The Biological Weapons Convention

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The scope, strengths, and weaknesses of the Biological Weapons Convention (BWC)


Biological weapons are subject to the strongest ban among weapons of mass destruction under international law. The main legal instrument addressing biological weapons, the Biological Weapons Convention (BWC), essentially bans the weaponization of biology. 

The convention does not explicitly prohibit use, but targets instead the activity prior to use—reliance on biology as a weapon in the sense of stockpiling, acquiring biological agents or toxins intended for a certain type of use, or development of platforms designed for dispersing biological agents or toxins.

Status of the treaty

As of 2015, the BWC has a total of 171 States Parties. This means that as many as 25 UN member and observer states have yet to ratify the convention. 9 of these have signed the treaty and are thus ‘obliged to refrain from acts which would defeat the object and purpose of a treaty’,[1] while the remaining 16 states have neither signed nor ratified the treaty (see map for details).[2]

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The BWC was negotiated in 1972, and was the first convention ever that totally banned an entire class of weapons.[3] The convention is far simpler and less sophisticated than subsequent arms ban treaties. A few key provisions stipulate prohibitions, measures of implementation and protection of peaceful use.

While the simplicity of the BWC may offer flexibility, a less benign effect is the unclear scope of the treaty. In order to address this weakness, the BWC contains a general review clause. State parties may adapt and develop the treaty by way of review conferences organized every 5 years without having to resort to a formal modification procedure.

The provisions of the BWC essentially express four principles:

  • The prohibition to acquire or retain biological or toxin weapons;
  • The prohibition to assist others to acquire such weapons;
  • The obligation to take necessary measures to ensure that such weapons are prohibited at a domestic level;
  • And finally the commitment to ensure that peaceful use of biological science and technology may nevertheless develop.

While the BWC does not explicitly prohibit use of biological weapons, the review conference in 1996 affirmed that “the use by parties […of] biological agents or toxins, that is not consistent with prophylactic, protective or other peaceful purposes, is effectively a violation of Article I of the convention”.[4] The use of bacteriological weapons is also prohibited under the 1925 Geneva Gas Protocol, a protocol that enjoys the status of custom and is therefore binding on all states irrespective of ratification.[5]

The idea behind the BWC has repeatedly been expressed as “what is not possessed, cannot be used”.[6] In 2006, state parties unanimously confirmed that the convention prohibits use of bioweapons by anyone, anywhere, at any time and for any purpose.[7] An understanding was also reached that even individuals are covered by the convention’s prohibitions. The BWC is hence understood to prohibit weaponization of biology or use of biological weapons by international actors, states, sub-national entities and individuals. Its scope unambiguously extends to all relevant actors involved with existing pathogens, chimera and synthetic biology.

Strengths and weaknesses

The flexible nature of the convention is an advantage in light of adapting the BWC to novel technologies. BWC article I states that all agents and toxins are covered, regardless of “origin or method of production”. Implicitly, changes in the means of producing biological weapons are already covered by the convention, and new scientific and technological developments are explicitly stipulated as elements to take into account in review conferences (Art. XII). A less benign effect of broad strokes in a convention is the uncertainties and cracks that may arise at its edges.

A key component of the BWC is that it bans the development, production, or possession of an entire class of weapons unconditionally – thereby in all circumstances. The BWC contains no exception for weapons intended for specific purposes or assignments short of armed conflict. It prohibits any weaponization of disease agents or germs, irrespective of context or effects, earning the ban a label as categorical. The absence of intended lethality does not influence the lawfulness of a weapon under the BWC. The prohibition therefore also extends to non-lethal weapons, such as biologically engineered microbes that could attack an enemy’s food or fuel, or germs that could corrupt enemy vehicle tires or belts.[1]

While the BWC does not define biological weapons, it circumscribes its prohibitions by a general-purpose criterion. Only agents and toxins in types and quantities that have “no justification for prophylactic, protective or other peaceful purposes” are banned. During the negotiations of the convention it was clarified that “prophylactic” encompasses medical activities such as diagnosis, therapy and immunization, whereas “protective” covers the development of protective equipment and warning devices. It must not be interpreted as permitting possession of biological agents and toxins for defence, retaliation or deterrence.[8]

While the ban on biological weapons is absolute, the prohibition’s combination of purpose with type and quantity leaves room for numerous activities with germs that may easily be turned into weapons.

Moreover, the mechanisms to enforce the multi-layered prohibition are comparatively weak. Importantly, the BWC does not establish an organization tasked with verification and enforcement of the treaty similar to the Non-Proliferation Treaty (the IAEA) or the CWC (the OPCW).

The BWC requires the complete destruction of all bioweapons and no future production, but it does not establish an independent intergovernmental institution tasked with overseeing and enforcing that process.[9]

States may lodge a complaint before the UN Security Council under article VI. Measures to ensure respect for the convention beyond this essentially boils down to a set of unbinding confidence building measures and criminalisation at the national level. Each State party to the BWC is also required to designate a domestic agency to be responsible for guaranteeing compliance with the treaty’s provisions. But the treaty is essentially based on self-verification.

The irony is that while biological weapons are subject to the strongest and most categorical ban among the weapons of mass destruction—and arguably of any class of weapons—this ban suffers from the weakest mechanisms of verification and enforcement.



[1] Koplow, David, “Death by Moderation”, Cambridge University Press, 2010 p. 208.

[2] See for the status of the BWC. The following 9 states have signed but not ratified the BWC: Central African Republic, Côte d’Ivoire, Egypt, Haiti, Liberia, Nepal, Somalia, Syrian Arab Republic, United Republic of Tanzania. The following 16 states have neither signed nor ratified the BWC: Angola, Chad, Comoros, Djibouti, Dominica, Eritrea, Guinea, Israel, Kiribati, Micronesia, Namibia, Niue, Palestine, Samoa, South Sudan, Tuvalu, Vanuatu.

[3] For a detailed analysis of the Convention legal regime, see Stein, E ”Impacts of New Weapons Technology on International Law” 133 Recueil des Cours de l’Academie de Droit International de la Haye (1971 II) p. 223-388.

[4] Fourth Review Conference, 25-6 Dec 1996, Final Declaration, BWC/CONF.IV/9 Part II.

[5] International Committee of the Red Cross (2005). Customary International Humanitarian Law, Volume I: Rules, eds Henckaerts, Jean-Marie, Doswald-Beck, Louise. Cambridge University Press, p. 257.

[6] Lowe, A.V, W1972 Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and Their Destruction” The Law of Naval Warfare; A Collection of Agreements and Documents with Commentaries, 623,643 (N. Ronzitti, ed. 1988);  International Committee of the Red Cross (2005). Customary International Humanitarian Law, Volume I: Rules, eds Henckaerts, Jean-Marie, Doswald-Beck, Louise. Cambridge University Press, p. 257

[7] Sixth Review Conference of the States Parties to the BWC, Geneva Switz., Nov. 2–Dec. 8, 2006, Final Document, at 9, U.N. Doc. BWC/CONF.VI/6, article I(2) (2006)

[8] Goldblat, Jozef, “The Biological Weapons Conventions: An Overview”, 37 International Review of the Red Cross,( 1997) p. 251 at 257.

[9] Nicholas A. Sims, “The Evolution of Biological Disarmament,” SIPRI Chemical and Biological Warfare Studies, No. 19 (2001), pp. 82-118.