The principal’s action was the result of a new state law that had gone into effect just months earlier, heightening penalties for students who make threats at school. Passed after a former student shot and killed six people at The Covenant School in Nashville, the law requires students to be expelled for at least a year if they threaten mass violence on school property, making it a zero-tolerance offense.

Tennessee lawmakers claimed that ramping up punishments for threats would help prevent serious acts of violence. “What we’re really doing is sending a message that says ‘Hey, this is not a joke, this is not a joking matter, so don’t do this,’” state Sen. Jon Lundberg, a co-sponsor of the legislation, told a Chattanooga news station a week and a half after the law went into effect.

Tennessee school officials have used the law to expel students for mildly disruptive behavior, according to advocates and lawyers across the state who spoke with ProPublica. (In Tennessee and a number of other states, expulsions aren’t necessarily permanent.) Some students have been expelled even when officials themselves determined that the threat was not credible. Lawmakers did put a new fix in place in May that limits expulsions to students who make “valid” threats of mass violence. But that still leaves it up to administrators to determine which threats are valid.

In some cases last school year, administrators handed off the responsibility of dealing with minor incidents to law enforcement. As a result, the type of misbehavior that would normally result in a scolding or brief suspension has led to children being not just expelled but also arrested, charged and placed in juvenile detention, according to juvenile defense lawyers and a recent lawsuit.