Is Firing Tear Gas Across Borders Legal?

On January 1, 2019, U.S. Border Patrol agents fired tear gas into Mexico to deter a group of about 150 Central American migrants from crossing into the U.S. near Tijuana. This incident has sparked debate about whether U.S. Border Patrol agents are legally permitted to fire tear gas into Mexico. While tear gas has been outlawed as a method of warfare, its use in domestic law enforcement is permitted, and U.S. authorities have defended their actions as a necessary response to rock-throwing migrants. However, critics argue that firing tear gas into another country violates international law and human rights norms, especially when the affected individuals include peaceful men, women, and children seeking asylum.

The Chemical Weapons Convention permits tear gas in law enforcement

The Chemical Weapons Convention, which was opened for signature on 13 January 1993 and enforced on 29 April 1997, banned the use of tear gas in warfare. However, it permitted the use of tear gas in law enforcement, a decision that has been controversial. The convention includes an express exception for domestic law enforcement, including riot control.

The compromise was that less-than-lethal effects were permitted to conduct internal civil control actions while maintaining adherence to the Chemical Weapons Convention (CWC). This is similar to expanding bullets, which are banned in war because they cause superfluous harm but are permitted in law enforcement because that consideration isn't relevant and they have decent stopping power.

The use of tear gas dates back to World War I when soldiers used it to incapacitate enemy troops. In 1925, the Geneva Convention categorized tear gas as a chemical warfare agent and banned its use during wartime. However, its use by police in the U.S. is still technically legal. In the 1990s, after the Cold War accelerated the development and stockpiling of chemical weapons, there was international pressure to ban law enforcement from using the agent. However, some countries argued that if police couldn’t use tear gas, they’d be forced to resort to more lethal weapons to quell uprisings.

Tear gas is a chemical weapon that causes a person's eyes to burn and produce tears and makes breathing extremely painful and difficult. It is intended to hurt. Most law enforcement agents in the U.S. use a chemical called 2-chlorobenzalmalononitrile, or CS, to create the weapon. The compound activates the same pain receptor that gets triggered by eating wasabi.

Border Patrol's use of tear gas violates human rights norms

The use of tear gas by Border Patrol agents on migrants at the US-Mexico border has sparked controversy and raised concerns about potential human rights violations. While US Border Patrol agents have justified their actions as a necessary use of force to protect themselves and maintain order, the deployment of tear gas in this context has been criticised as inhumane, excessive, and a violation of international human rights law and norms.

On multiple occasions, US Border Patrol agents have fired tear gas into Mexico to deter migrants from crossing the border and to target those throwing rocks. These incidents have involved migrants, including women and children, who were seeking asylum and exercising their right to do so at an international border. Under international human rights law, the use of force by border officials is permitted only when necessary and must be proportionate to the seriousness of the offence. In the context of migrants, many of whom are unarmed and pose no immediate threat, the use of tear gas can be seen as a disproportionate and excessive use of force.

Tear gas, also known as a "riot control agent," has been banned as a method of warfare by the Chemical Weapons Convention. While the convention permits its use in law enforcement, this decision has been highly controversial. The use of tear gas can cause physical injury, permanent disability, and even death, with children being especially vulnerable to its effects. Infants exposed to tear gas can develop severe pneumonitis and require extended hospitalisation. Thus, the use of tear gas by Border Patrol agents, particularly against vulnerable populations, can be seen as a violation of human rights norms, including the right to health and the right to be free from cruel, inhumane, or degrading treatment.

Furthermore, the use of tear gas at the border can also impede the right to seek asylum. The long wait times and cumbersome processes at official ports of entry have discouraged migrants from seeking asylum through proper channels. As a result, some migrants have resorted to crossing the border wall and handing themselves in to Border Patrol agents. The use of tear gas in these instances not only deters migrants from exercising their legal right to seek asylum but also puts them in dangerous and potentially life-threatening situations.

The Border Patrol's use of tear gas at the US-Mexico border has highlighted the need for a re-evaluation of the use of chemical agents in law enforcement, especially in contexts involving vulnerable populations and the exercise of fundamental human rights, such as the right to seek asylum. While maintaining border security and the safety of Border Patrol agents are important considerations, these must be balanced with respect for human rights and the proportionality of force employed.

