Court proceedings that could determine the fate of the NYPD's use of military-grade sound cannons, also known as LRADs, got underway Thursday as lawyers representing a group of six protesters, journalists, and everyday bystanders made their case to a U.S. District judge.

The plaintiffs allege they suffered injuries and had their constitutional rights violated when officers blared a high-pitched siren noise from one of the LRADs to disperse protesters from the intersection of 57th Street and Madison at roughly 1 a.m. on December 5th, 2014, where they had been protesting a Staten Island grand jury's decision not to indict the police officer who killed Eric Garner with a prohibited chokehold.

Video recorded during the incident (below) shows people rushing away from the piercing LRAD siren—a technique the device's manufacturer describes as "area denial," but which Keegan Stephan, one of the case's plaintiffs, insists is a First Amendment violation.

"I was trying to record this arrest when I was hit with it," Stephan told NY1. "It forced me away from filming the arrest and the police activity I was trying to film."

"I suffered extraordinary pain," he added "I had to leave the area."

Arguing that U.S. District Judge Robert Sweet should allow the case to proceed, attorney Gideon Oliver stressed that high-decibel LRADs constitute a use of excessive and indiscriminate force.

"Sound waves by operation of physics can constitute uses of force and cause injury," Gideon said Thursday, according to Newsday. "The NYPD is treating an LRAD as if it's just a bullhorn, when it clearly is not."

LRADs were first used by the NYPD in 2004 to suppress crowds during the Republican National Convention, and have since become a regular tool of protest suppression. A truck-mounted LRAD was aimed at Occupy Wall Street protesters attempting to shut down the Brooklyn Bridge in 2011; more recently, over a half-dozen Black Lives Matter marches have been blasted by portable LRADs.

As Newsday notes, the NYPD has no official use-of-force policy for the LRAD, and no past court rulings serve as a guideline for how they might be deployed without causing injury or trampling the Bill of Rights.

"If we are going to use this in New York City, we need to have testing, we need to have training, we need to have guidelines," Elena Cohen, another attorney for the plaintiffs, told NY1.

City attorney Ashley Garman has been tasked with defending the Department's LRAD use, and argued Thursday that the noise cannons were actually a tool for keeping New Yorkers safe. "In order to make the street safe for protesters and provide for the flow of traffic, the use of the LRAD was justified and not arbitrary," Garman said yesterday.

Citing video of the 2014 incident in question, Garman argued the noise was minor. "People were walking way casually, they're not running, not screaming, not covering their ears," she told Sweet.

The lawsuit seeks not only damages for the plaintiffs, but changes to NYPD policy that curtail the use of LRAD devices. Justice Sweet has yet to rule on whether the case will proceed. In an email, Oliver explained to Gothamist why his clients feel the case is so important:

In addition to money damages and attorney’s fees, our clients are seeking injunctive relief to prevent the NYPD from using LRADs for crowd control purposes without appropriate testing, training, guidelines, and supervision.

Since other police agencies often model their policies and practices on the NYPD’s, it’s critical the NYPD fill the current voids in those areas with best practices that treat LRAD uses as serious uses of force and meaningfully constrain LRAD uses for crowd control purposes. LRADs should be handled at least as seriously as other tools the NYPD uses for crowd control such as pepper spray, tear gas, police horses, and the like are treated.