migration.

To some extent, the courts have endorsed this analysis. In the 1990s, courts across the country dismissed a slate of cases in which states argued that the federal government had violated Article IV of the Constitution by failing to prevent a supposed “Invasion” of undocumented migrants. In dismissing the cases, several of the courts suggested that an invasion must involve “military” action or “armed hostility from another political entity.”

But none of the courts actually decided their cases on that basis. Instead of ruling that unlawful migration was not, in fact, an “invasion,” the courts determined that they had no institutional role in passing judgment on whether an invasion was occurring. According to the courts, the presence or absence of an invasion was a nonjusticiable “political question” with no judicially “manageable standards” for resolution. To opine on the subject would be to “disregard the constitutional duties that are the specific responsibility of other branches of government,” namely, Congress and the president.

The courts of the 2020s appear no bolder than their 1990s predecessors. In a pending case regarding Texas’s authority to construct a 1,000-foot barrier in the Rio Grande, Texas has resurfaced the migration‑as‑invasion theory of the Constitution. Instead of rejecting Texas’s theory on the merits, the courts have thus far said that the political question doctrine “bars consideration” of the argument.

If the courts will not substantively reject a state’s invasion argument — even when it is contested by the executive branch in litigation — it is difficult to envision the courts substantively rejecting the president’s invasion argument.

Foreign Nation or Government

The War of 1812, World War I, and World War II — the three declared wars in which presidents invoked the Alien Enemies Act — were all fought against conventional state actors. There was no ambiguity about whether these adversaries constituted a “foreign nation or government,” as required by the Alien Enemies Act. The same cannot be said about Mexican cartels.

It may seem obvious that Mexican cartels do not constitute a foreign nation or government. The cartels are non-state actors with criminal, not political, ambitions. The internationally recognized Mexican government under President Andrés Manuel López Obrador is actively working to suppress the cartels, with U.S. support. No state, let alone the United States, engages in diplomatic relations with the cartels, nor do the cartels purport to maintain diplomatic relations.

Unfortunately, these facts may not be enough to guarantee that the courts would second-guess a president’s decision to recognize a cartel as a government — whether as the de facto government of territory beyond the Mexican government’s effective control or even, as Trump allies have suggested, as a part of the Mexican government via bribes to and influence over its officials.

long line of cases endorses the principle that “[w]ho is the sovereign, de jure or de facto, of a territory is not a judicial, but is a political question, the determination of which by the legislative and executive departments . . . conclusively binds the judges.” Indeed, in 1918, the Supreme Court relied on this principle in a case involving the acts of a military regime in Mexico. Because President Wilson had recognized General José Venustiano Carranza as the de facto and later the de jure leader of Mexico, the Carranza regime had to be “accepted [by the courts] as the legitimate government of Mexico.”

More recently, in Zivotofsky v. Kerry, the Supreme Court held that recognition of a foreign government is “the exclusive prerogative of the Executive.” In other words, “it is for the President alone” — not even the president in conjunction with Congress — “to make the specific decision of what foreign power he will recognize as legitimate.” A majority of the Court reached this conclusion over an objection by Justice Scalia that giving the president exclusive recognition power could cause mischief in matters of war and peace.

More than two centuries’ worth of case law casts doubt on whether the courts would reject Trump’s recognition of a cartel “government” in Mexico. In light of Zivotofsky, it is unclear that even Congress could override such a recognition decision, notwithstanding the immense damage to U.S.-Mexico relations that would ensue if Trump recognized a cartel as the de facto government of, say, the Mexican state of Sinaloa.

A Potential Limit to the Political Question Doctrine

Although the Supreme Court has not identified any explicit exceptions to the political question doctrine, one of its cases from the 1930s, Sterling v. Constantin, gestures toward a constitutional backstop: the president’s constitutional obligation to “faithfully execute” the law. While acknowledging that this obligation vests the president with substantial discretion, the Court held that “[t]he nature of the power also necessarily implies that there is a permitted range of honest judgment” within which the president must operate.

