Government lawyers cited "exigent circumstances" during the arrest.

Government lawyers say officers with Immigration and Customs Enforcement Homeland Security Investigations (HSI) did not have a warrant for Columbia University activist Mahmoud Khalil's arrest when they took him into custody last month, according to a filing submitted in the case.

Khalil's lawyers say the admission contradicts what officers told Khalil and his lawyers at the time of his arrest and in a subsequent arrest report.

In the filing, lawyers for the Department of Homeland Security said Khalil, a green card holder and permanent legal resident, was served with a warrant once he was brought into an ICE office in New York after his arrest.

The officers "had exigent circumstances to conduct the warrantless arrest, it is the pattern and practice of DHS to fully process a respondent once in custody with an I-200 (warrant) as part of that intake processing," government lawyers wrote.

DHS claimed its officers were not required to obtain a warrant for Khalil's arrest, in part, because they had reasons to believe it was likely "he would escape before they could obtain a warrant."

In the filing, DHS attorneys said agents approached Khalil inside the foyer of his Columbia-owned apartment building and claimed that, while his wife went to retrieve his identification, Khalil told them he was going to leave the scene.

"The HSI supervisory agent believed there was a flight risk and arrest was necessary," the filing stated.

Khalil's lawyers have pushed back on the claim that he was uncooperative with authorities.

In a sworn declaration submitted in court last month, attorney Amy Greer, who was on the phone with Khalil's wife at the time of his arrest, said an agent at the scene told her they had an administrative warrant.

"I asked the basis of the warrant, and he said the U.S. Department of State revoked Mahmoud's student visa," Greer said. "When I told Agent Hernandez that Mahmoud does not have a student visa because he is a green card holder and permanent resident in the U.S., he said DHS revoked the green card, too," she wrote in the declaration.

Khalil's lawyers say the warrantless arrest is one of the reasons he should be released.

"That night, I was on the phone with Mahmoud, Noor, and even the arresting agent," Greer said in a statement. "In the face of multiple agents in plain clothes who clearly intended to abduct him, and despite the fact that those agents repeatedly failed to show us a warrant, Mahmoud remained calm and complied with their orders. Today we now know why they never showed Mahmoud that warrant - they didn't have one.

The statement went on to say: "This is clearly yet another desperate attempt by the Trump administration to justify its unlawful arrest and detention of human rights defender Mahmoud Khalil, who is now, by the government's own tacit admission, a political prisoner of the United States."

An immigration judge earlier this month ruled that Khalil, a leader of Columbia's encampment protests in the spring of 2024, could be deported on grounds that he threatens foreign policy, as alleged by the Trump administration.