Ninety-nine people arrested during Occupy Wall Street's 17 September anniversary actions had their court dates last week. They trooped into the courthouse accompanied by green-hatted legal observers and National Lawyers Guild representatives, and faced the judge. Their charges mostly boiled down to "being part of a public protest".

Molly Crabapple – artist, journalist, and illustrator – was one of those arrested that day. "I was plucked off the sidewalk during a protest on the anniversary of Occupy, and didn't know what I was accused of until after 11 hours in jail," she explains. "I was let off with an adjournment in contemplation of dismissal (ACD), which means that if I'm not arrested for six months, my charges will be dismissed." ACDs were given to 52 others, according to Ben Meyers of the National Lawyers Guild. Four had their prosecutions declined and one was dismissed outright; for 25 of them, prosecution wasn't ready and five weren't present. Eleven pleaded not guilty and will go to trial.

Many of those same people arrested for marches and direct actions on that day have also been involved in running Occupy's Superstorm Sandy relief efforts – work that has earned them praise from mayoral hopeful and public advocate Bill DeBlasio, and even, grudgingly, billionaire mayor Mike Bloomberg. The NYPD has yet to come out and officially thank Occupy Sandy for saving lives after the storm. But the news this week, as Occupiers had their day in court, was that in Red Hook at least, the police appreciated the efforts of Occupy Sandy volunteers in helping keep the neighbourhood safe while the power was out.

The New York Post, of all tabloids, reported that a "police source" said: "This crisis allowed us all to remove the politics and differences we had to do our job, and come to the aid of the people. We all rose to the occasion." Kirby Desmaris, an Occupy Sandy organiser, told the Post she'd had the experience of working alongside NYPD, the National Guard and the mayor's office.

In some ways, it's come full circle: during the early days of Occupy, the protesters would chant "Cops are the 99%!" and exhort officers to join them. "We're fighting for your pensions, too!" they'd say. "Goldman Sachs isn't on your side!" It was weeks of sustained police repression, kettling and pepper spray and mass arrests, that hardened lots of Occupiers into their "fuck the police" stand (and made them ally with the burgeoning "stop stop-and-frisk" movement springing from New York's communities of colour, who have long known that the police are not on their side).

Occupy Wall Street was, of course, a response to financial disaster, to the inequality that crept up on many of us slowly over the course of the past 30 years and then blew wide open with the financial crash of 2008. Zuccotti Park was always a place where those in need could get a hot meal and a place to sleep, where comfort and security working groups did their best to make sure everyone was safe and warm. The encampments were performative, sure, but they were also practical – they created a grey-water system for cleaning dishwater and keeping the kitchen sanitary, a medical tent with trained nurses and MDs providing care for residents.

All that was destroyed by the NYPD on 17 November 2011, along with 5,500 books in the library, tents, laptops, and people's homes. It should not be forgotten that Occupy Wall Street and other protest camps around the country did not fade away, but were repressed. "Arrests for protesters are aversion therapy, designed to keep you, and your friends, from wanting to protest again," says Crabapple.

Those same skills that the NYPD did its best to stamp out not only helped "prevent crime" in those same overpoliced neighbourhoods. They saved lives. Volunteers continue to work as the Red Cross delivers trash bags of hamburgers and pats itself on the back, and Bloomberg appoints a Goldman Sachs executive to oversee recovery.

It'd be too much to ask that the NYPD learn from its experiences in Red Hook – that gratuitous arrests and stopping-and-frisking don't keep people safe as well as caring for their basic needs. But perhaps when the inevitable protests start again, some of those officers will remember who was there on the ground.