Tear Gas vs. Chemical Weapons: A Legal Contradiction in the CWC

The use of riot control agents is, unfortunately, a common occurrence in today’s political climate. From Black Lives Matter protests in the US to the Arab Spring protests in the Middle East, domestic law enforcement forces have repeatedly used toxic chemicals such as tear gas and pepper spray against civilians.1 However, these substances are typically banned in warfare, presenting an international legal conundrum: Why are toxic chemicals banned in warfare - where soldiers are allowed to kill or severely injure one another - but allowed for use against unarmed civilians in protests?

The Legal Framework: The Chemical Weapons Convention

The Chemical Weapons Convention (CWC)2 bans the use of chemical weapons “under any circumstances” under Art.I(1).3 This prohibition extends to riot control agents, according to Art.I(5). Notably, an exception is allowed for domestic law enforcement, allowing for their use on civilians. 4 This legal distinction has sparked international controversy, namely due to the human rights concerns associated with riot control agents. This article will therefore explore this controversy under an international human rights law lens.

But what is a riot control agent and what does it do?

A riot control agent, such as tear gas and pepper spray, can have severe negative effects upon human mental and physical health. Tear gas is composed of chemical compounds known as chloroacetophenone and chlorobenzylidenemalononitrile, while pepper spray is composed of oleoresin capsicum. 5

Mentally, exposure to these agents can cause panic. Physically, they can induce extreme “tearing of the eyes, breathing difficulties including coughing and choking sensation, chemical burns, vomiting and severe allergic reaction”. 7 More serious consequences include “death by suffocation or as a result of allergic reactions”. 8 Serious consequences are often seen in vulnerable groups, such as pregnant women, the elderly and people with preexisting medical conditions. 9

Furthermore, if these chemical irritants are fired at a crowd and hit a person directly, they cause “penetration wounds, concussion, other head injuries, and in severe instances, death”. 10 As a result of its indiscriminate nature, it is considered to violate the principle of superfluous injury or unnecessary suffering in international humanitarian law. 11 Yet, on the domestic playing field, these chemicals run free among crowds of civilians including those who are especially vulnerable to its adverse effects.

What is the human rights perspective to this?

Under international human rights law, the right to peaceful assembly and the right to protest is protected under several legal instruments, such as Art. 21 of the International Covenant on Civil and Political Rights (ICCPR). 12

Additionally, the UN Basic Principles on the Use of Force and Firearms by Law Enforcement Officials, along with its Code of Conduct for Law Enforcement Officials, mandate that “police must… offer immediate medical and psychological treatment for any injuries” caused by riot control agents. 13 Nevertheless, in many of these cases, police do not fulfill this requirement. 14

The European Court of Human Rights (ECtHR) has made several rulings regarding the use of riot control agents, notably in the Ataman v. Turkey, the ECtHR found that the police use of pepper spray was a violation of Art. 11 ECHR, which protects the freedom of peaceful assembly. 15 In the Abdullah Yasa case, the Court stated that the “direct firing of tear gas at protesters to disperse a non-peaceful gathering was both unnecessary and disproportionate”, thus violating Art. 3 of the ECHR which states the prohibition of torture. 16 These rulings suggest that an emerging human rights norm is challenging the legitimacy of using riot control agents against both peaceful and non-peaceful protesters. If this norm solidifies, this would effectively require law enforcement to use other de-escalation tactics and give priority to the human rights of each protester involved. 17

Addressing the Counterargument

Riot control agents are irrefutably damaging when directed at civilians, however the contradiction between its permissibility under domestic law enforcement and the prohibition of it in armed conflict has been argued by legal experts to be justified. Amnesty International notes that this distinction arises from the different purposes and orientations of force in each context.18 In armed conflict, lethal force is the standard course of action. Therefore, the use of chemical weapons can result in the death of the combatant.

However, with the dangerous nature of many chemical weapons, they can bring about superfluous injury or unnecessary suffering for the combattant, effectively violating a principle of international humanitarian law. 19 In contrast, in domestic law enforcement, “the utmost duty is to protect life” and the use of chemical agents is often framed as a less lethal alternative to other forms of force. 20 However, this reasoning is continuously challenged. The harm inflicted by these agents, coupled with their impact on human rights such as the freedom of assembly should not be disregarded. Given today’s political climate, where protests are a crucial tool for citizens resisting authoritarianism and extreme right-wing policies, the frameworks put in place in international law are failing to protect innocent civilians. 21

Moreover, many legal scholars have noted how the current framework regarding riot control agents is deeply flawed. The CWC, which in fact allows for this exception to the prohibition against riot control agents, has been said to be limited by the political and legal “compromises” made at the time of its negotiations, which result in these “double standards”. 22 The existing structures meant to protect the international community from toxic chemicals are in fact unable to protect civilians trying to demonstrate their human rights.