If Trump, as president, were to proclaim an “invasion” or “predatory incursion” on the southern border, that would arguably fall short of his duty to act “in good faith” and fall beyond his allowable discretion. The proclamation would have been made cynically — for the sole purpose of unlocking the Alien Enemies Act’s vast detention and deportation powers — rather than in tandem with a military operation to repel an armed attack by a foreign power, a withdrawal of U.S. diplomatic recognition from the government of Mexico, or other acts consistent with the notion that a cartel were a “foreign nation or government.” Moreover, and as discussed, migration and narcotics trafficking are worlds apart from the kind of “war or threatened war” that the Alien Enemies Act was meant to address.

A similar argument could be made about any recognition of cartels as the de facto government of all or part of Mexico. If Trump were to recognize a cartel as a de facto government, it would surely not be for the purpose of sending and receiving diplomats or concluding treaties — the core of the president’s recognition power, which stems from the Constitution’s Reception Clause, Ambassadors Clause, and Treaty Clause in Article II. It would, instead, be a cynical play to unlock the powers of the Alien Enemies Act. Trump’s advisers have more or less said as much, admitting to journalists that the Trump team has cooked up a “very convoluted and crazy” theory of why cartels constitute a government, for the specific purpose of invoking the Alien Enemies Act.

Moreover, in this case, the president’s pronouncements regarding the existence of an invasion or predatory incursion, as well as his recognition of a new foreign government, would have immediate and concrete effects on the liberties of people inside the United States who enjoy constitutional protections. As Justice O’Connor wrote in Hamdi v. Rumsfeld, “[w]hatever power the United States Constitution envisions for the Executive in its exchanges with other nations or with enemy organizations in times of conflict, it most assuredly envisions a role for all three branches when individual liberties are at stake.” To give meaning to this language and to the rule in Sterling, the courts should eschew their conventional political question analysis and reject any Alien Enemies Act invocation based on migration-as-invasion or cartel-as-government theories.

Other Options for Addressing the Alien Enemies Act

While courts can and should reject the application of the Alien Enemies Act for the reasons stated above, it would be wise not count on the courts to depart from their traditional application of the political question doctrine. Instead, we should be considering what other arguments can be raised by or on behalf of non-citizens who could be targeted under the Alien Enemies Act.

The Alien Enemies Act was last upheld in 1948, four short years after the Supreme Court upheld the shameful policy of interning Japanese Americans in Korematsu v. United States. Between 1948 and today, constitutional due process, equal protection, and the law of war have progressed tremendously. Cases like United States v. Salerno and Zadvydas v. Davis have clarified that detention without trial is a “limited exception” that warrants “numerous procedural safeguards” and cannot extend for an indefinite period, even for non-citizens. Other cases have emphasized non-citizens’ “weighty” liberty interest in remaining stateside and their entitlement to a “fair hearing” with adequate procedures when threatened with deportation. The now-foundational Mathews v. Eldridge framework for assessing the requirements of procedural due process did not even exist in 1948.

The Alien Enemies Act was also upheld before the Supreme Court decided Bolling v. Sharpe, the first case to establish that the guarantees of the Equal Protection Clause, which binds the states, are incorporated against and apply to the federal government. It was upheld before courts began striking down statutes prohibiting certain non-citizens from owning land, or so-called “alien land laws,” because of their de facto classifications “on the basis of race” that were neither an “accurate or reasonable method for distinguishing between loyal and disloyal persons.” Korematsu, for its part, has been recast as part of our constitutional anti-canon, alongside cases like Dred Scott v. Sandford and Plessy v. Ferguson. Congress recognized the “fundamental injustice” of Japanese internment and enacted a reparations regime for internees, including non-citizen permanent residents.

The changes to domestic law have been complemented by changes to the law of war, the supposed basis for the Alien Enemies Act’s constitutionality vis-à-vis the Alien Friends Act. The Geneva Conventions now prohibit states from detaining or deporting non-citizens based on “the mere fact that a person is a subject of an enemy Power”; they require individualized suspicion that a non-citizen “represents a real threat to [the state’s] present or future security.”

Under these new understandings, courts might well find that the Alien Enemies Act is unconstitutional, even if they are unwilling to second-guess what constitutes an invasion, predatory incursion, or foreign nation or government.

Ultimately, though, the most certain safeguard against Trump’s threatened actions is for Congress to repeal this outdated, dangerous legislation. (Conventional immigration law, with its procedural protections, would still permit the deportation of non-citizens on security and related grounds.)  The Neighbors Not Enemies Act, a clean repeal bill, has been introduced in both the House and Senate. It deserves widespread and bipartisan support.