Hundreds of people have rallied outside a New York City courtroom to demand the release of Palestinian activist Mahmoud Khalil, whose arrest over the weekend sparked condemnation and fears of a crackdown on free speech in the United States.

The demonstrators gathered on Wednesday outside Manhattan’s federal court for the first formal hearing in Khalil’s case, as he faces possible deportation for his activism.

“Release Mahmoud Khalil now!” they chanted.

During the brief hearing, Khalil’s lawyer Ramzi Kassem said his client had been allowed just one call with his legal team from the detention centre where he is being held in the southern state of Louisiana.

But Kassem said that the call was cut off prematurely and was on a line recorded and monitored by the government.

US District Judge Jesse Furman ruled that Khalil and his lawyers should have one phone call on Wednesday and another on Thursday, covered by attorney-client privilege, meaning the government would not have access to their conversation.

Furman on Monday temporarily blocked Khalil’s deportation.

Immigration and Customs Enforcement (ICE) agents arrested Khalil, a 29-year-old Columbia University graduate and US permanent resident, at his residence in New York City at the weekend.

ICE officials said they planned to revoke his green card at the behest of the US Department of State.

Khalil had been at the forefront of pro-Palestinian demonstrations at Columbia University last year, which saw students demanding an end to Israel’s war in the Gaza Strip. He largely served as a spokesperson and negotiator.

But as he campaigned for a second term in the White House, US President Donald Trump pledged to stop the pro-Palestinian demonstrations that erupted after Israel launched a deadly war on Gaza in October 2023 and deport any foreign students involved.

Upon taking office, he began to issue executive actions signalling he would carry out his threats.

“To all the resident aliens who joined in the pro-jihadist protests, we put you on notice: come 2025, we will find you, and we will deport you,” Trump said in a White House fact sheet.

“I will also quickly cancel the student visas of all Hamas sympathizers on college campuses, which have been infested with radicalism like never before.”

Trump recently welcomed Khalil’s arrest, saying on Monday that it was “the first of many to come”.

He accused students across the country of being engaged in “pro-terrorist, anti-Semitic, anti-American activity” that his administration “will not tolerate”.

But experts say Khalil’s detention highlights a widening attack on pro-Palestinian activism in the US, as well as a worrying sign for freedom of expression and dissent under the Trump administration.

“Objectively, what is really happening is an effort to silence all public expression of support for Palestinian human rights to placate right-wing supporters of Israel within the Republican Party,” Nader Hashemi, a professor at Georgetown University, told Al Jazeera this week.

Legal questions

The legal basis for Khalil’s detention also has been called into question.

White House Press Secretary Karoline Leavitt told reporters on Tuesday that Secretary of State Marco Rubio could revoke Khalil’s green card if Rubio determined his presence in the US runs contrary to the country’s national security and foreign policy interests.

Citing a government document detailing the civil charges Khalil faces, The Washington Post also reported on Wednesday that Rubio’s determination “is so far the Trump administration’s sole justification” for trying to deport him.

Separately, Rubio told reporters that Khalil’s case “is not about free speech”.

“This is about people that don’t have a right to be in the United States to begin with,” the top US diplomat told reporters at Ireland’s Shannon Airport during a refuelling stop after a trip to Saudi Arabia.

“No one has a right to a student visa. No one has a right to a green card, by the way,” Rubio said.

But speaking outside the Manhattan court, Khalil’s lawyer Kassem told reporters that the rarely used legal provision that the Trump administration seems to be invoking was not meant to silence dissent.

“It is not intended to be used to silence pro-Palestinian speech or any other speech that the government doesn’t like,” Kassem said.

Khalil’s lawyers also asked Furman — the judge overseeing the case — to order that their client be returned from Louisiana to New York.

Reporting from New York on Wednesday afternoon, Al Jazeera’s Kristen Saloomey said Khalil’s legal team argued that he should be returned to the city because he is far from his lawyers and pregnant wife.

“And they also allege that he is being targeted simply because of his activism in support of Palestinian rights and calling for an end to genocide in Gaza,” Saloomey said.

At the hearing, government lawyer Brandon Waterman said they planned to challenge Furman’s authority to decide the case.

Waterman said Khalil’s petition should have been filed in Louisiana or in New Jersey, where he was initially brought after his arrest.

Furman, calling the legal issues “important and weighty”, asked the two sides to submit a joint letter on Friday describing when they propose to submit written arguments over the legal issues raised by Khalil’s detention.