Chemical incapacitants: an acute case of fragmentation of international law?

David Fidler raised an important point in discussing the ‘slippery slope ambiguity’ concerning the potential use of novel toxic chemicals for law enforcement purposes and lack of consensus among states to make a prohibition on such a development as comprehensive as possible.

There is a confluence of different types of discussion in the in the debate on incapacitating agents. The licitness of incapacitating agents falls between three specialised areas of law, namely:

• disarmament law, which seeks to eliminate a discrete class of weaponry. Of importance to the present discussion are primarily the Chemical Weapons Convention (CWC) and the Biological and Toxin Weapons Convention (BTWC). Between them, the treaties comprehensively ban the development, acquisition, retention and use of chemical and biological agents, as well as of other substances in the gray area in between, as instruments of warfare. That gray area includes toxins (poisons from living organisms) and a variety of sub-cellular particles, such as bioregulators, which many analysts view as a future threat agent. The prohibitions also cover delivery systems and other equipment specifically designed  for the use of those agents as weapons, and any other type of preparation, e.g., military training in the offensive use of chemical and biological weapons (CBW).
• laws of war (humanitarian law), which essentially try to limit the consequences of the use of weapons in armed conflict. They use different approaches, the most important ones of which are the unreserved ban on the use of certain weapons based on the principle that the means to harm an enemy are not unlimited, proportionality between the causation of harm or destruction and the military objectives, the designation of certain categories of people as non-combatants and certain types of infrastructure as ‘civilian’, and the requirement to discriminate between legitimate military targets and the exempted categories of people and infrastructure. Humanitarian law does not in and of itself restrict the acquisition or possession of particular types of weaponry, nor does it limit preparations for their use. To this category belong with respect to CBW the 1899 and 1907 Hague Conventions, 1899 Hague Declaration (IV, 2) concerning asphyxiating gases, the 1925 Geneva Protocol prohibiting the use of CBW in armed conflict, and the 1977 Environmental Modification  (ENMOD) Convention, which covers the use of anti-plant agents. The CWC reaches into humanitarian law; the Fourth Review Conference of the BTWC (1996) clarified that the core prohibition extended to the use of biological and toxin agents too.
• human rights law, which addresses questions of officially sanctioned used of force against individuals in situations other than armed conflict.

The CWC and BTWC ban CBW under any and all circumstances, i.e. in peace and in war. Parties must transpose the respective international prohibitions into national legislation in order to prevent natural and legal persons from undertaking any type of activity proscribed to states. National military doctrines cannot contain guidelines for offensive chemical or biological warfare operations and military penal codes should be able to address violations. The phrasing in each country may differ; national penalties may vary, but no discussion exists about the absoluteness of the prohibition.

Humanitarian and human rights law, in contrast, essentially leave it up to governments and their agencies or national legislators to determine the extent to which violence is legitimate, and therefore, the types of instruments their armed forces and law enforcement officials can have at their disposal. This underlines an important distinction between disarmament law, on the one hand, and humanitarian law and human rights law, on the other hand. The former controls weaponry for their physical or technical properties; the latter two branches focus on the consequences of their application relative to necessity.

However, in contrast to the laws of war, the debate on incapacitating agents in human rights law focusses mostly on the national level. States define their relationship to the individual in many different ways. They also determine the scope of what types and degrees of officially sanctioned violence are legitimate, and under which circumstances they may be applied. Consequently, they are likely to have different views about the licitness of incapacitating agents for law enforcement purposes. Through the twin processes of expanding national and international criminalisation of individual behaviour of state agents and (international) litigation against perpetrators of particular acts or enablers of such acts, future opinion about the legitimacy of certain types of weapons, such as incapacitating toxicants, might become more uniform. For the time being, however, human rights law appears to face contradictory objectives. The Eighth United Nations Congress on the Prevention of Crime and the Treatment of Offenders held in Havana from 27 August to 7 September 1990 framed the following general principles with regard to the application of lethal force in law enforcement (Document A/CONF.144/28/Rev.1, p. 113):

2. Governments and law enforcement agencies should develop a range of means as broad as possible and equip law enforcement officials with various types of weapons and ammunition that would allow for a differentiated use of force and firearms. These should include the development of non-lethal incapacitating weapons for use in appropriate situations, with a view to increasingly restraining the application of means capable of causing death or injury to persons. […]
3. The development and deployment of non-lethal incapacitating weapons should be carefully evaluated in order to minimize the risk of endangering uninvolved persons, and the use of such weapons should be carefully controlled. (emphases added)

The category of ‘non-lethal incapacitating weapons’ is obviously broader than the topic of this posting. The juxtaposition of ‘non-lethal’ and ‘incapacitating weapons’ nevertheless raises some interesting questions with regard to the CWC. The convention does not use lethality as a defining criterion for CW (it is mentioned as a possible consequence of exposure to a toxicant), nor does it define ‘incapacitating agent’. ‘Incapacitation’ is mentioned four times, but never in direct proximity to the provisions on law enforcement and riot control: as a temporary effect from chemical action on the life processes (Article II, 1(2)) and in the motivation for listing particular compounds in each of the three Schedules.

The CWC, however, does define ‘riot control agent’ (Article II, 7), but, as already noted, without reference to incapacitation. Listed effects are sensory irritation and disabling physical effects which disappear within a short time following termination of exposure. So, if the time frame helps to narrow scope of toxic agents permissible for riot control purposes, what does the definition tell us about the use of incapacitants in law enforcement operations other than riot control (e.g., counter-terrorism)? Is there a legal definition of ‘incapacitating toxic agent’?

If we take the three specialised branches of law mentioned earlier together, we face some additional questions about who can deploy incapacitants and under what circumstances. In the case of internal or international war, would every type of use be considered a ‘method of warfare’? The use of tear gas to quell an uprising inside a POW camp comes to mind. The exemption adopted by the US Senate in its CWC ratification resolution authorising the use of tear gas in military rescue operations reaches deep into the legal understanding of ‘warfare’. Can the military use riot control agents and incapacitants if they are involved in non-military operations, e.g., law enforcement as part of a peace-keeping operation?

I plan to return to these questions in follow-on postings.