Lawyers seek release of Columbia graduate Mahmoud Khalil, arguing that his arrest was illegal. He was back in court.

There was one notable –and loudly noted – absence on Wednesday at Columbia University's graduation ceremony: detained pro-Palestinian student protest

The head of Columbia University alluded to the detention of Palestinian activist Mahmoud Khalil during a commencement speech Wednesday that drew loud boos and chants of “free Palestine” from graduating students.