Donald Trump said he wants to use a 1798 law “to target and dismantle every migrant criminal network operating on American soil.”

But a second Trump administration’s mass detention and deportation efforts could face difficulty if attempted under that wartime law, known as the Alien Enemies Act or Alien Enemy Act.

The law says:

That language reflects a potential problem with the Republican presidential nominee’s proposal: It’s not tied to a declared war or an invasion or predatory incursion by another country.

Congress (not the president) has the power to declare war. And while Trump and other politicians have used invasion-type language when talking about immigration, that doesn’t turn the actions of people from other countries into actions taken by other countries. It’s a wartime law, and there isn’t a war.

That doesn’t mean the law hasn’t been abused and couldn’t be again, as this Brennan Center analysis explains regarding the statute, which Democrats have proposed repealing.

It’s a wartime law, and there isn’t a war.

Nor can we be sure what would happen if an enforcement attempt landed at a Supreme Court that has taken an expansive view of presidential power — especially if Trump and Republicans are able to further shape the court. Given the tension between Trump’s stated plan and the text of the law, his best hope in that scenario might be that the Roberts Court deems it the sort of “political question” that courts refuse to resolve (while effectively resolving the challenged action against the challenger). Even on that legal terrain, however, a Trump victory wouldn’t be guaranteed.

What’s more certain is that Trump’s recent invocation of the 18th-century law wasn’t a random musing, and (relatedly) it wasn’t the first time he has mentioned the act. So if he wins in November, we could soon find out how far the high court will let him go on this front.

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Jordan Rubin

Jordan Rubin is the Deadline: Legal Blog writer. He was a prosecutor for the New York County District Attorney’s Office in Manhattan and is the author of “Bizarro,” a book about the secret war on synthetic drugs. Before he joined BLN, he was a legal reporter for Bloomberg Law.