A spectre is haunting the United States – the spectre of tents. Apparently, they are the greatest threat to order, to education, and perhaps to capitalism, in a generation or more.

The Occupy movement encampments have caused extraordinary repression.Two weeks ago, Occupy Cal returned the movement to the UC Berkeley campus – revitalising the wave of occupations, strikes and walkouts against privatisation and austerity that had spread rapidly throughout the University of California system in 2009-2010. In two separate showdowns with police, non-violent campers joined arms and stood their ground on a grubby knoll at the margin of Sproul Plaza, iconic home to campus militancy in the United States.

The beatings that followed were immediate, unconscionable – and recorded. Some campers were thrown to the ground, dragged by their hair, hospitalised. The hurry and panic of the police insisted on a single, hysterical directive: not one tent should be raised. In response, the students called for a system-wide strike on 15 November.

Strike day at the University of California's Davis campus (where I work) ended with a 20-hour occupation of the administrative bunker. Students were allowed to remain, a rare event in the United States – but Linda Katehi, the University's chancellor, has generally been thought among the administrative classes to have a light, deft touch in these situations. The protest was largely defused, and most students left of their own accord.

But they also decided to start Occupy UCD on last Thursday, pitching 25 tents in the autumnal chill. The next morning, news came that they would not be allowed to maintain an encampment. "Health and safety risks" were cited, per the brutally ironic mantra of the powers that be. Promptly, at 3pm on Friday afternoon, riot police from three jurisdictions massed around the corner, and began shambling across the lawn clubs drawn, guns raised.

The students are not experienced fighters, by and large. But they are serious people. They huddled together in a last flurry of decision, and decided to stay. They joined arms in front of the tents, which occupied a tiny fraction of the great quad and looked less like a health and safety risk than a nice advert for a wilderness supply shop. The pro forma order to disperse was given as the students endeavored to note they weren't violating any policy whatsoever. The cops advanced as the students chanted, made some quick arrests, charging in to grab a few kids and throw them to the ground, handcuffing them with zip ties.

At this point, the growing crowd of protesters formed a very calm, even cheerful circle – facing outward – around the four dozen officers and sat down, arms linked here and there. They did not wish to see their comrades removed, and let this be known.

What followed would shortly become the lead story in the national news. Although video shows police entering and leaving the circle without difficulty, joking and turning their backs on the protesters, they decided that they were trapped and under threat. A couple officers exited the ring of students led by one Lt John Pike who, with the demeanor of a bored groundkeeper, sprayed "pepper spray" directly in the faces of some 30 students, at the range of just a few inches. When this failed to disperse everyone, he went in closer, making sure to get the eyes if he hadn't on first pass and, when possible, to spray down the throats of young people sitting down on a lawn. People cried out in horror and pain. And the police seem to retreat before the growing fury of the amassed crowd.

Pike was unleashed by the campus police chief Annette Spicuzza, who has now been placed on leave, but of course, the riot squads were summoned and set loose by Linda Katehi herself. Because of, well, the tents. She subsequently sent first one and then another email to the campus community that oscillated between contemptible and pathetic: "pepper spray was used", we learn. No mention that this mysterious passive use of pepper spray was in absolute violation of every single policy to hand, including the findings of the ACLU. Eventually, Katehi conceded that "the video is chilling to us all" – though, surely, the chill of the students sent to hospital differs from the chill of a chancellor who authored the health and safety risk herself.

Following a call by assistant professor Nathan Brown, the Davis Faculty Association has called on Chancellor Kateh to resign. Letters of support pour in from around the globe; an online petition has received more than 50,000 signatures; academic boycotts of Davis are bruited.

This may happen; when such administrated violence makes international news, heads sometimes roll. There is a move afoot as well to turn UC Davis and perhaps the wider university system into a series of sanctuary campuses, where police are not welcome. The evidence is incontrovertible: police pose a far greater risk to health and safety, let alone to free speech and civil rights, than do tents. They do not belong in our places of learning.