The Chemical Weapons Convention

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The Chemical Weapons Convention (CWC) and the law enforcement exception


The Chemical Weapons Convention (CWC) opened for signature in 1993 after more than a decade of negotiations in the Conference on Disarmament (CD). It entered into force in 1997 and has, as of January 2016, 190 States Parties.

In contrast to the 1925 Geneva Protocol, which only bans the use of chemical weapons, the CWC prohibits the development, acquisition, transfer, and stockpiling of chemical weapons, including equipment designed specifically for their use and delivery. The Convention comprises a Preamble, 24 Articles, and 3 Annexes (an Annex on ‘chemicals’, an Annex on ‘verification’, and an Annex on ‘confidentiality’). The aim of the Convention is to completely eliminate chemical weapons and to make sure that they remain so.

In addition to stipulating the unconditional prohibition and elimination of chemical weapons, the CWC established the Organisation for the Prohibition of Chemical Weapons (OPCW), and mandated the implementation of an OPCW inspection regime. The CWC encompasses all types of chemical agents, but contains wide exceptions for dual use agents meant for purposes other than warfare. One such exception is chemical agents used for law enforcement. A unique provision of the CWC is the so-called ‘challenge inspection’, through which a State Party can request the Director-General of the OPCW to dispatch an inspection team to any State Party with no right of refusal.

The CWC does not ban chemical agents meant for use in ‘law enforcement including domestic riot control’. The Convention defines riot control agents (RCA) as ‘[a]ny chemical […] which can produce rapidly in humans sensory irritation or disabling physical effects which disappear within a short time following termination of exposure.’ In other words, riot control agents have temporary effects. An example of a chemical agent allowed in law enforcement, but with permanent effects, is chemicals used to carry out the death penalty. States Parties can manufacture and use riot control agents and other chemical agents for the purpose of law enforcement if they report such manufactures to the OPCW, and if their stockpile is consistent with domestic use purposes.

The most common riot control agent (RCA) is 2-chlorobenzalmalononitrile, commonly known as CS. CS is an airborne agent consisting of powder mixed with smoke, and is the defining component of so-called tear gas. The Convention bans all RCAs from use in warfare, mainly due to probable difficulties in implementing the chemical weapons prohibition in warfare if certain types of chemical agents were allowed.

The text of the CWC leaves ambiguities with regard to the law enforcement exception. Use of chemicals for the purpose of law enforcement including domestic riot control is not prohibited under the convention. This distinction, however, is not always straightforward as a chemical can have both temporary (RCA) and permanent harmful effects. While RCAs are clearly permitted, there is debate as to whether other chemical agents can be used for law enforcement. This question arose with regard to the theatre siege incident in Russia in 2002. Here, Russian authorities used fentanyl, an opioid analgesic, to incapacitate the terrorists that had taken hostages inside the theatre. The fentanyl killed fifty hostage takers and approximately 125 hostages, suggesting that the effects of the agent were not ‘temporary’. It has been argued that the hostage taking should be viewed as a part of the Second Chechen War, and consequently that the operation was one of an armed conflict, and not law enforcement, in which case use of any chemicals would be prohibited.

Second, the CWC does not define ‘law enforcement’ and ‘method of warfare’. The term ‘method of warfare’ strongly indicates that this is a reference to hostilities in an armed conflict. Questions have been raised as to whether ‘domestic riot control’ does apply in international peace operations – in situations that do not reach the threshold of armed conflict. While certain states have looked at peacekeeping and humanitarian missions as ‘law enforcement’, others claim that this could be a violation of the Convention because such operations are not ‘domestic’. Recent counterinsurgency operations, such as in Afghanistan and Iraq, have further challenged the distinction between law enforcement and armed conflict.