The events have grabbed headlines and public attention, sparking what are now all too familiar debates in the United States about police overreach. In Raleigh, North Carolina, a water-balloon fight at Enloe High School, initiated as a senior-day prank, ended with eight teens arrested and two dozen police officers dispatched to the campus “to restore order.” When a Virginia 4-year-old with ADHD threw a temper tantrum in his prekindergarten classroom late last year—allegedly throwing blocks and hitting and kicking his educators—the school’s principal, according to reports, summoned a deputy assigned to the school, who then handcuffed the child and transported in a squad car to the sheriff’s office. And in a recent episode whose news has since gone viral, a Texas, teen with a keen interest in gadgets built a clock, took it to school to show his teacher, and was sent to juvenile detention when police mistook his device for a bomb.

The details of each of these and other cases vary, but the results have largely been the same. In settings where schooling and policing intersect, the disciplining of students—often for behavior as innocuous as school-age pranks or as commonplace as temper tantrums, and in some cases including children who are so young they still have all their baby teeth—can extend beyond the purview of principals and school staff to law-enforcement who have little to do with education. Data suggests that this is a growing and, for some, disconcerting trend.

Estimates reported by The New York Times in 2009 indicated that as many as 17,000 sworn police officers were posted in U.S. schools at the time, and federal data included in a National Center of Education Statistics report offers a closer look at the characteristics of campus-based police. According to the report, a little over three in four high schools and the vast majority of large schools (those with 1,000 or more students)  have armed security staff, with only a slight statistical difference between urban and suburban areas. But there is great variation based on race and class: Schools where at least half of the children are nonwhite, as well as high-poverty schools (meaning those where at least 75 percent of students are eligible for free or reduced-price lunch) are home to the highest percentages in the country of K-12-campus law enforcement.

The origin of school-employed police—who are often officially referred to as “school resource officers” (SROs)—dates back to the 1950s. It arose as part of an effort in Flint, Michigan, to foster relationships between local police and youth. That basic idea then spread to other locales, where SROs soon took on roles ranging from counselors and coaches to tutors and mentors. But in the 1990s, the initiative’s focus underwent a dramatic policy shift, with SROs drifting from their mission as community liaisons, largely thanks to the Justice Department’s “COPS in Schools” grant program. Between 1999 and 2005, the department’s community-policing division reportedly awarded in excess of $750 million in grants to more than 3,000 law-enforcement agencies, resulting in more than 6,500 newly hired SROs. And because the recruitment and training of these officers were largely overseen by conventional police departments, board and district officials—who are typically the decision-makers when it comes to school policies—had little, if any, clout over these efforts.

The sharp increase in campus-based law enforcement coincides with the 1999 Columbine High School shootings, which left 15 dead, including two teen gunmen, and prompted calls across the country for a stronger police presence on school grounds. The Sandy Hook massacre in 2012 also incited renewed interest in such efforts, with federal funds earmarked for SROs flowing to local police departments. In Montgomery County, Maryland, a suburb adjacent to Washington, D.C., the number of SROs doubled in the year following the Connecticut mass school shooting.

“The original point of SROs was to give young people the opportunity to interact with [police] officers in a positive way, and there is some reason to think this can be accomplished in some places,” said Emily Owens, a criminology professor at the University of Pennsylvania. “But of course, having an officer means that there will be an increased likelihood that law enforcement is involved in what would otherwise be a disciplinary event.”

Combined with the rapid expansion of zero-tolerance discipline in schools that accompanied the War on Drugs, these isolated yet seminal incidents of mass violence help explain the upsurge in school resource officers, making them a fixture in many of the nation’s schools. A recent survey conducted by the Department of Education found that 43 percent of public schools employ security staff, including school resource officers, while 28 percent have “sworn law enforcement officers routinely carrying a firearm.”

While law enforcement’s presence at schools is hardly a new phenomenon, its value and purpose has lately grown especially contentious. As police officers, those engaged in school-based law-enforcement are, in a way, “beat cops” who are often called on to serve as school disciplinarian. And some experts and juvenile-justice advocates cite systemic educational risks when police patrol school hallways. A report published by the Justice Policy Institute in 2011, “Education Under Arrest: The Case Against Police in Schools,” concludes that placing SROs and other police in educational institutions exaggerates how school misbehavior, much of it involving minor infractions, is interpreted—to the extent that such activities can be treated as criminal offenses.

