The “zero tolerance” disciplinary rules that turned many public schools into police states beginning in the 1990s have taken an especially heavy toll on students of color, who are repeatedly singled out for the harshest treatment.

To get a feeling for what that means, watch this video of a police officer in a Columbia, S.C. high school wrenching an African-American girl from the desk where she is seated, hurling her to the floor, then dragging her across the room.

According to the local sheriff, the officer was summoned to deal with “disruptive” classroom behavior of the sort that would once have been dealt with at the principal’s office — but that now leads to body slams and handcuffs.

This video is reminiscent of one taken earlier this year showing a white police officer in McKinney, Texas throwing a bikini-clad black girl to the ground during a dispute that took place at a neighborhood swimming pool.

The South Carolina case also brings to mind a horrific event in Texas two years ago in which a sheriff’s deputy, responding to a school fight that had already ended, gratuitously Tased 17-year-old Noe Niño de Rivera. The teenager hit his head on the floor, suffered a massive brain hemorrhage and had to undergo emergency surgery. He was placed in a medically induced coma for 52 days.

The viral video from South Carolina has brought this case international exposure. But details gleaned from lawsuits and civil rights complaints suggest that this kind of brutality happens in schools all the time. This is what comes of transforming school buildings from places run by educators who are trained to handle children into quasi-jails run by police.