() The outcome of what could be a lengthy legal battle involving President Donald Trump’s right to invoke a 227-year-old wartime law could establish an important precedent in how quickly and under what circumstances migrants can be deported from the United States.

The White House said Monday that 137 of the 261 migrants who were deported to El Salvador on Sunday under the Alien Enemies Act of 1798, which has only been invoked three times, most recently during World War II.

White House press secretary Karoline Leavitt told reporters Monday that Trump is “using every lever of his executive authority and constitutional authority within the bounds of the immigration laws of our country to ensure that our streets are safer for law-abiding Americans.”

However, what happens next between the Trump administration and groups like the American Civil Liberties Union, which filed a lawsuit Saturday, may be determined when a hearing takes place Monday evening. Immigration advocates claim that Trump’s use of the AEA is unconstitutional.

The Department of Justice pushed to have the matter vacated, claiming that the ACLU cannot interfere with Trump’s efforts to deport migrants for national security purposes. However, the court denied the motion and said that the hearing would take place as scheduled.

Leavitt said Monday that the White House expects to win an ongoing legal fight involving the AEA. Her prediction came two days after James Boasberg, chief justice of the District Court of the U.S. District of Columbia, issued a temporary restraining order preventing deportations of the migrants for 14 days.

Trump announced he would invoke the AEA on Saturday in a proclamation issued by the White House. After previously declaring members of Tren de Aragua a foreign terrorist organization in an executive order, Trump said that the Venezuelan prison gang is conducting “irregular warfare” against the United States. By doing so, the White House placed the organization in a category that allows immigrants connected to Tren de Aragua to be apprehended, detained and deported under the AEA.

However, Jean Lantz Reisz, the co-director of the immigration clinic at the University of Southern California’s Gould School of Law, said that the activity of Tren de Aragua does not meet the criteria needed to invoke the AEA. Under the law, the AEA can only be invoked when war is declared between the U.S. and a foreign nation of government or an invasion is perpetrated, attempted or threatened.

“A cartel member, a gang member isn’t going to be a foreign government,” Reisz told CNN in a 2024 interview. “If the Trump administration … wanted to designate (a cartel) as a foreign government, that would run into problems, because there can only be one government of a nation.”

Reisz did not immediately respond to an interview request from on Monday.

Axios, citing a senior White House official, reported that the administration defied the judge’s orders to have the planes “turn around” because the aircraft carrying the migrants were already over international waters.

Leavitt told reporters Monday that the Trump administration did not defy the judge’s order given the timing of the planes departing the United States.

However, it seemed like because of the judge’s order being in place, White House officials knew a legal challenge would be coming.

“This is headed to the Supreme Court,” a senior White House official told Axios. “And we’re going to win.”

Should the Trump administration be successful in having the temporary restraining order overturned, immigration attorneys fear migrants who fall outside the category of being part of a terrorist organization could be opened up for deportation.

“There’s nothing in the law itself that would require it to be limited to undocumented individuals or individuals who have committed crimes,” Katherine Yon Ebright, counsel on the liberty and national security team at the center-left Brennan Center for Justice, told National Public Radio. “It’s not about legal status, consistent with the idea that it’s a wartime authority, not an immigration authority.”