U.S. law enforcement agencies increasingly deployed three crowd-control weapons in dangerous ways to crack down on immigration protests over the past year, according to a new visual investigation by Physicians for Human Rights (PHR).
The PHR visual investigation spotlights these three weapons (scattershot impact projectiles, Muzzle Blast rounds, and chemical obscurants), unpacks their health hazards, and analyzes how U.S. law enforcement agencies abused these weapons during immigration protests since June 2025. PHR finds:
- The Los Angeles Police Department’s (LAPD) use of scattershot munitions against journalists and protesters is harmful, indiscriminate, and unusual – yet condoned by LAPD’s internal protocols. Inherently imprecise, scattershot munitions – which fire multiple rounds simultaneously in an expanding dispersal pattern – are tools of collective punishment on assemblies that have rarely been seen in the United States before now.
- U.S. Border Patrol (USBP) agents have fired powder blast dispersion rounds (commonly referred to as “Muzzle Blast” rounds) directly at the faces of protesters, exacerbating health harms. These weapons were previously seen primarily inside of jails and prisons – and now are being deployed on U.S. streets against peaceful demonstrators.
- U.S. Customs and Border Patrol (CBP) use of chemical obscurants (commonly known as “smoke grenades”) are often misunderstood, due to their unclear role in crowd control and the lack of government transparency around which type(s) of smoke is deployed. Some chemical obscurants are more dangerous than others. The widespread misinformation that naturally arises from this ambiguity can compound fear and chilling effects on the right to peaceful protest.
“We have analyzed hundreds of incidents of U.S. law enforcements agents abusing crowd-control weapons against peaceful protesters – and the severe health outcomes experienced by people who were shot or otherwise harmed,” said Rohini Haar, MD, MPH, visual investigation co-author, medical advisor at PHR, and adjunct professor of epidemiology at UC Berkeley. “We have documented how nonviolent protesters have lost their eyes, suffered broken bones, and experienced concussions due to these weapons – as well as psychological consequences for victims and others at these protests. Together, these incidents illustrate a concerning trend in which public dissent is increasingly met with escalating weapons use.”
“The fear and harm resulting from the increasing use of these crowd-control weapons by both federal and local law enforcement demonstrates the need for public disclosure and regulations around these weapons to ensure use complies with internal protocols, international standards, and constitutional guarantees to freedom of assembly,” said Dr. Haar.
Tools of Repression: How U.S. Law Enforcement Escalated the Use of Three Weapons to Crack Down on Immigration Protests includes in-depth video analyses of the three weapons being deployed in novel and harmful ways, alongside text case studies and three new weapons factsheets. The project draws on four decades of research on crowd-control weapons conducted by Physicians for Human Rights, including the seminal Lethal in Disguise report, developed in partnership with International Network of Civil Liberties Organizations (INCLO), most recently updated in 2023.
These three weapons – scattershot impact projectiles, Muzzle Blast rounds, and chemical obscurants – have been widely unrecognized, misidentified, or mischaracterized in media reporting over the past year. Simultaneously, there is scant transparency from law enforcement or manufacturers about the use or health harms of these weapons. The result is a U.S. public whose rights to peaceful assembly are infringed upon and whose physical safety is threatened by an ever-expanding arsenal of unregulated and often-unknown weaponry.
Three Case Studies Detail Weapons’ Harms:
In case #1, PHR’s investigation finds that while most American police protocols recommend kinetic impact projectiles like rubber bullets to target single individuals engaged in assault or violent conduct, LAPD protocols are unique because the agency permits scattershot projectiles to be used against multiple individuals and calls for these weapons to be fired in a way that increases the risk of indiscriminate harm: skip-firing the projectiles off the ground before hitting protesters. LAPD protocols exacerbate the risks such inherent in scattershot projectiles, which fire multiple rounds simultaneously and are prone to hit bystanders as was the case in L.A. where nearly 100 journalists were shot with less-lethal weapons during the anti-ICE protests in the summer of 2025. The imprecision built into these weapons makes them inherently indiscriminate and unsuited for use in crowd control. PHR calls on the LAPD and all law enforcement agencies to ban the use of scattershot projectile weapons.
In case #2, PHR finds that USBP is increasingly using Muzzle Blast rounds, which discharge a plume of pulverized CS (tear gas compound) or OC (pepper agent) in a cloud that extends up to 30 feet in front of the shooter from the muzzle of the weapon. However, from Oakland to Chicago, USBP agents have fired these rounds at point-blank range directly at nonviolent protesters – resulting in facial, eye and neck injuries from the wadding and other traumatic impacts as well as concentrated chemical exposure. Ambiguous manufacturer guidelines and opaque law enforcement protocols must be clarified and improved to ensure compliance with safe practices for these weapons.
In case #3, PHR finds that CBP use of chemical obscurants (smoke grenades) has spurred fear and misinformation. While most types smoke grenades pose relatively few health risks, the understandable confusion of chemical obscurants with far more hazardous substances – such as chemical weapons – contributes to an environment of fear and a chilling effect on protests. The lack of regulations around smoke obscurants in the United States allows for potentially unlimited use and potential abuse. HC smoke (not known to be used in the U.S. since 2020 protests in Portland, Oregon) does pose long-term risks of lung injuries, metabolic issues, and cancers, and should be banned by U.S. authorities, while other chemical obscurants should be evaluated and restricted.
“All three of these weapons reflect the trend of how U.S. law enforcement is increasingly treating civilians not as members of civic society, but rather enemies or combatants. It’s no coincidence that these weapons are coming from either the prison system (Muzzle Blast rounds), the military (chemical obscurants), or both (scattershot impact projectiles),” said Scott Reynhout, PhD, investigation co-author and PHR expert. “To have these weapons increasingly deployed on U.S. streets signals a new low for the militaristic and carceral treatment of U.S. protesters.”
Informed by these findings, PHR calls for prohibitions on scattershot projectiles and HC smoke, as well as enhanced regulations on Muzzle Blast rounds and chemical obscurants. The design, trade, and use of all crowd control weapons must comply with international laws and standards, including the United Nations guidance on crowd-control weapons, which PHR advised on. Law enforcement agents who misuse these weapons should be held to account.
Physicians for Human Rights (PHR) is a New York-based advocacy organization that uses science and medicine to prevent mass atrocities and severe human rights violations. Learn more here.