The Trump administration’s use of an obscure portion of immigration law to detain and attempt to deport pro-Palestinian activist Mahmoud Khalil is likely unconstitutional, according to an order issued Wednesday by a federal judge in New Jersey.

The former Columbia student and pro-Palestinian activist remains in detention despite a federal judge’s partial ruling in his favor.

Khalil, a Columbia student, was arrested by ICE in March over his involvement in pro-Palestine activism despite being a permanent resident. Citing a Cold War-era law, administration officials claimed Khalil’s presence in the country is detrimental to the US’s foreign policy interest.