Subtitles section Play video Print subtitles Narrator: Much of the coverage of the 2020 protests against police misconduct in the United States has looked a lot like this, shrouded in a thick cloud of tear gas. [people shouting] Some of the sounds in this video may be shocking. [explosion] And some of the footage may be disturbing. [explosion] - Back up! Reporter: Police on the roof are firing volley after volley of tear gas. Nobody was doing anything. Reporter: Step back, get back, get back, get back! You're ahead, you're ahead. Reporter: There is so much gas that has been launched again that you can barely even see that line of officers. [explosion] Narrator: The use of tear gas has almost become synonymous with the protests, and it's nothing new. [people screaming] [explosion] On June 1, law-enforcement officers used a variety of less-lethal weapons on peaceful protesters outside the White House, creating a scene eerily similar to one from nearly a century ago. In 1930, police used tear gas to disperse a group of unemployed demonstrators in front of the White House. Announcer: Washington became a battleground. Narrator: Two years later, President Herbert Hoover authorized the use of tear gas on American veterans gathered in Washington to demand their promised, yet unpaid bonuses. Announcer: Using tear gas, the troops methodically set about dispersing the marchers in as bloodless a manner as possible. Narrator: In the decades that followed, law-enforcement agencies around the world commonly dispersed large assemblies of protesters with tear gas. But tear gas was initially developed as a weapon of war. So how did it become the weapon of choice against protests? Today, the business behind tear gas is worth billions. Announcer: Reliability and high performance are our binding guarantee. Narrator: Less-lethal weapons, as they're called, are weapons intended to limit the escalation of conflict without lethal force. This industry was worth about $6.3 billion in 2016 and is projected to grow to $11.3 billion by 2023. Tear gas represents about 25% of the industry, meaning by 2023, it could be worth about $3 billion a year. Anna Feigenbaum: This is completely a for-profit industry. Narrator: This is Anna Feigenbaum, the author of a book about the history of tear gas. Feigenbaum: There is constantly new innovation in this industry. We're seeing pushes to put more and more equipment into police hands. [explosion] Narrator: And the industry's rise is tied to why it was originally developed. The first known use of tear gas was in World War I, when French soldiers fired tear gas grenades into German trenches. It was one of many chemical weapons used in the war, during which over 90,000 soldiers died from exposure to poisonous gases. Announcer: A meeting of European foreign ministers in Locarno, Switzerland. Narrator: A 1925 treaty known as the Geneva Protocol banned the use of "asphyxiating, poisonous or other gases" in combat. But the United States would not ratify the agreement until 1975 and held the stance that the protocol did not apply to nontoxic gases or chemicals that could be used for riot control. Other countries disagreed. Jamil Dakwar: The idea was that if you allow tear gas to be used in armed conflict situations, there could be escalation of other chemical weapons that would be increasingly dangerous and would cause mass casualties. Narrator: And the protocol also did not limit production of those weapons, so production of tear gas grew. [gas spraying] Feigenbaum: The Chemical Warfare Service, which had been doing a lot of this R&D, wanted to continue. And there was a big push to try and validate its continued existence. And one of the main drivers of that push was a guy named Gen. Amos Fries. He decided that tear gas could have a lot of uses for security and for law enforcement. And so he worked to create this kind of commercial or domestic market in tear gas. Announcer: The jumper repeater grenade discharges three large blasts of tear gas in rapid succession. Narrator: Categorized as a less-lethal weapon, tear gas is defined by the CDC as any chemical agents that "temporarily make people unable to function by causing irritation to the eyes, mouth, throat, lungs, and skin." Announcer: Six smoke-filled jumper repeater grenades make an impressive display of saturation. Narrator: Tear gas manufacturers aggressively marketed their products to law-enforcement agencies. - How are you, Mr. Matthews? - Stick 'em up! Narrator: Like in this promotional film from 1930 that illustrates how tear gas can be used to thwart bank robbers. - That's my last job. Narrator: The marketing worked. - Well, it's better than being shot. Narrator: Tear gas became a weapon of choice for police tasked with dispersing large crowds. Announcer: With the army on the way, the strike scene is hectic. Narrator: In the early 20th century, police often used tear gas during labor strikes. Announcer: Then comes trouble, and police tear gas. [explosion] [people shouting] After the pin is pulled, the grip on the strap handle controls the firing mechanism. Narrator: Manufacturers weren't just selling tear gas itself. Announcer: When the handle is released in throwing, the grenade is activated. Narrator: They were also hawking must-have accessories. Announcer: In a special kit available for immediate use is a complete assortment of gas munitions, including projectiles and grenades. Narrator: And throughout the 20th century, tear gas was used more frequently on protesters around the world. In Japan, Germany, Malaysia, Vietnam. Announcer: South to Saigon, tear gas has been used to crush recent street rioting. [explosion] Narrator: Northern Ireland. Announcer: Washington police used tear gas to drive them away. Narrator: Back in the US, police continued to wield it on protesters. Along with labor strikes, police used tear gas at political and human rights protests, like the 1965 Civil Rights protests in Selma, Alabama. And in 1969, when police used tear gas to disperse groups protesting the Vietnam War. Feigenbaum: There was resistance and people saying, "Well, how can you ban this in war but then allow it here? How could we have said that these chemicals have no place as part of military strategy, and then you're using it on civilians?" And so that strangeness or almost what seems like an absurdity of that exceptional clause has long been pointed out. Narrator: But the United States always had exceptions when it came to tear gas. The country used tear gas and other chemicals during the Vietnam War, both abroad and at home. [explosion] [people shouting] More limitations were put in place in 1993 with the Chemical Weapons Convention, a treaty that explicitly banned agents like tear gas "as a method of warfare." [explosion] But it still did not ban its usage in law enforcement, including riot-control instances.