

Since Donald Trump invoked the Alien Enemies Act of 1798 (AEA) as a tool for peacetime detention and deportation in March of this year, there has been extensive litigation over the legality of that action. The AEA allows detention and deportation of non-citizens from relevant countries (including legal immigrants) “[w]henever 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.” Trump has tried to use the AEA to deport Venezuelans the administration claims are members of the Tren de Aragua (TdA) drug gang.
Multiple federal district courts and the US Court of Appeals for the Fifth Circuit, have ruled that Trump’s actions are illegal because illegal migration and drug smuggling of the kind TdA engages in do not qualify as a war, invasion, or predatory incursion. I think overwhelming evidence supports these conclusions, evidence I document in detail in my new article “Immigration is Not Invasion.” But litigation continues. The Fifth Circuit is going to rehear its decision en banc (before all 17 active judges of that court), and one district court has (incorrectly) ruled that TdA’s actions qualify as a “predatory incursion.”
In all the litigation and commentary on this issue up to now, one important issue seems to have been overlooked (including by me!): whether Trump’s interpretation of the AEA is barred by the “major questions doctrine” (MQD). I only became aware of it when one of my fall semester Constitutional Law I students – David Koster – raised the possibility. What follows is my own take on the issue, and is solely my responsibility. But David deserves the credit for coming up with the idea in the first place.
The major questions doctrine requires Congress to “speak clearly” when authorizing the executive to make “decisions of vast economic and political significance.” If the statute isn’t clear, courts must reject the executive’s assertion of power.
The sweeping authority Trump claims under the AEA seems major enough to qualify as a matter of “vast economic and political significance.” If the AEA can be used to deport migrants from any country that is a source of illegal migrants or cross-border drug smuggling, many millions of immigrants (including many legal ones) could potentially be subject to detention and deportation at any time the executive chooses. For example, the single largest immigrant population in the US is that from Mexico, a total of about 11.4 million people. Mexico is obviously a source of both drug smuggling and illegal migrants. The same is true of most other countries with large immigrant populations in the US, such as Cuba and the nations of Central America. If illegal migration and drug smuggling qualify as “invasions” or “predatory incursions,” we are under constant invasion (or predatory incursion) from dozens of countries around the world!
To be sure, the AEA also requires that the invasion or predatory incursion be perpetrated by a “foreign nation or government.” But if the tenuous ties (assessed as very weak by the Trump Administration’s own intelligence agencies) between the Venezuelan government and TdA are enough to qualify, similar claims can be made about the government of virtually any other nation with a large immigrant population in this country. Mexican officials, for example, likely have at least some ties to drug smugglers. The same is likely true of government officials in various Central American nations, and elsewhere.
The power to detain and deport millions of migrants (including legal ones) at any time, and with little due process is one with obviously vast economic and political effects. Not just on migrants themselves, but on American citizens who have family, business, and other connections with these immigrants. If the authority is used on any significant scale, it would also seriously damage the US economy.
A key factor the Supreme Court uses in assessing major questions cases is whether the executive’s claim to authority under the relevant statute is “unprecedented.” Here, it very obviously is. The AEA has been around for 227 years. And in all that time, it has previously invoked on only three occasions: the War of 1812, World War I, and World War II – all major wars against foreign governments. There is zero precedent for its use to counter anything like illegal migration or drug smuggling. As discussed more fully in my article, there is also no evidence that the framers of the law ever contemplated its use for such purposes.
If MQD does apply here, it provides a strong additional justification for rejecting the administration’s position. As explained in detail in my article, and the Fifth Circuit amicus brief I coauthored on behalf of the Brennan Center, the Cato Institute, and others, textual and historical evidence overwhelmingly demonstrates that “invasion” and “predatory incursion” refer to military attacks. At the very least, it is far from clear that they encompass illegal migration or drug smuggling. And if things are unclear, MQD requires courts to rule against the executive’s assertion that it has been delegated a vast power.
The Trump Administration could argue that the major questions doctrine doesn’t apply to delegations of power to the president, as opposed to delegations to agencies. But that’s an extremely weak argument that has been rejected by multiple courts of appeals.
The Administration could also argue that major questions doctrine doesn’t apply to “foreign affairs” delegations. The Supreme Court has never adopted any such exception. And several previous uses of the major questions doctrine have applied to policies with significant foreign policy effects. For example, in West Virginia v. EPA, the Court used major questions doctrine to strike down a Biden policy addressing climate change; climate change is obviously an issue with vast foreign policy significance. In Biden v. Nebraska, the student loan case, the Court applied the doctrine to strike down Biden’s massive student loan forgiveness program. They did so despite the fact that Biden claimed the authority in question comes from the HEROES Act, legislation whose original purpose was in large part to provide loan forgiveness to members of the military serving abroad during wars and other conflicts (they are the “heroes” from whom the act gets its name).
Moreover, mass detention and deportation of migrants is far from a pure foreign affairs issue. Its most immediate effect is on migrants living in the United States, many of whom have been here for years and are integrated into our economy or society. It also has vast effects on American citizens. Invocations of the AEA obviously do have some impact on foreign affairs. But the same is true of many, perhaps most, major domestic policies. That doesn’t mean such policies are exempt from MQD scrutiny.
Another issue that might arise here is the claim that the AEA is not a true delegation because the president has inherent authority over immigration. The Constitution doesn’t specify which branch of government has the power to restrict migration (probably because the federal government was not originally understood to have that power at all). But the Supreme Court has repeatedly held that this power is a legislative authority, going all the way back to the Chinese Exclusion Case of 1889, the first decision holding that the federal government has a general power to restrict migration, and in the process also ruled that the authority belongs to “the legislative department.” Holding that the president has his own authority to restrict migration would also upend the extensive system of immigration laws enacted by Congress over the last century and more, potentially empowering the president to just sweep it aside, at will.
In sum, the major questions doctrine clearly applies to the Trump Administration’s assertion of power under the Alien Enemies Act. And if there is any ambiguity about whether the AEA gives the executive the sweeping power it claims, MQD requires a ruling against the government.
As noted above, I think courts can and should rule against the administration based on the text and history of the law alone, and several already have. But if judges conclude the AEA is unclear, the major questions doctrine requires resolving that ambiguity against the administration.
For those keeping score, I said much the same thing about the use of the MQD in various Biden-era cases, including loan forgiveness, the eviction moratorium case, and the vaccine mandate case. I have argued that MQD is an important tool for curbing executive power grabs under both Democratic and Republican administrations. If necessary, it should be used here, too.
