WASHINGTON >> The Trump administration must give lawyers with the American Civil Liberties Union 72 hours notice before transferring a U.S. citizen imprisoned in Iraq as an enemy combatant for more than four months, a federal judge has ruled.

The man, whose name has not been made public, was captured by a Syrian militia in September and turned over to U.S. forces as a suspected Islamic State fighter, raising a dilemma about what to do with him. He is said to have been born in the United States to visiting Saudi parents, making him an American citizen, but raised in Saudi Arabia, where he apparently also is a citizen.

After law enforcement officials concluded that they had insufficient courtroom-admissible evidence to bring criminal charges against the man, Trump administration officials in December decided to try to transfer him to Saudi custody, according to officials familiar with internal deliberations.

But the ruling Tuesday by the judge, Tanya Chutkan of the U.S. District Court for the District of Columbia, ensures that if such a diplomatic deal is reached, the man could fight his transfer in court.

“Absent a showing that the government — for international relations reasons or otherwise — needs to transfer petitioner now, the court does not find that the government’s interests outweigh the petitioner’s right to challenge his detention without fear of his transfer to another country,” she wrote.

The Justice Department had argued that there was no legal basis for inhibiting the government’s ability to release the detainee from U.S. custody by transferring him to the custody of another country, should a diplomatic deal be reached. The government has not publicly confirmed that it is talking to Saudi Arabia, specifically, about a transfer.

A Justice Department official said the Trump administration had not yet decided whether to appeal.

The ACLU had asked the judge to block the government from transferring the man until that litigation was complete. While her order stopped short of such a ban, Jonathan Hafetz, an ACLU attorney representing the man, praised it.

“The U.S. can’t lawlessly hand over Americans to other countries,” he said in a statement. “This ruling helps to ensure that this citizen’s rights are respected and that he will receive due process in an American court.”