This month, the Supreme Court ordered that Venezuelans threatened with deportation under an 18th-century wartime law be given a measure of due process — a chance to challenge their removal from the country in court.

On Thursday, a declaration by an immigration official that laid out the Trump administration’s process for complying was unsealed.

According to the official, detainees would be told of their impending removal in notices written in English and then would get one phone call and at least 12 hours to indicate that they wished to challenge their deportation. But if they did not file in court within 24 hours after giving notice, according to the declaration, they could be sent out of the country — including to a notorious terrorism prison in El Salvador.

The disclosure caused legal experts to react with astonishment and predict that judges, potentially including the Supreme Court justices, would most likely look askance.

“The administration’s notion of due process is a joke,” said Michael J. Klarman, a law professor and historian at Harvard. “I cannot imagine any non-MAGA judge taking the argument seriously.”

Mr. Klarman noted that the Supreme Court had previously defined due process requirements. In Goldberg v. Kelly, decided in 1970, the justices found that before revoking a person’s welfare benefits, the government must provide notice of the reason and a hearing where the person could present evidenceand contest the termination.