A federal judge on Friday ordered the U.S. government to free former Columbia University graduate student Mahmoud Khalil from the immigration detention centre where he has been held since early March while the Trump administration sought to deport him over his role in pro-Palestinian protests.

Ruling from the bench in New Jersey, U.S. District Judge Michael Farbiarz said it would be "highly, highly unusual" for the government to continue to detain a legal U.S. resident who was unlikely to flee and hadn't been accused of any violence.

In reaching his decision, Farbiarz said Khalil is likely not a flight risk and "is not a danger to the community. Period, full stop."

He ordered Khalil released from a detention centre in rural Louisiana later Friday. The government had "clearly not met" the standards for detention, he said later in the hourlong hearing, which took place by phone.

Khalil was the first arrest under U.S. President Donald Trump's crackdown on students who joined campus protests against Israel's war in Gaza. U.S. Secretary of State Marco Rubio has said Khalil must be expelled from the country because his continued presence could harm American foreign policy.

Farbiarz had ruled earlier that the government couldn't deport Khalil on those grounds, but gave it leeway to continue pursuing a potential deportation based on allegations that he lied on his green card application. Khalil disputes the accusations that he wasn't forthcoming on the application.

Khalil's lawyers had asked that he either be freed on bail or, at the very least, moved from a Louisiana jail to New Jersey so he can be closer to his wife and newborn son, who are both U.S. citizens.

WATCH | Columbia student activist detained: 

Palestinian student activist detained by U.S. immigration agents

Mahmoud Khalil, a Columbia University student in the country legally, was arrested by U.S. immigration agents and faces possible deportation for his involvement in pro-Palestinian protests. It’s one of the first known arrests linked to the Trump administration’s threats against student activists.

Detained over participation in pro-Palestinian demonstrations

The judge noted Khalil is now clearly a public figure given his prominence during the campus protests and since his detainment.

He was detained on March 8 at his apartment building in Manhattan over his participation in pro-Palestinian demonstrations. His lawyers say the Trump administration is simply trying to crack down on free speech.

Khalil isn't accused of breaking any laws during the protests at Columbia. The international affairs graduate student served as a negotiator and spokesperson for student activists.

He wasn't among the demonstrators arrested, but his prominence in news coverage and willingness to speak publicly made him a target of critics.

The Trump administration has argued that noncitizens who participate in such demonstrations should be expelled from the country as it considers their views antisemitic.

The judge noted Khalil has no criminal record and the government has put forward no evidence to suggest he's been involved in violence or property destruction.