Among the executive orders issued early in his term, President Donald Trump included a directive that specifically addressed the campus protests that erupted last year due to the Israel-Gaza conflict.

This order required the revocation of student visas for individuals suspected of having affiliations with Hamas. “To the resident aliens involved in pro-jihadist demonstrations, we are issuing a warning: by 2025, we will find you, and we will deport you,” the order stated.

On Saturday evening, U.S. Immigration and Customs Enforcement (ICE) acted on Trump’s warning by taking Mahmoud Khalil, a Palestinian student activist affiliated with Columbia University, into custody. Columbia was a central hub for pro-Palestinian protests last year, which sparked a national discussion about the ongoing conflict in the Middle East. Khalil was instrumental in mediating between the protesters and the university’s administration last spring, and he completed his master’s degree at Columbia in December.

“This is just the beginning of many arrests to follow,” Trump announced on Monday, claiming personal responsibility for Khalil’s detention. “We will locate, apprehend, and remove these so-called terrorist sympathizers from our country—never to return.”

Khalil’s case quickly gained international scrutiny, not only for the circumstances surrounding his detention but also because he holds a green card that allows him to live and work permanently in the United States, as noted by his attorney, Amy Greer.

A habeas corpus petition was submitted on Khalil’s behalf, challenging the legality of his arrest and subsequent detention. On Monday evening, a judge from the Southern District of New York granted Khalil a temporary stay, ruling that he “shall not be removed from the United States unless and until ordered by the Court.”

Khalil’s wife, who is eight months pregnant, is a U.S. citizen and has reportedly faced threats of arrest as well, according to Greer. Currently, Khalil is being detained at the Central Louisiana ICE Processing Center in Jena, Louisiana, according to ICE records.

His arrest occurred shortly after Trump announced plans to cut $400 million in federal funding to Columbia University, accusing the institution of not adequately addressing antisemitism on campus. Critics assert that this move seeks to stifle political expression that opposes U.S. foreign policy.

In a statement, Homeland Security spokesperson Tricia McLaughlin claimed, “Khalil engaged in activities associated with Hamas, a recognized terrorist organization,” linking his detention to Trump’s executive order. Later, Secretary of State Marco Rubio confirmed on social media that the Trump Administration “will revoke the visas and/or green cards of Hamas supporters in America to facilitate their deportation.”

A petition for Khalil’s release has garnered over 1.3 million signatures and support. Protests are also planned in New York City on Monday to demand his freedom.

Below is a summary of Khalil’s situation, along with an examination of how his green card status may signal a shift in U.S. immigration policy under Trump:

Can a green card holder face deportation?

Green card holders enjoy many of the same rights as U.S. citizens; however, they can still be subject to deportation in certain situations, typically involving criminal conduct or violations of immigration law, according to Stephen Yale-Loehr, a former immigration law professor at Cornell Law School.

Foreign nationals may face visa revocation if they are found to endorse or be connected with terrorist organizations, but the government must substantiate such claims with adequate evidence.

Greer contends that there is no evidence suggesting that her client has committed any crime or violated the terms of his residency, indicating that the Trump administration may be targeting him due to his political activism and vocal criticism of Israeli policies. Immigration law experts warn that deporting a green card holder solely based on political beliefs could violate First Amendment rights, which safeguard free speech and the right to protest.

Yale-Loehr referenced the Ragbir v. Homan case, a 2018 Second Circuit Court of Appeals ruling that determined a non-citizen with a final removal order could not be deported solely for retaliatory reasons related to their free speech.

The process for revoking a green card is rare and generally requires a hearing before an immigration judge. This process can be lengthy, necessitating clear evidence of wrongdoing, and due to significant backlogs in immigration courts, it may take years for Khalil to receive a hearing.

Should Khalil’s green card be eventually revoked due to his activism, immigration experts suggest it would represent a concerning shift in how the U.S. government interprets its authority over lawful permanent residents.

The burden of proof in deportation cases

In deportation proceedings, the government bears the burden of proof to demonstrate that the individual has violated U.S. immigration laws. This usually involves showcasing criminal convictions or other substantial legal infractions. In Khalil’s case, the government would need to prove that his actions extend beyond protected political expression and that his affiliations or activities represent a credible national security threat. His legal team maintains that there are no legitimate grounds for revoking his green card or detaining him.

“The authorities must show that he has done more than simply express his opinions, such as providing material support to Hamas,” Yale-Loehr explains. “That would justify deportation.”

“They cannot deport someone merely for advocating free speech,” he adds. “However, if they could prove he provided material assistance to Hamas, like donating to their efforts, that would certainly raise alarms.”

At this point, how the Trump administration plans to substantiate the revocation of Khalil’s green card and the ensuing deportation remains uncertain.

Tom Homan, the Trump Administration’s immigration chief, stated on Fox Business on Monday that federal authorities “absolutely can” deport individuals residing legally in the country: “Did he violate the conditions of his visa? Did he breach the conditions of his residency here by committing crimes, attacking Israeli students, locking down buildings, or destroying property? Yes, any resident alien who commits a crime is eligible for deportation,” Homan asserted.