These tendencies result in arguably unnecessary arrests that increase the likelihood that a child will end up in the juvenile-justice system—and later, as a byproduct of these experiences, adult prisons. According to the institute’s research, youth with court records are more inclined to drop out of high school, and because schools with SROs are more likely to see students arrested for minor offenses, the presence of such officers on campus can take a significant toll on students’ academic outcomes. When UPenn’s Owens examined the data, she found that, on average, “having SROs means more young children [youth under 14-years-old] will be arrested for stuff that happens in school.”

“Students are needlessly arrested for offenses as minor as … swearing at a teacher or throwing spitballs,” said Amanda Petteruti, a senior policy analyst who authored the Justice Policy Institute paper. “SROs lead to discipline applied without the filter of school administrators or policies.”

The inclination of SROs to criminalize youth behaviors, especially that of blacks and Latinos, has become particularly concerning for social-justice activists, community leaders, and parents. In the months following the McKinney, Texas, story, an analysis by the Austin-based public-interest law center Texas Appleseed found that police officers assigned to McKinney schools had arrested and ticketed black students at an “extremely high and unequal” rate. In a district where black students account for only 13 percent of the population, they make up 39 percent of arrests by McKinney SROs, the analysis found. Additionally, misdemeanor citations in McKinney against black students for “disorderly conduct” increased from 47 percent to 61 percent between January 2012 and June 2015, while ticketing of white students dropped from 28 percent to 15 percent over the same period.

Project NIA, a nonprofit aimed at eliminating youth incarceration that has tracked the arrests of students on school property in Chicago since 2010, has found comparable data. In the latest year available, according to a report from the organization, “nearly 30 black youth [in Chicago public schools] were arrested for every one white juvenile.”  

A recurring theme in debates over school police involves concern over the officers’ reportedly poor training; in McKinney, for example, the officers receive no special training before being dispatched to schools. In some cases, questions have also been raised about the amount of funding invested in such programs. In Chicago, for instance, “school police services”—the result of an agreement between the city’s police department and the mayor-appointed school board—cost taxpayers $13 million in 2013, a period during which Chicago students were protesting school-budget cuts and a shortage of school counselors.

Meanwhile, a group of parents, students, and community members in the Bronx, alarmed at the high number of arrests and summonses issued by SROs in their schools, called for a public hearing in 2012 with the New York City Department of Education and the NYPD Safety Office. That discussion led to monthly meetings and, eventually, a training workshop for New York City school police—known in the city as “school safety agents”—at which rookie officers are tasked with reflecting on racial disparities in campus-arrest data, discussing the often hidden costs of arrests and summonses on students, and engaging in conflict resolution through role play. Since the trainings commenced in 2012, Bronx schools have seen a significant fall in arrests and summonses, according to the New York Civil Liberties Union. While the Bronx still outranks New York’s four other boroughs when it comes to the total number of arrests and summonses, the Bronx’s 2011-12 school year reports cited by the NYCLU showed 256 arrests and 796 summonses, compared to 86 arrests and 285 summonses in 2014-15.

Emma Hulse, a lead organizer for the New York City advocacy group New Settlement Parent Action Committee, calls the SRO training a “powerful model” of teamwork between local parents, the D.C.-based nonprofit Children's Defense Fund, and NYPD leadership. “While we don’t always agree, the drop in arrests and summonses is a testament to [the NYPD’s] willingness to collaborate and openness to change,” she said. Joseph Ferdinand, a community member who leads the trainings for school-safety agents, has lived in the Bronx for 15 years and stepped forward to volunteer out of concern for neighborhood youth. “What I’ve seen in the [school police officers] we trained, they are more willing to understand rather than be understood,” said Ferdinand.

Absent the elimination of police on all school campuses—which as things stand seems like an unlikely scenario—investing in police training that involves the kinds of partnerships developed in the Bronx and revamping the role of law-enforcement officers assigned to schools is gaining momentum. Also recommended are clear standards that prohibit SROs from overseeing routine discipline problems, a stance that the National Association of School Resource Officers endorses.

“When it comes to formal discipline, especially suspensions and expulsions, there’s no place for law enforcement,” Maurice “Mo” Canady, the association’s executive director recently told Teaching Tolerance. With a new school year just underway, tens of thousands of public schools still have not received Canady’s memo.