Can Police Use Tear Gas, Pepper Spray, and Rubber Bullets on Crowds?

When a protest or large gathering turns tense, police often reach for what they call "less-lethal" or "less-than-lethal" weapons: tear gas, pepper spray, pepper balls, rubber bullets, bean-bag rounds, and flash-bang grenades. These tools are legal in the United States, but their use is not unlimited. The Constitution, a growing list of state laws, and a wave of federal court orders all place real limits on when and how officers can deploy them against a crowd.

What counts as "less-lethal" crowd-control force

The label "less-lethal" is a description of intent, not a guarantee of safety. These weapons are designed to cause pain or incapacitation rather than death, but they can and do cause serious injuries and have killed people. The most common categories are:

• Chemical agents: CS and CN gas (commonly called tear gas), usually fired in canisters or grenades, and OC (oleoresin capsicum, or "pepper") spray and pepper-ball projectiles.
• Kinetic impact projectiles: rubber bullets, foam rounds, plastic baton rounds, and bean-bag rounds fired from launchers or shotguns.
• Diversionary devices: flash-bang (stun) grenades that produce a loud blast and bright light.
• Acoustic and other devices: long-range acoustic devices (LRADs) and water cannons in some jurisdictions.

The constitutional limits

Police use of these weapons is governed mainly by two parts of the Constitution. When officers use force to physically stop or restrain a specific person, that is a seizure under the Fourth Amendment, and it is judged by the objective-reasonableness test from Graham v. Connor. Courts weigh the severity of the suspected offense, whether the person posed an immediate threat, and whether they were actively resisting or fleeing. Firing a rubber bullet at someone's head for standing still, or gassing a person who is simply chanting, can fail this test.

When force is used to disperse a crowd generally, rather than to seize one identified individual, courts often analyze it under the Fourth Amendment if a seizure occurred, or under the Fourteenth Amendment's substantive due process "shocks the conscience" standard from County of Sacramento v. Lewis. Either way, indiscriminate force against peaceful people is hard to justify. And because protest is expression, retaliating against demonstrators for their speech can also violate the First Amendment, which protects peaceful assembly subject only to reasonable time, place, and manner restrictions.

One more principle matters: any "less-lethal" weapon can become deadly force depending on how it is used. Tennessee v. Garner and Graham v. Connor make clear that force likely to cause death or serious injury is justified only against an imminent threat of death or serious bodily harm. A bean-bag round to the chest at close range, or a gas canister fired directly at a person's head, can cross that line.

When courts have found crowd-control force excessive

During the 2020 protests, federal judges across the country issued temporary restraining orders and injunctions limiting these weapons after finding that police had used them indiscriminately against peaceful demonstrators, medics, journalists, and bystanders. Examples include Black Lives Matter Seattle-King County v. City of Seattle, Don't Shoot Portland v. City of Portland, and Abay v. City of Denver. The common thread in these rulings was not that tear gas or rubber bullets are always illegal, but that blanket deployment against people who were not threatening anyone, and who had no realistic chance to leave, was not reasonable.

That distinction is the heart of the law. Force is most defensible when there is genuine violence, a real threat to officers or the public, or destruction of property, and when police have given a clear, audible dispersal order with a safe exit route and enough time to comply. It is most vulnerable to challenge when it is sudden, aimed at peaceful people, targeted at heads and necks, or used as punishment for protected speech.

State and local restrictions

Beyond the Constitution, a number of states and cities have passed laws restricting these weapons. California's AB 48 sharply limits when police may use kinetic energy projectiles and chemical agents for crowd control, bars aiming them at the head or neck, and forbids using them solely because someone disobeyed a dispersal order or used offensive language. Cities including Seattle, Portland, and others have adopted bans or moratoriums on tear gas at various points. These rules vary widely, change often, and some bans have been challenged or paused in court, so the law where you live may be very different from a neighboring state.

This article is general legal information, not legal advice. Crowd-control law varies significantly by state and city and depends heavily on the specific facts. For advice about your situation, talk to a lawyer licensed in your state.

A note on the international rules

People are often surprised to learn that tear gas is banned as a method of warfare under the Chemical Weapons Convention, yet remains legal for domestic law enforcement and riot control. That treaty carve-out is why police can deploy a chemical that soldiers cannot use against an enemy army. It does not mean police use is unlimited, only that the limits come from U.S. constitutional and statutory law rather than the laws of war.

Practical safety guidance

If you choose to attend a protest, planning ahead reduces your risk:

• Wear nonflammable clothing that covers your skin, and bring sealed goggles that form a tight seal. Contact lenses trap chemicals against the eye, so wear glasses instead if you can.
• A well-fitted respirator (N95 or better) helps with chemical agents, though nothing fully prevents exposure.
• If you are exposed to tear gas or pepper spray, move upwind and uphill to fresh air, stay calm, and avoid rubbing your eyes or face. Flush eyes and skin with plenty of clean water. Do not use oils, milk, or lotion on the skin before decontaminating with water.
• Listen for dispersal orders and identify exit routes when you arrive, before any chaos starts.
• Document what you see. You generally have a First Amendment right to record police in public. Note officer names, badge numbers, and the time and place, and save any video.
• If you are injured by a munition, seek medical care promptly, photograph your injuries, and keep the clothing you were wearing as evidence.

Being hit by these weapons, or watching it happen, can feel overwhelming. Knowing the legal limits ahead of time helps you make calmer decisions, protect yourself, and preserve your ability to hold officers accountable later if the force used was unreasonable.