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The US District Court for the Southern District of Texas has now weighed in on the Trump Administration’s invocation of the Alien Enemies Act of 1798, declaring that Tren de Aragua, is a “designated Foreign Terrorist Organization[,] . . . perpetrating, attempting, and threatening an invasion or predatory incursion against the territory of the United States.” With so much speculation and so many assumptions being made, I want to cut through the BS and get to the truth. Before summarizing the opinion, though, a little background is in order.

The Alien Enemies Act of 1798 is a federal law that grants the president “wartime authority” to detain or deport non-U.S. citizens of enemy countries. It was enacted in 1798 as part of a series of laws known as the Alien and Sedition Acts, aimed at addressing national security concerns during a period of tension with France. The Act can be invoked during a declared war, a perpetrated, attempted, or threatened invasion, or a “predatory incursion” against U.S. territory. Those terms are key to understanding the scope of the Act of a President’s authority to invoke it.

In summary, the Act allows the President to target citizens of a hostile nation or government who are not US citizens in a time of war for detention or deportation, and the this law permits these actions to be taken without a court hearing, based solely on citizenship or country of origin of the targeted persons.

Legal scholars question whether a law that targets people based on the citizenship or country of origin would withstand a constitutional challenge. My understanding is (not having reviewed the relevant caselaw) that the Act has not been challenged in court on constitutional grounds, and the present case involving Venezuelan immigrants does not include a constitutional challenge. Therefore, the constitutionality of the Act has not been addressed.

The Act has been invoked only three times in U.S. history: during the War of 1812, World War I, and World War II. This law was the authority cited for the detentions, expulsions, and restrictions targeting German, Austro-Hungarian, Japanese, and Italian immigrants based on ancestry during WWII, and it was the justification alleged for Japanese internment.

The Act is a war power. It is triggered by 1) a congressional declaration of war; 2) a presidential determination of threatened or actual invasion; or 3) a presidential determination of threatened or actual “predatory incursion”. Only Congress can declare war, but the President has the authority to repel sudden attacks (invasions or “predatory incursions”).

Obviously, the ability of a President to invoke the Act without an act Congress requires an invasion or “predatory incursion”. Congressional intent can be gleaned from the way those terms were used in the late 1700’s. According to the Brennan Center for Justice,

“In the Constitution and other late-1700s statutes, the term invasion is used literally, typically to refer to large-scale attacks. The term predatory incursion is also used literally in writings of that period to refer to slightly smaller attacks like the 1781 Raid on Richmond led by American defector Benedict Arnold.”

See The Alien Enemies Act, Explained, Brennan Center for Justice, Katherine Yon Ebright, May 1, 2025

Recent groups have encouraged a non-literal interpretation of the terms to address illegal immigration and trafficking “based on a migrant ‘invasion’ or ‘predatory incursion’ perpetrated by a cartel alleged to be acting as a de facto foreign government.” That creative reading of the law, however, “is at odds with centuries of legislative, presidential, and judicial practice, all of which confirm that the Alien Enemies Act is a wartime authority. (See The Alien Enemies Act, Explained)

The Act has only ever been used in the context of war declared by Congress. President Truman’s invocation of the Act to detain prisoners as late as 1951 was allowed with deference on the presidential determination of when a war terminates (WWII), but the Act has never been used in the history of the nation outside of a declared war.

The Brennan Center for Justice, a progressive non-profit think tank, notes that Fifth Amendment protections apply against discrimination on the basis of race, ethnicity, nationality, etc. For these reasons, they say, courts and presidents have apologized for the Japanese interment during WWII, and scholars have generally held that the Japanese interment was mistaken, if not blatantly unconstitutional. Other legal issues undermine the validity of the law as well. (See The Alien Enemies Act, Explained)  

With that background and explanation of the Alien Enemies Act of 1798. Let’s turn to the opinion that was handed down On May 1, 2025. The opinion is authored by a conservative judge (who happens to be an Evangelical Christian) appointed by President Trump. It recounts the history of the Act with detail and technical fluidity that I will try to explain by focusing on the key language. For the legal nerds among us, you can read the 36-page opinion yourself. (See J.A.V. et al., v. Donald Trump, Civil Action No. 1:25-CV-072 (So. Dist. TX)(5-1-2-25))

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