Portland police held at least 200 people “on suspicion of disorderly conduct” during the June 4 counter-protest. scott olson / getty images

Jeremy Ibarra wasn’t planning on suing the Portland Police Bureau.

But after the 35-year-old man was arrested during a chaotic June 2017 protest—shortly after officers corralled him and at least 200 others in a group and announced they were all being detained—he and his lawyers are prepared to hold the bureau accountable. In doing so, they could accelerate a growing legal fight to ban this type of mass detention at protests.

Ibarra went to downtown Portland’s Chapman Square on June 4 as a counter-protester, hoping to speak out against the pro-Trump rally taking place across the street at Terry Schrunk Plaza. In what’s increasingly becoming the standard for Portland protests, police showed up in head-to-toe tactical gear. According to PPB, counter-protesters threw a bottle of soda and a brick at the officers. In response, PPB formed a human lasso around some 200 protesters and announced via loudspeaker that everyone inside the circle was being detained. Officers shot paintball-style bullets filled with pepper and flash bangs at the crowd while others directed protesters to disperse, according to protester testimony. When Ibarra tried to leave the crowd, he was arrested for disorderly conduct.

Instead of taking a plea deal from the Multnomah County District Attorney, Ibarra opted for a trial by jury—an unusual path for a misdemeanor charge. The decision worked in his favor: By the end of the week-long trial, the jury sided with Ibarra and issued a not guilty verdict. But Ibarra wasn’t going to leave it at that.

Days after the ruling, Ibarra’s attorneys filed a tort claim against PPB, arguing that the entire premise of Ibarra’s arrest—being held along with hundreds of people for the actions of a select few—was unconstitutional.

“The City clearly based their mass detention not on probable cause,” the tort reads. “The overbreadth of the detention caused the illegal arrest of Mr. Ibarra.”

The police tactic in question, often called “kettling,” isn’t new. New York officers kettled protesters during the 2004 Republican National Convention, DC Metropolitan Police kettled hundreds who participated in the January 2016 Inauguration Day protests, and St. Louis police were recently accused of kettling protesters following the acquittal of an officer who fatally shot a civilian. In 2014, 70 or so people were kettled by Portland police during a protest over the non-indictment of Ferguson, Missouri, Police Officer Darren Wilson. (Included in that kettle was then-Mercury News Editor Denis C. Theriault, who was reporting on the protest.) A new wave of protests spurred by the election of Donald Trump, however, has renewed the public’s pushback on kettling tactics.

“They’re not doing anything new, there’s just new people participating in protests,” says Juan C. Chavez, Ibarra’s attorney. “We’re seeing scrutiny where there should have been for a while.”

That scrutiny is also coming from the ACLU of Oregon, who filed a class action lawsuit against PPB after the June 4 protest, specifically for the kettle-style mass detention.

“Kettling protesters without probable cause and/or individualized suspicion violates the Fourth and Fourteenth Amendments of the United States Constitution,” reads the ACLU’s complaint, filed last November, that names five people who were caught in the kettle as plaintiffs.

Chavez says these mounting lawsuits against the city and its police force will hopefully encourage the PPB to reconsider how it handles large crowds. Another thing that could help: Having more protesters like Ibarra taking their misdemeanor protest charges to court—and winning. The cost of sending county prosecutors to fight petty charges in court adds up, as does pulling officers off the clock to testify against protesters.

“So often, district attorneys file these cases because they know they won’t get sued,” says Chavez. “But they have to answer to us now. Mr. Ibarra wants to show others that they also have rights, that they can fight back.”

They can, that is, if those cases even make it as far as the district attorney’s office. In April 2017, the Mercury found that the majority of protest-related arrests in Portland since Trump’s election had been rejected by the office of Multnomah County District Attorney Rod Underhill—a signal that these arrests were more symbolic than they were lawful.

Between unnecessary arrests, the PPB’s tactical armor, and kettling, some civil rights lawyers say Portland police are increasingly using scare tactics to keep people from attending protests.

Lisa Pardini, a Portland defense attorney who’s represented protesters, calls PPB’s militarized gear “bizarrely unnecessary” and believes the look provokes some of the violent action that takes place at protests. “When you’re dressed in that battle gear, it’s hard not to [be provoked],” Pardini says.

That only adds to the slippery slope of unconstitutional allegations. If kettling qualifies as protest deterrence, then the PPB could also be accused of violating Portlanders’ First Amendment rights.

Chavez says it shouldn’t be that difficult for the PPB to follow rules upheld by Oregon and the US Constitution.

“We want this practice to stop. We want people to be able to go to a protest without getting tear-gassed and without being arrested because one person allegedly threw something,” he says. “It’s as simple as that.”