The Trump administration admitted in a court filing that it had erroneously relied on an ICE memo to justify arrests at immigration courthouses as part of an ongoing federal case brought by groups seeking to block the tactic.

Federal prosecutors said Tuesday that they had used the memo, titled “2025 ICE Guidance,” to defend the Trump administration’s deployment of ICE agents at courthouses, which led to numerous arrests of immigrants attending hearings.

The memo indicated that “ICE officers or agents may conduct civil immigration enforcement actions in or near courthouses when they have credible information” that a targeted person would be “present at a specific location.”

But, the Justice Department said in the court filing, the memo “does not and has never applied to civil immigration enforcement actions in or near” immigration courts.

The Department of Homeland Security, which oversees ICE, did not immediately respond to a request for comment.

In a filing Wednesday, the immigrant rights groups that brought the case challenging the administration’s tactics of arresting immigrants at mandated court hearings said the implications of the Justice Department’s disclosure “are far-reaching.”

In a statement, Amy Belsher, a New York Civil Liberties Union attorney for the plaintiffs, called the development a “shocking revelation.”

“It is yet again another example of ICE’s brazen disregard for the lives of immigrants in this country,” Belsher said. “It is now clearer than ever that there is no justification for ambushing and arresting people who are showing up to court.”

The government said in its filing that it became aware of the mistake Tuesday when it received an email that was sent to ICE personnel as a “reminder that the May 27, 2025, Guidance does not apply to Executive Office for Immigration Review (Immigration) courts, regardless of their location.”

Prosecutors did not say why they also received the ICE email.

Prosecutors said they informed the immigration rights groups that brought the case about the mistake.

The U.S. district judge presiding over the case, Kevin Castel, had rejected the groups’ request to block the administration’s courthouse arrests. In the ruling, Castel said ICE’s guidance “allowed arrests at or near an immigration court.”

In its filing Tuesday, the Justice Department repeatedly apologized to Castel for a “material mistaken statement of fact that the Government made to the Court and Plaintiffs” when it argued on behalf of the immigration agency.

“Based on our discussions with ICE today, this regrettable error appears to have occurred because of agency attorney error,” prosecutors wrote.

As of Wednesday night, Castel had not entered a response in the case’s public docket.

As a result of the mistake, prosecutors acknowledged, the court’s Sept. 12 opinion and order and the plaintiffs’ briefs “will need to be reconsidered and re-briefed for the Court to adjudicate Plaintiffs’ APA [Administrative Procedure Act] claims against ICE on the merits.”

Prosecutors said they received approval from ICE counsel before they filed every brief and made any oral arguments to the court and plaintiffs in the case.

Even though the government was withdrawing parts of its briefs that relied on the ICE memo, prosecutors wrote, the withdrawal “does not affect its arguments that ICE’s immigration courthouse arrests do not violate any so-called common-law privilege against courthouse arrests.”

The Trump administration’s tactic of detaining immigrants at scheduled hearings has sparked outcry. In May, Dylan Contreras, a New York City public school student with no criminal history, was detained after a routine hearing. Contreras, who was 20 at the time and pursuing a green card after having arrived from Venezuela, was released this month.

DHS said that Contreras entered the U.S. during the Biden administration and that ICE was “following the law and placing these illegal aliens in expedited removal, as they always should have been.”

His lawyers argued Contreras was seeking asylum.

New York Mayor Zohran Mamdani said on X, “What should have been a time for him to focus on finishing high school instead became ten long months of isolation, after he was taken into custody at what was supposed to be a routine immigration hearing last May.”