Another video from different angle of #AssaultAtSpringValleyHigh in South Carolina by officer of a peaceful student: pic.twitter.com/EOp3wnjoJ1 — Niraj Warikoo (@nwarikoo) October 27, 2015

When a South Carolina police officer brutally arrested a black student at Spring Valley High School, much of the debate focused on one question: Why was a police officer called into the classroom in the first place?

The answer goes back to a misdemeanor offense for "disturbing schools." If that seems like an incredibly vague description of a crime, it's because it's an incredibly vague law: Students can be charged for "acting in an obnoxious manner" in a school. It carries a hefty punishment: a fine of up to $1,000 or jail time up to 90 days.

It's under this statute that the student in Spring Valley High School was charged for refusing to put away her phone and leave the classroom per her teacher's request.

South Carolina isn't the only state to have this kind of law. Over the past few decades, as lawmakers passed tough-on-crime policies, the idea of a tough approach trickled down to schools across the nation. As a result, schools began to outsource more and more discipline to law enforcement. School disturbance laws reflect that: Whereas a teacher would have had to find a way to deal with a disturbance before, he or she can now call on police to do the job. And seven other states, besides South Carolina, have similar laws, according to BuzzFeed's Claudia Koerner.

But as calls for criminal justice reform and instances of excessive police use of force get more and more attention in the news, these laws and the system they created — widely derided as the "school-to-prison pipeline" for how it pushes students out of schools and into the justice system — have faced higher levels of scrutiny. And the latest case in Spring Valley High School exemplifies many of critics' fears, from racial disparities in how school discipline is doled out to the unnecessary escalation the laws cause.

The school disturbance law is a major reason for juvenile arrests

Over the past few years, disturbing schools has been the third most common offense associated with juvenile cases sent to the solicitor, according to data from the South Carolina Department of Juvenile Justice. In fiscal years 2013 and 2014, about 1,189 kids were processed through the department for disturbing schools, which made up about 7 percent of all 16,754 cases.

Again, these are arrests that likely would not have existed before the law. Instead of sending kids to the juvenile justice system, schools would have likely handled most of these situations with their own in-school discipline, like detention or suspension. Or perhaps the schools would have seen the students' behavior in these cases as part of a mental health problem, and refer them to get medical help. But through these laws, states and schools have created a pipeline from the classroom to a juvenile detention center.

"If we have a child that's not following the rules, deputies are getting called in to handle that. And that's really not our role in the school."

Even police have questioned the merits of laws that create a school-to-prison pipeline. In South Carolina, Richard County Sheriff Leon Lott questioned whether the deputy who brutally arrested the Spring Valley High School student should have been called into the classroom at all: "I think that's one of the problems that we've got. If we have a child that's not following the rules, deputies are getting called in to handle that. And that's really not our role in the school. And I think sometimes the teachers and administrators should be handling things like this."

The research shows that schools that adopt tougher measures — also known as "zero-tolerance policies" — tend to rely much more on the criminal justice system. After controlling for poverty, a report from the Justice Policy Institute found schools with school resource officers — essentially, dedicated cops at schools — have nearly five times the rate of arrests for disorderly conduct as schools without school resource officers, even though the prevalence of school resource officers in schools has little relationship to reported crime rates.

What's worse, the adoption of zero-tolerance policies like the school disturbing law seems to be racially skewed. One study published in Sociology of Education analyzed a data set of more than 60,000 schools in more than 6,000 districts. It found schools with relatively larger minority and poor populations are more likely to implement criminalized disciplinary policies — such as suspensions, expulsions, police referrals, and arrests — and less likely to medicalize students by, for instance, connecting them to psychological or behavioral care.

Or, as study author David Ramey told the Daily Beast's Abby Haglage, "White kids tend to get viewed as having ADHD, or having some sort of behavioral problem. Black kids are viewed as being unruly and unwilling to learn."

Vague laws can lead to racial discrimination

No-tolerance policies and laws tend to be very vague. For example, South Carolina's "disturbing school" statute allows teachers to call in cops when a student is being merely obnoxious — an incredibly subjective standard. That leaves a lot of room for teachers, school administrators, and police to decide how the law is enforced.

The huge room for interpretation creates an enormous problem when compounded with what we know about the many subconscious biases people hold against minority groups.

As part of a study published in the Journal of Personality and Social Psychology in 2014, researchers interviewed 264 mostly white, female college students and found that they tended to perceive black children ages 10 and older as "significantly less innocent" than their white counterparts.

"Black boys can be seen as responsible for their actions at an age when white boys still benefit from the assumption that children are essentially innocent"

"Children in most societies are considered to be in a distinct group with characteristics such as innocence and the need for protection," Phillip Goff, a UCLA researcher and author of the study, said in a statement. "Our research found that black boys can be seen as responsible for their actions at an age when white boys still benefit from the assumption that children are essentially innocent."

So school staffers likely view a white student as more innocent than a black student — and therefore may be more likely to call the police on the black student than his white counterpart, even if both engage in the same unruly behavior. And this seems to happen in the real world: As the New York Times's Brent Staples reported, federal investigations have found that schools are more likely to punish black students than white students even when they take part in identical behavior.

The result: Black students are much more likely to face discipline than their white peers — and that disparity is even larger when comparing black girls and white girls.

The data, taken from a report from the Center for Intersectionality and Social Policy Studies, shows that black boys still face the highest rates of school discipline. But the report argues that "these data reveal that in some cases, race may be a more significant factor for females than it is for males."

So it's not just that the school-to-prison pipeline enables more arrests, but it enables arrests in a way that are racially skewed. These laws, then, are just another way that America's justice system appears unjust and even racist.

Watch: Why it's important to film the police