Conclusion

To uphold international human rights law, the global legal community must recognize the shortcomings of the current legal framework regarding riot control agents. A reassessment of these legal provisions is necessary to ensure greater protection for civilians, and to prevent the indiscriminate use of toxic chemicals against protesters. By addressing this legal loophole, international law can better serve its purpose of safeguarding human rights and fundamental freedoms.

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1 Shireen Daft, 'Tear Gas and Pepper Spray Are Chemical Weapons – So Why Can Police Use Them?' (The Conversation, 17 June 2020) https://theconversation.com/tear-gas-and-pepper-spray-are-chemical-weapons-so-why-can-police-use-them-140364 accessed 21 March 2025.

2 Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction (opened for signature 13 January 1993, entered into force 29 April 1997) 1974 UNTS 45.

3 Ibid, Art. I(1).

4 Ibid, Art. II(9)(d).

5 Shireen Daft, 'Tear Gas and Pepper Spray Are Chemical Weapons – So Why Can Police Use Them?' (The Conversation, 17 June 2020) https://theconversation.com/tear-gas-and-pepper-spray-are-chemical-weapons-so-why-can-police-use-them-140364 accessed 21 March 2025.

6 ibid p.7

7 Amnesty International, Chemical Irritants in Law Enforcement: An Amnesty International Position Paper (Amnesty International Netherlands, June 2021) p 5.

8 Ibid

9 Casey Morin, 'Next Steps in Chemical Weapons Control and Protecting the Right to Protest: Improvements to the Legal Regime Controlling Tear Gas' (2021) 44 Fordham International Law Journal 1267 https://ir.lawnet.fordham.edu/ilj/vol44/iss5/3 accessed 21 March 2025, p 1280.

10 Amnesty International, Chemical Irritants in Law Enforcement: An Amnesty International Position Paper (Amnesty International Netherlands, June 2021) p 7.

11 International Committee of the Red Cross, 'Unnecessary Suffering (or Superfluous Injury)' (How does law protect in war? - Online casebook) https://casebook.icrc.org/a_to_z/glossary/unnecessary-suffering-or-superfluous-injury-0 accessed 21 March 2025

12 International Covenant on Civil and Political Rights (adopted 16 December 1966, entered into force 23 March 1976) 999 UNTS 171, art 21; European Convention for the Protection of Human Rights and Fundamental Freedoms (European Convention on Human Rights, as amended) (ECHR) art 11.

13 Shireen Daft, 'Tear Gas and Pepper Spray Are Chemical Weapons – So Why Can Police Use Them?' (The Conversation, 17 June 2020) https://theconversation.com/tear-gas-and-pepper-spray-are-chemical-weapons-so-why-can-police-use-them-140364 accessed 21 March 2025; United Nations, 'Basic Principles on the Use of Force and Firearms by Law Enforcement Officials' (1990); United Nations, 'Code of Conduct for Law Enforcement Officials' (1979).

14Amnesty International, 'Right to Protest' https://www.amnesty.org/en/what-we-do/freedom-of-expression/protest/ accessed 21 March 2025.

15Abdullah Yaşa and Others v. Turkey, App no 44827/08 (ECtHR, 16 July 2013)

16Oya Ataman v. Turkey, App no 74552/01 (ECtHR, 5 December 2006) ; Natasha Williams, Maija Fiorante and Vincent Wong, The Problematic Legality of Tear Gas Under International Human Rights Law (International Human Rights Program, University of Toronto Faculty of Law 2020) edited by Ashley Major and Petra Molnar p 16.

17 Natasha Williams, Maija Fiorante and Vincent Wong, The Problematic Legality of Tear Gas Under International Human Rights Law (International Human Rights Program, University of Toronto Faculty of Law 2020) edited by Ashley Major and Petra Molnar p 17.

18 Amnesty International, Chemical Irritants in Law Enforcement: An Amnesty International Position Paper (Amnesty International Netherlands, June 2021) p 26.

19 International Committee of the Red Cross, 'Unnecessary Suffering (or Superfluous Injury)' (How does law protect in war? - Online casebook) https://casebook.icrc.org/a_to_z/glossary/unnecessary-suffering-or-superfluous-injury-0 accessed 21 March 2025

20Amnesty International, Chemical Irritants in Law Enforcement: An Amnesty International Position Paper (Amnesty International Netherlands, June 2021) p 25.

21 Amnesty International, 'Right to Protest' https://www.amnesty.org/en/what-we-do/freedom-of-expression/protest/ accessed 21 March 2025.

22 Michael Crowley, Chemical Control: Regulation of Incapacitating Chemical Agent Weapons, Riot Control Agents and Their Means of Delivery (Palgrave Macmillan 2016) reviewed in (2015) 97(899) International Review of the Red Cross 923, doi:10.1017/S1816383116000187, p 923.