Tear gas is banned as a method of warfare

The use of tear gas, a chemical weapon that stimulates the nerves of the lacrimal gland in the eye to produce tears, is banned in warfare by the international Chemical Weapons Convention (CWC). The CWC, which the US ratified in 1993, prohibits the use of toxic chemicals in war, defined as:

> any chemical, regardless of its origin or method of production, which, through chemical action on life processes, can cause death, temporary incapacitation or permanent harm to humans or animals.

The Geneva Protocol of 1925 also prohibited the use of "asphyxiating gas, or any other kind of gas, liquids, substances or similar materials", a treaty that most states have signed.

Despite this, tear gas is still used in law enforcement and civilian self-defence. In 2019 and 2021, US Border Patrol agents fired tear gas into Mexico to disperse migrants attempting to cross the border fence near Tijuana. This action was defended by the Department of Homeland Security, who stated that the border patrol agents responded with “appropriate force” to defend themselves from a "violent mob". However, critics argue that the use of tear gas on a crowd of unarmed, largely peaceful migrants, including children, violated human rights norms.

The American Civil Liberties Union (ACLU) has called for the domestic use of tear gas to be prohibited, stating that it is an indiscriminate and terrifying weapon that does not "control riots". The effects of tear gas can be severe, causing choking sensations, skin burns, coughing, difficulty swallowing, and in some cases, blindness and respiratory failure. In addition, the long-term consequences of exposure to tear gas are still unclear, particularly for children.

Border Patrol's use of tear gas was disproportionate

The use of tear gas by US Border Patrol agents against migrants at the US-Mexico border has been a highly controversial issue. While Border Patrol agents have argued that the use of tear gas is necessary to protect themselves and maintain order, critics have characterized it as a disproportionate response, especially when children are present.

On multiple occasions, US Border Patrol agents have fired tear gas into Mexico to disperse migrants attempting to cross the border. In one instance, agents used tear gas to target rock throwers who were separate from a group of migrants trying to cross. In another incident, agents fired tear gas at migrants, including women and children, who were attempting to climb the border fence to get to San Diego from Tijuana.

The use of tear gas by Border Patrol agents has been defended by government officials as an "accepted use of nonlethal force" to protect themselves and maintain order. Department of Homeland Security spokesperson Katie Waldman, for example, stated that border patrol agents responded with appropriate force to defend themselves from a "violent mob."

However, critics have argued that the use of tear gas on a crowd of largely peaceful migrants, including children, is disproportionate and a violation of human rights norms. Under international human rights law, the use of force by border officials must be necessary, proportionate to the seriousness of the offense, and justified by a legitimate objective. The presence of children in the crowd further complicates the use of tear gas, as studies suggest that children are more vulnerable to severe injuries from chemical toxicity.

The Chemical Weapons Convention, which entered into force in 1997, banned tear gas as a method of warfare but permitted its use in law enforcement. Despite this controversial compromise, the use of tear gas by law enforcement has been widely criticized, and there have been calls for its use to be banned. The use of tear gas by Border Patrol agents at the US-Mexico border has been no exception to this criticism, with many arguing that the use of tear gas in these situations is disproportionate and unnecessary.

Tear gas was fired to target rock throwers

On January 1, 2019, U.S. Border Patrol agents fired tear gas into Mexico, affecting a crowd of about 100-150 migrants, including women and children, who were attempting to breach the border fence near Tijuana. The U.S. Customs and Border Protection (CBP) stated that the use of tear gas was targeted at rock throwers who were separate from the group of migrants attempting to cross the border.

According to the CBP, the tear gas was used to defend its agents from rocks and other projectiles being thrown. The CBP's statement said that its agents could not assist the children because of the rocks being thrown and that the chemical agents were targeted at rock throwers who were further away from the fence. However, journalists and photographers at the scene reported that they saw at least three volleys of tear gas launched onto the Mexican side of the border, affecting migrants, including women and children, as well as journalists.

The use of tear gas in this context has been controversial. While the CBP defended its actions as a necessary use of force to maintain order and protect its agents, critics argue that the use of tear gas on a crowd of largely peaceful migrants, including children, violated human rights norms and civil and human rights. Tear gas has been outlawed as a method of warfare by the Chemical Weapons Convention, but its use in domestic law enforcement is permitted, which has been a point of contention.

The incident highlighted the tensions and challenges faced at the U.S.-Mexico border, particularly with the large number of migrants seeking asylum and the long wait times at official ports of entry. The use of tear gas in this incident sparked debates about the appropriate use of force by law enforcement and the potential impact on vulnerable individuals, such as children.

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