The arrest of a high school principal is triggering a dispute between principals and police-appointed security officers on the issue of who has authority over school discipline.

The principal, Mark Federman, was arrested Tuesday after protesting the treatment of one of his students. School safety agents arrested the student after she resisted an attempt to prevent her from entering her school before the official start time, allegedly punching an agent.

Mr. Federman interfered, in an attempt to prevent the student from being made a spectacle of, the president of the city principals’ union, Ernest Logan, said yesterday. The school safety agents were about to escort her through the front door in front of a crowd of students. After a scuffle, Mr. Federman and the two safety agents were treated for minor injuries at a hospital.

The executive director of the New York Civil Liberties Union, Donna Lieberman, defended Mr. Federman, saying he was “trying to protect a student,” and Mr. Logan said the incident echoed concerns of principals across the city who are clashing with safety agents.

“These are schools; these are not prisons,” Mr. Logan said. “We need to move away from the criminalization of young people in this city.”

The union that represents school safety officers, Teamsters Local 237, quickly fired back. “Safety agents have been wrongfully accused of criminalizing the schools, but they are the ones being treated like criminals,” the union’s president, Greg Floyd, said, holding up a picture of a tuft of hair he said the student had ripped from one safety officer’s head.

A resolution could come later this month. Mr. Logan said he has scheduled a meeting with safety agents, resurrecting conversations that he said have been dormant for the last several years.