The NYPD's use of a sound cannon against nonviolent protesters can indeed be considered excessive force, a federal appeals panel affirmed yesterday in a first-of-its-kind ruling.

The opinion, issued by the 2nd Circuits Chief Judge Robert Katzmann, Judge John Walker, and Judge Rosemary Pooler, affirms a lower court finding by Judge Robert Sweet from last year that found that the NYPD’s Long Range Acoustic Device, or LRAD, is indeed a form of force, “and the kind that could be used excessively.”

The lawsuit was brought by six journalists and protesters who attended a demonstration in Midtown in 2014, and named the police department, the City, and the officers involved.

But before the lawsuit could proceed, the two officers actually involved, Lieutenant John MacGuire and Officer Mike Poletto, appealed the ruling, arguing that they were entitled to qualified immunity.

The officers had argued that they could not be held liable because at the time they deployed the LRAD, there was not clear case law notifying officers that the right against excessive force applies to nonviolent protesters. The court did not find this argument persuasive.

“That is like saying police officers who run over people crossing the street illegally can claim immunity simply because we have never addressed a Fourteenth Amendment claim involving jaywalkers,” it wrote in its opinion.

LRADs were first brought into service in the U.S. Navy as a sound weapon and communication device following the attack on the U.S.S. Cole. The NYPD bought its first LRADs on the eve of the 2004 Republican National Convention, and has used them ever since, primarily for communicating with large crowds, as during Occupy Wall Street and the protests against the police killing of Kimani Gray in East Flatbush in 2013.

But while the LRAD can be used as a super-charged megaphone, it can also function as a crowd-control weapon used to clear spaces, emitting piercing sounds up to 137 decibels, well over the thresholds known to cause pain and even lasting damage in humans.

One man who attended that protest, which was against the Eric Garner grand jury ruling, found himself in the LRAD's cone of sound when the NYPD used it. “It's like being inches from a car alarm going off, except a car alarm goes off after maybe 10 seconds,” he told us.

“It was definitely one of the loudest noises I've ever heard, but I wouldn't say it was immediately pain inducing. But for the next six days, I was feeling pain," he said. "It was like an earache. Any loud noises made it worse.”

The officers had also argued that the protesters had no constitutional protection against the use of LRADs because at the time there wasn’t any clear case law against police use of the sonic weapon, and besides, since LRADs “function solely by sound” they are not "an instrument of force.”

The court didn’t buy those arguments either. “Novel technology,” the court wrote, “does not entitle an officer to qualified immunity.” And LRADs can be a form of force. “Even though sound waves are a novel method for deploying force the effect of an LRAD’s area denial function is familiar: pain and incapacitation,” the court wrote.

The bottom line, Judge Katzmann wrote in his ruling, is that “When engaging with non-violent protesters who had not been ordered to disperse, no reasonable officer would have believed that the use of such dangerous force was a permissible means of moving protesters to the sidewalks. Whatever legitimate interest the officers had in clearing the street, the use of sound capable of causing pain and hearing loss in the manner alleged in the complaint was not rationally related to this end.”

The ruling doesn’t mean that LRADs can’t be used. The court said it remains open to their use as a communication tool, and even, in some circumstances, perhaps, as a crowd dispersal tool.

But when police use LRADs as a form of force, that force must be reasonable.

Gideon Oliver, one of the lawyers representing the plaintiffs in the lawsuit, said yesterday’s ruling is significant because it’s the first ruling of its kind governing police use of sound weapons. “It’s one thing to have a district judge’s opinion, but other district court judges can feel free to disagree,” Oliver said. “A 2nd circuit opinion, a precendential opinion, is binding on the lower courts. And because it’s a circuit court decision, it has much stronger potential to be influential in other circuits around the country.”

The case is now remanded back down to Judge Sweet’s district court, where, barring a settlement, discovery will begin shortly.

In addition to monetary damages related to their injuries, the plaintiffs in the suit are asking for an injunction that would prevent the NYPD from using LRADs without conducting research and coming up with coherent, publicly available guidelines for their use.

You can read the appeals court’s full opinion here.