As protesters streamed through Philadelphia last summer and fall, Anne Berg was often there, wearing her bright green “legal observer” hat and taking detailed notes. Volunteering with the National Lawyers Guild, Berg routinely positioned herself without fear between lines of police and protesters as a neutral third party.

But on the night of Oct. 27, at 52nd and Market Streets, Berg said she went from observer to target, when an officer lunged at her, grabbed her by the backpack, and began striking her in the legs with a baton.

To Berg, the treatment was shocking.

“The [civil affairs] police all know me. They all know who we are, what we do, and why we’re there. I have no doubt that the officers the night after Walter Wallace Jr. was murdered knew who we were also,” she said, “but that was a situation where they clearly did not care. They were beating people indiscriminately.”

Berg is one of two legal observers — the trained volunteers who take detailed notes and monitor public demonstrations for civil-rights violations — who filed a lawsuit against the city and the Police Department last week over allegations of brutality during the October protests. The other, Catherine Heite, said in the lawsuit that police “forced her to the ground causing her to strike her head, struck her with impact weapons, shields, feet, and other means.”

Heite said by email that she was standing on the sidewalk when police rushed and tackled her. “I kept telling them I was a legal observer and asking why I was being arrested. The officer kept saying ‘you’re going to need a lawyer’ and calling me ‘trash.’ When she put me in the van she said, ‘Get in there with the rest of the trash.’ "”

Paul Messing, a civil-rights lawyer representing the two along with a third plaintiff who alleged similar treatment, called the incidents ”unconscionable.” He added: “They were wearing hats that say ‘legal observer,’ or bright orange shirts that say ‘legal observer.’ ”

A spokesperson for Mayor Jim Kenney said neither the city nor the Police Department would comment because of the ongoing litigation.

Aine Fox, a member of the collective Up Against the Law, said that in years past, relations with police had been amiable. But between May and October of last year, she said, every one of the group’s 15 core legal observers was injured by police at protests. She said three suffered concussions.

“We were absolutely targeted,” Fox said. “We were collectively shot at, tear-gassed, point blank in our faces pepper-sprayed. Some of our folks had concussions from being hit with batons.”

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At one point, she said, an officer blamed the problem on the group’s black uniforms. They switched to luminous orange T-shirts. “It didn’t really seem to have any impact on whether we were tear-gassed,” Fox said.

The three plaintiffs, whose lawsuit seeks unspecified compensatory and punitive damages, join hundreds of litigants who say they showed up at protests against police brutality only to be subjected to it.

Some were on I-676 last June when police took aim with rubber bullets and tear gas. Kenney later apologized, calling the incident “completely unacceptable.” Others were in the neighborhood of 52nd Street in West Philadelphia the day before when the area was flooded with tear gas.

The city commissioned an after-action review that found insufficient preparation and inadequate use-of-force policies. Civil-rights advocates have also asked the United Nations to step in, through a letter of complaint alleging excessive force and racial discrimination.

There has been less scrutiny of what took place on two nights in October, when citizens took to the streets with outrage over the killing of Wallace, who was suffering a mental-health crisis and was holding a knife when police shot him.

Instead of tear gas, that night, many officers had their batons at the ready. An Inquirer report exposed one incident from those protests involving a child taken from his mother’s car while police allegedly smashed the SUV and beat its adult passengers.

» READ MORE: Police beat her and took her son during West Philly unrest. A month later, they’re still ‘petrified.’

Anlin Wang, who was also there to observe, said he was shocked to see police attacking Berg, a legal observer. Wang said he began filming, but an officer chased him and struck him, too, with a baton.

At the same intersection, Duncan Gromko said he was assaulted when he saw police beating a young woman and asked them to stop. Then, Gromko said, police struck him three or four times with batons, before arresting him. He said he saw at least one person taken to the hospital with injuries.

“The crazy part about it was I felt like they just jumped in and started swinging their batons. I never heard disperse,” he said.

Mary Catherine Roper of the ACLU of Pennsylvania said legal observers are usually clearly identified, and taking part in First Amendment-protected activities.

“The issue is that there shouldn’t be this level of violence toward anyone at these protests — and when it does happen to be a legal observer then there are extra questions,” Roper said. “To the extent that police were targeting legal observers, that would be a really bad thing, particularly in an era where the Police Department is claiming it wants to be more transparent and open to criticism.”