I’ve just returned home from a trip to downtown for tonight’s march in solidarity with the students of Montreal, and I want to say a couple of things.

For background, it was a march of about three hundred people, give or take. Ebullient, given today’s events to the north, but not raucous. We started at Union Square, meandered around for about an hour and a half, and ended where we began. Pretty standard stuff.

I arrived at Union Square about 8:30, and headed south looking for the march. Within a couple of blocks I caught it circling back toward me, and joined up. Folks were walking on the sidewalks and in the streets, without incident — on the side streets we were mostly facing traffic, and parting when lights turned green. On the avenues we generally hugged the parked cars, taking part of a lane when there was traffic, more when there wasn’t.

Cops occasionally herded us back onto the sidewalks, and we uniformly complied when they did. (I never saw a person refuse to leave the street all night long.) But then when the cops moved on, the people did too, and folks wound up in the streets again.

It was probably something like 8:45 when I saw a white-shirted cop, a supervisor, point at a small group of people in the street a ways ahead, pretty much on their own, and say, “let’s get those kids.” He and a couple of other cops broke into a trot, quietly closing the distance. I yelled to the group to watch out, as did several other people, but we were too far back for them to hear, and so a couple of them got grabbed. When a woman got upset with the cops for busting her friends, she was grabbed too.

I want to be clear: The people I saw arrested weren’t blocking traffic. They weren’t disrupting anything. They weren’t refusing to comply with police orders. They’d just wandered onto an uncrowded street like tens of thousands of New Yorkers do every day. (A little while later, a cop stopped a few of us from crossing an empty crosswalk on a red. He actually said “don’t you see the red light?,” a phrase which, since I’m from here, left me giggling in his face.)

Folks who go to Occupy marches know all about these kinds of arrests. They’re commonplace at this point. But folks who don’t do the Occupy thing — New Yorkers who would never think twice about jaywalking in front of a cop, who’d never even notice that they were doing so — are missing something weird and unsettling in the life of the city.

I said earlier that the mood of the march was ebullient, but after every arrest, every small, unnecessary act of police violence, things turned uglier and angrier. At one point, on St. Marks Place, cops were being rough with a guy on the ground, and a bunch of us were taping to make sure that there was a record. A cop with a steroid body suddenly flew out of the group around the guy and started grabbing people, shoving them, telling them to keep walking. (None of us were blocking the sidewalk or interfering with the cops in any way.) The cop kept on that way for half a block at least, just putting his hands on whichever protesters were in arms’ reach, including people who had no idea what he wanted from them. He was clearly wound up, and physically aggressive in a completely unprovoked way, but he wasn’t out of control — he was a guy who wanted to do some shoving, and he knew for sure that he could do it without consequences.

And something occurred to me as he was doing it. Here’s someone walking down a New York City street, just assaulting people. Just pushing and shoving and yelling. He knocked one guy’s phone out of his hands, and almost sent a woman sprawling. And this miscreant was surrounded by cops. And they did nothing. Didn’t intervene, didn’t stop him, didn’t try to calm him down. They just let their guy go ahead and blithely break the law right in front of them.

If you want to know why people get in cops’ faces on these marches, this is why. If you want to know why people get amped up, this is why. If you want to know why folks chant “fuck the police,” this is why.