A federal judge in New Hampshire on Monday paused enforcement of President Donald Trump’s executive order limiting birthright citizenship while the court considers a lawsuit filed by civil rights advocates in Maine and other states.

U.S. District Court Judge Joseph Laplante announced his decision following oral arguments Monday morning. The American Civil Liberties Union of Maine is a plaintiff in the case, which was filed last month by a coalition of civil rights organizations and advocacy groups and argues that the Constitution clearly grants citizenship to babies born in the United States, whether their parents are citizens or not.

Trump’s order argues that babies of noncitizens should not have an automatic right to citizenship.

Laplante said he was not convinced by the arguments presented Monday by Drew Ensign, an attorney for the U.S. Justice Department, that Trump’s order does not violate the Constitution and should be allowed to take effect. He said he was barring Trump’s order from being enforced until a final decision is issued in the case.

“I think the plaintiff has made the required showing to get a preliminary injunction — of likelihood of success on the merits, irreparable harm and the last two factors … equities and the public interest,” Laplante said.

Laplante’s order comes as judges hearing similar lawsuits in two other jurisdictions have also moved to block Trump’s order. Judges in Seattle and Maryland issued decisions last week, The Associated Press reported.

“Today’s ruling is the latest rebuke of President Trump’s wildly unconstitutional bid to end birthright citizenship,” Cody Wofsy, deputy director of the national ACLU’s Immigrants’ Rights Project, said in a written statement after the hearing. “This attempt to deny babies their citizenship is as illegal as it is inhumane, and we will keep fighting until we stop this order for good.”

Trump’s executive order, issued Jan. 20, challenges the longstanding principle laid out in the 14th Amendment of the Constitution that anyone born in the United States is a citizen, regardless of their parents’ citizenship status.

The president’s order relies on a new interpretation of the Constitution and says that citizenship is not automatic if a child’s mother is not lawfully present or is lawfully present but on a temporary basis, and the father is not a citizen or lawful permanent resident.

During oral arguments Monday, Wofsy said the executive order “is a fundamental attack on the Constitution and on the bedrock American value of birthright citizenship.”

“If the order were to go into effect, the harms would be immediate, constitutional injuries — the threat of arrest and potentially deportation, and the fear that goes along with that,” he said.

He also cited U.S. Supreme Court precedent in the 1898 case of Wong Kim Ark, who was born in the United States to Chinese parents and was denied reentry into the country after a trip abroad. In a landmark decision, the court ruled that Wong was a citizen and established legal precedent for interpreting the citizenship clause of the 14th Amendment.

“Most of the arguments in the government’s brief were, as we squarely pointed out, made and rejected in Wong Kim Ark,” Wofsy said.

Ensign, representing the U.S. government, pointed out that Native Americans are granted citizenship through federal law rather than through the Constitution, citing a different U.S. Supreme Court finding that Native Americans born on reservations do not acquire citizenship at birth. The Indian Citizenship Act of 1924, approved by Congress, gives citizenship to Native Americans born within the U.S.

“If allegiance to a tribe is insufficient … then being a citizen of a foreign power, which is to say an even more distant power, without any permanent ties to the United States, is necessarily insufficient, too,” Ensign said.

He said the United States could suffer harm if it were forced to recognize someone as a citizen. “Recognition of citizens is a core sovereign power of any state,” Ensign said.

A tricky question

Laplante asked both sides if babies would be granted citizenship retroactively if Trump’s order was allowed to take effect and then was later struck down in the courts.

Ensign said that was a tricky question, because the administration has not yet implemented the executive order and the judge’s ruling in Washington state has prevented them from taking any steps toward doing so. “As to the nuts and bolts of how it would operate, it’s a little unclear because the executive branch isn’t allowed to develop answers to those questions,” he said.

Wofsy said birthright citizenship isn’t tied to a particular document, but is based on having been born in the United States, and if the order takes effect, children born under it will still have birth certificates saying they were born in the country.

However, he said, those children could suffer severe consequences including arrest, detention and deportation if the order were to take effect, even if it was later reversed. “I think there is a very real practical problem even though legally they are and always will have been citizens under the Constitution,” he said.

Maine state government is involved in a separate lawsuit brought by Attorney General Aaron Frey and other attorneys general challenging Trump’s order in Massachusetts court. A federal judge in Boston heard arguments in that case Friday and has yet to issue a decision on an injunction.