Tear gas, a chemical weapon, is banned in warfare but permitted in law enforcement and on American streets.

The chemical compound is designed to target pain receptors, inflame the lungs and debilitate by causing temporary blindness and difficulty breathing; the body reacts and if enough is inhaled you are rendered unable to function. It's use has the potential to increase the spread of the coronavirus and to cause long-term harm in people with asthma and other respiratory conditions. Scientists still know little about the effects of repeated and high-level exposure.

So why is tear gas used regularly in Portland and other American cities?

According to the ACLU, “This really goes back to the Chemical Weapons Convention. At the time when it was negotiated in the 1990s, there was a a lot of pressure to ban chemical weapons and they were used by law enforcement. That got pushback from many countries who said, “Well, we can’t really give up this weapon because if we don’t use tear gas we will have to resort to more lethal weapons.”

The compromise reached left open the option to use tear gas and other riot control agents in law enforcement, and only in law enforcement.