A federal judge ordered the Trump administration on Friday to release Rumeysa Ozturk, a Tufts University student, saying that her continued detention could potentially chill “the speech of the millions and millions of individuals in this country who are not citizens.”

At a hearing at the Federal District Court in Vermont, the judge, William K. Sessions III, said Ms. Ozturk should be freed immediately: “Her continued detention cannot stand.”

Ms. Ozturk, a doctoral student from Turkey, has been in detention since March 25, when Immigration and Customs Enforcement agents in masks and plainclothes surrounded her outside her home in Somerville, Mass., while she was on the phone with her mother. She was put on a plane to a detention center in Louisiana, and her friends, family and lawyers didn’t know where she was for 24 hours, they said.

Her arrest led to public outrage at her treatment and criticism that the government is abusing the immigration system to deport international students. In seeking her release, her lawyers have accused the government of detaining her in retaliation for speech that is protected by the First Amendment. The main evidence against her appears to be an essay critical of Israel that she helped to write in a Tufts student newspaper last year.

They also said the conditions at the detention center were exacerbating her chronic asthma and preventing her from carrying out her academic work.

Her lawyer, Mahsa Khanbabai, said she was “relieved and ecstatic” that Ms. Ozturk had been released.