Trump signed the order when he returned to office for his second term. Judges around the country quickly blocked it from taking effect. “Blatantly unconstitutional” is what one of them called it.

The citizenship clause of the Constitution’s 14th Amendment, which was added after the Civil War, says, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.”

The government argued that the citizenship clause was meant to benefit newly freed slaves and their children rather than “the children of aliens who are temporarily present in the United States or of illegal aliens.” Focusing on the “subject to the jurisdiction thereof” language in the amendment, the government argued that babies born to people unlawfully or temporarily in the country aren’t “subject to the jurisdiction” of the U.S.