According to the complaint filed Wednesday, the US government violated the National Environmental Policy Act by deploying dangerous chemical weapons without assessing their impact on the environment.

Despite being banned in warfare for nearly a century, tear gas has been a common tool used by law enforcement to break up crowds of protesters. Now—after more than 100 days of ongoing racial justice protests that began after the police killing of Minneapolis resident George Floyd—environmental groups represented by the ACLU of Oregon are demanding the use of this harmful chemical agent end. 

A federal lawsuit filed Wednesday is seeking a court order to stop federal officers from deploying tear gas in Portland until the Department of Homeland Security performs and makes public a “thorough analysis” of the environmental and health impacts of the chemical weapon.

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According to the complaint, the US government violated the National Environmental Policy Act by deploying dangerous chemical weapons without assessing their impact on the environment. “The manner and volume of tear gas and other munitions deployed in relation to Operation Diligent Valor in Portland has been so excessive and substantial,” it states, “that visible munitions residue and sediment have accumulated in and on Portland’s streets, sidewalks, curbs, bioswales, stormwater system, buildings, and standing water, and have been transported and conveyed to the Willamette River banks and waters.”

The lawsuit also points out that the egregious lack of knowledge on the substance deployed at will is most likely to disproportionately affect people of color. It joins at least two other lawsuits from Portland activists demanding an end to violent action from law enforcement against Black Lives Matter protesters, as well as municipal action to defund the police in response to the same violence. 

In July, over a month after demonstrations in Portland had been going strong, DHS officers were sent to the city by the Trump administration, which further escalated nightly standoffs between citizens at federal buildings and local law enforcement. It was then that protesters and journalists began anecdotally discussing a seemingly stronger chemical agent, coming specifically from the federal officers.

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A recent study from a Portland group called Chemical Weapons Research Consortium appears to confirm that the agent the feds brought in, identified by researcher Juniper Simonis in the September report as  Zinc Chloride (ZnCl2), was “exceptionally toxic.” 

Like all forms of tear gas, the long-term effects on personal health and general environment is largely unknown. But at least a dozen protestors told The Intercept’s Sharon Lerner that the effect of this gas was markedly and instantly more harmful on their bodies. 

Now, environmental groups are claiming a lasting and detrimental effect on the environment, particularly on runoff into rivers, affecting water supply.

“Environmental hazards and police violence disproportionately deny that right to Black, Indigenous, Latinx and other people of color,” Kelly Simon, Interim Legal Director with ACLU Oregon, said of the lawsuit. “The large volumes of tear gas and other chemical weapons that federal officers recklessly and thoughtlessly unleashed in Portland is yet more evidence of the Trump administration’s racist disregard for public health and a safe living environment. So we will see them in court, again.”

The use of tear gas by police during the COVID-19 pandemic, when poor respiratory health can be life-threatening, was met with horror by many throughout the most visible portion of protests, by both Black Lives Matter supporters and medical professionals

Police have always defended their use of tear gas, along with riot gear such as night sticks used to strike dissenters, as a form of “crowd control.” But a 2012 report by Physicians for Humans Rights on police violence in Bahrain found that tear gas in particular was more accurately described as a punishment by police, with no real effect on “crowd control” at all. In fact, the painful agent is much more likely to result in confusion and fear, leading to more disarray—which can lead the police to more violent action in response.

The ACLU’s lawsuit calls for an immediate end to the DHS’s deployment of the agent.

“I’ve been on the ground facing tear gas and police brutality for months because racial justice and climate justice are faces of the same struggle for a just and livable future, one that as a young person of color I expect to be in all my life,” Indi Namkoong, a representative of 350PDX, one of the five environmental groups filing with the ACLU, said of the lawsuit. “The price of justice shouldn’t be further harm to public health and to the Black, Indigenous, and other people of color who are already out here fighting for their lives.”

READ MORE: The DOJ Thinks Portland, Seattle, and New York Are ‘Anarchist’ Cities. Data Shows Why That’s Not True.