Mr. Khalil, a legal permanent resident, has been held in Louisiana for more than three months. The judge said he would be released on Friday unless the government successfully appeals.
A federal judge on Wednesday barred the Trump administration from continuing to detain Mahmoud Khalil.
However, the judge, Michael E. Farbiarz, paused his own order, saying that it would not go into effect until 9:30 a.m. on Friday, which would allow the administration to appeal.
Mr. Khalil, whose wife and infant son are American citizens, has been held in Louisiana for three months. He has not been accused of a crime.
This is a developing story and will be updated.
