The Trump administration's use of an obscure portion of immigration law to detain and attempt to deportpro-Palestinian activist Mahmoud Khalilis likely unconstitutional, according to an order issued Wednesday by a federal judge in New Jersey. Khalil, a recent Columbia University graduate and permanent US resident, is "likely to win on the merits" of his arguments against the federal government's assertion that he poses a threat to the administration's foreign policy goal of combatting antisemitism, the lengthy order by Judge Michael Farbiarz of the Federal District Court in New Jersey finds. The administration's use of that law appears to be "unconstitutionally vague as applied" to Khalil, Farbiarz writes. But the judge did not order Khalil's release, finding also that he has not provided sufficient evidence against the administration's other claims thatfailed to discloseties with certain organizations when he applied for residency status in the US. Khalil has been in detention since his arrest near Columbia in March. He was among the first in a series of high-profile arrests made by the Trump administration in the name of battling antisemitism, but which has sparked a litany of free-speech concerns. An immigration judge in April ruled Khalilcould be deportedafter the government argued his presence posed "potentially serious foreign policy consequences." Khalil's attorneys argue the government's evidence is insufficient and based solely on a letter fromSecretary of State Marco Rubiothat does not allege criminal activity. They contend Khalil is being targeted for his political speech, a First Amendment violation. The federal judge's new order is sympathetic to that argument. "The Secretary did not affirmatively determine that the (Khalil's) alleged conduct has impacted U.S. relations with other countries. Indeed, the Secretary's determination says nothing about any country other than America," Farbiarz writes. The judge also notes that deporting Khalil on those grounds would be "unprecedented." Khalil's legal team praised the order and said it will provide the additional information requested by the judge as quickly as possible to "return (Khalil) to his wife and newborn son." "The district court held what we already knew: Secretary Rubio's weaponization of immigration law to punish Mahmoud and others like him is likely unconstitutional," the legal team said, according to a statementposted by the ACLU, which is helping represent him. Khalil's case is playing out separately in immigration court in Louisiana where he's been in detention. In alengthy hearing last week, a judge denied a request to terminate Palestinian activist Mahmoud Khalil's deportation proceedings after his attorneys argued that he was arrested illegally and without a warrant over two months ago. CNN's Ruben Correa contributed to this report. For more CNN news and newsletters create an account atCNN.com