Numerous studies have suggested an association  between exclusionary discipline  practices and an array of serious educational, economic and social problems, including school avoidance and diminished educational engagement; decreased academic achievement; increased behavior problems; increased likelihood of dropping out; substance abuse; and involvement with juvenile justice systems. All of these problems are costly to the victims and to our society. They drive up the public costs associated with the aftermath of violence, substance abuse counseling, unemployment or underemployment, policing and the justice system, and much, much more.

Indeed, school exclusion, without these supports, can exacerbate a bad situation. In the Parkland case, the fact that Nikolas Cruz had been expelled from school may have contributed to driving an angry young man who felt isolated to take out his frustration and anger by killing students and staff at his former school. In theory, zero-tolerance policies deter students from violent or illegal behavior because the punishment for such a violation is harsh and certain. However, research shows that such policies ultimately increase illegal behavior and have negative effects on student academic achievement, attainment, welfare, and school culture.