Mahmoud Khalil appeared Tuesday in a federal appeals court in Philadelphia as he continues to challenge a deportation case brought by President Donald Trump's administration over his pro-Palestinian activism at Columbia University.

The hearing before the 3rd Circuit Court of Appeals came as the government seeks to overturn a lower court order granting Khalil's June release from a Louisiana immigration jail.

Khalil's attorneys have asked the three-judge panel to affirm the district court's ruling, which prevents federal authorities from detaining him again and beginning the deportation process.

Drew Ensign, an attorney for the government, countered that the lower court judge overstepped his authority and that the case should be left to the immigration judge in Louisiana.

"All of this is being conducted in an improper forum," Ensign said. "So that should be a full stop."

An immigration judge last month ruled that Khalil could be deported, though the case is now under review by a separate appeal board.

Khalil, who is a legal U.S. resident married to an American citizen, has vowed to continue advocating for Palestinians as his case plays out. A magistrate judge recently permitted him to travel across the country for rallies and other events.

"This case is about every single person in this country, whether they're citizens or not," Khalil told supporters after the hearing. "It's about their freedom of speech and their ability to dissent and their ability to speak up, especially about Palestine and the genocide that's happening."

Khalil was the first protester arrested in the Trump administration's sprawling effort to deport student activists, academics and others who joined pro-Palestinian protests, which the government has equated with antisemitism.

Khalil has repeatedly rejected allegations of antisemitism.

Mahmoud Khalil appears in Philadelphia court as Trump administration seeks re-detainment, deportation