Tear Gas: Illegal in Warfare, Legal in Ferguson

International law bans the use of tear gas in warfare, but it’s legal as a form of crowd control. Oppressive regimes use it to quell political dissent in places like Bahrain and Egypt. But images from protests in Ferguson, Missouri – with tear gas clouding the sky and protesters fleeing for cover – show that the use of tear gas is alive and well in the United States.

You know something is wrong in when activists in the Middle East need to give your citizens tips on how to deal with tear gas and excessive police force.

Tear gas is a chemical weapon that triggers pain receptors, which leads to tear and mucous production and muscle cramps in the eyelids. Sven-Eric Jordt, a Duke University scientist, told Vox that “there are situations where [tear gas] can be very dangerous or lethal,” especially if someone has a preexisting condition like asthma. The excess mucous production can make someone feel like they are suffocating. Very little is known about its long-term effects, though Jordt is currently researching them. “I’m very concerned that, as use has increased, tear gas has been normalized,” he says. “The attitude now is like, this is safe and we can use it as much as we want.”

Often, it’s not the gas itself but the canister that causes injury and death. In Bahrain—a close US ally—the police and security forces have killed pro-democracy protesters with gas canisters. The United States and South Korea stopped exporting tear gas to Bahrain. But the U.S. government continues to ship tear gas to Egypt, where the new military dictatorship has used it on peaceful protestors.

But when U.S. police departments are dousing Americans with tear gas, it’s difficult for the government to make a compelling case against its use abroad.