In the wake of the tragic massacre in Florida on Wednesday, there were copious numbers of people who reiterated their long-standing plea that armed police be stationed in schools across the nation to protect the students who attend them. One consistent objection from people opposed to such an idea goes something like this: stationing police in schools will increase the “school-to-prison pipeline.”

The ACLU states, “’Zero-tolerance’ policies criminalize minor infractions of school rules, while cops in schools lead to students being criminalized for behavior that should be handled inside the school.”

The ACLU’s position has been echoed many times over; a group called the Puente Movement, opposing an Arizona bill that would prioritize grants for school resource officers (SROs) and juvenile probation officers, wrote, “This will result in more police officers being placed in black/brown schools, which will increase the arrests of Black and Latino students on campus—feeding the school-to-prison pipeline. … A safe school cannot be defined by over-policing."

Reason magazine echoed, “The ubiquitous presence of law enforcement in public schools has led to serious infringements of students' Fourth and Fifth Amendment rights, and it has increased the likelihood that minor disputes between students will escalate into criminal justice issues. … More broadly, the increased police presence in schools is directly related to the rise of zero tolerance and the so-called school-to-prison pipeline.”

Earlier this month, in Minneapolis, Minnesota, young people marched to a Minneapolis school board member’s home to protest police officers in schools. One young person stated, “With cops in our schools, black and brown youth in the Twin Cities are overpoliced and criminalized. … The Minneapolis school board has continued to fund these violent policies. Those in power continue to ignore us.”

But a 2016 report, quoting a nationwide survey of 470 high school and middle school principals in the U.S. from 2003 through 2008 conducted by researchers at the University of Maryland, pointed out:

… schools with SROs reported more serious crimes, more minor crimes, and higher rates for student expulsions than schools without SROs (Na & Gottfredson, 2013). While the authors of this study immediately jumped to the conclusion that the presence of SROs caused normal problem student behaviors to be treated as serious crime, and to be punished more severely through arrests and expulsions, it is also just as likely that they have the order reversed. In other words, this study fails to address the likelihood that SROs tend to be assigned to schools that already have significant crime and problem student behavior issues, and less likely to be utilized in schools that do not experience as severe safety and student conduct issues.

The report cited a “more thorough and controlled study, published in 2009,” then stated:

No differences were found between the schools in the overall number of arrests per student, suggesting that SROs arrested just as frequently as schools that relied on calling patrol officers. Compared to schools without SROs, schools with SROs experienced fewer arrests for serious crimes such as assault and weapons charges, and more arrests for disorderly conduct charges. … The evidence in this study also suggest that when SROs do arrest students, they tended to downgrade the severity of the charges against the student to disorderly conduct rather than an assault or felony charge.

As the report noted, a third study by researchers at Mississippi State University found that SROs were less likely to refer juveniles to the juvenile court for misdemeanors or status offenses.

The report concluded:

Furthermore , SROs create the opportunity for school-aged children to have non-confrontational, non-enforcement contacts with law enforcement officers that may contribute to more positive opinions of the police later in life. Finally, the known presence of an SRO on campus may enhance the safety of our children, as the mass shootings at grade schools in the U.S. to date have not occurred at schools with an SRO presence. The research to date does not support the “school to prison pipeline” theory, and further research may well support the widespread belief held by principals that the use of SROs tends to have a positive impact on schools and students.