Attempts to prohibit the use of chemical weapons began with the Strasbourg Agreement (1675), a bilateral French-German accord which prohibited the use of poison bullets. The first multilateral accord to target chemical weapons was the Brussels Declaration (1874). The Hague Gas Declaration of 1899 (stemming from the Hague Peace Conference of that year) banned " the use of projectiles, the sole object of which is the diffusion of asphyxiating or deleterious gases" . A second Hague Conference, held in 1907, went even further: under Convention IV (entitled " Respecting the Laws and Customs of War on Land" ), Article 23 of the attached Annex prohibited the use of poisonous weapons. However, a number of participants felt that this prohibition did not extend to gas weapons, given that the issue of gas weapons was dealt with in the Hague Gas Declaration. In 1919, following the end of the First World War, the Allies and the Central Powers signed the Versailles Treaty. Article 171 stated that " the use of asphyxiating, poisonous or other gases and all analogous liquids, materials or devices being prohibited, their manufacture and importation are strictly forbidden in Germany" ; it went on to say that " the same applies to materials specially intended for the manufacture, storage and use of the said products or devices" . Although, the United States government did not sign the Treaty, American domestic public opinion began to press for some broader action on the issue of controlling these weapons. Finally, in February of 1922, the United States, the British Empire, France, Italy and Japan signed the Washington Treaty on Use of Submarines and Gases in Wartime (otherwise known as the Washington Treaty). Under Article V of the Treaty, the signatories prohibited the use of chemical weapons.
Given the strong public sentiment concerning the horrors of the First World War, the League of Nations undertook another negotiation on the subject of chemical warfare in 1924. In June of 1925, the conference participants approved the Geneva Protocol, which banned the use of chemical and bacteriological weapons (but not their development or possession) and played a crucial role in nurturing the growth of the international norm that chemical weapons were an unacceptable instrument of warfare. At the time, forty-one states signed the Protocol, with most ratifying it. (There are now 133 States Parties to the Geneva Protocol). Still, a number of signatories - including Canada - expressed a reservation concerning this document, stating that the provisions of the Protocol only banned the first use of such weapons: they maintained that states would be justified in using them in a retaliatory capacity. (The Government of Canada removed this reservation to the Protocol in October 1999.) The Protocol was also hindered by the lack of any capacity for sanctions, verification or enforcement. This would frustrate supporters of chemical weapons arms control in the period before the Second World War, and lead many to claim that the Protocol's real authority was moral rather than legal.
Following the Second World War, the issue of chemical weapons control became increasingly subsumed within the agenda on " weapons of mass destruction" , alongside nuclear and biological weapons. In a September 1961 Statement of Agreed Principles, the American and Soviet governments made it clear that they would consider the disarmament of chemical weapons in tandem with their nuclear and biological counterparts, through an agreed-upon sequential and verifiable process carried out under the rubric of an " International Disarmament Organization" . The UN Eighteen-Nation Conference on Disarmament subsequently became the forum for these talks (it was subsumed by the Committee on Disarmament in 1969, which was subsequently renamed the Conference on Disarmament (CD) in 1979). However, both the Warsaw Pact and NATO developed considerable stockpiles of chemical weapons during the Cold War, as did a number of other nations throughout the world. The CD talks reached their nadir in 1979, when the American government halted its participation in the face of what it considered Soviet non-compliance and disinterest in the norms of chemical weapons disarmament.
In 1984, the American administration presented a new draft treaty at the CD. Comprising eighteen articles, it emphasized the need to clarify definitions, the terms of verification and compliance, and the activities which would be permitted under the Treaty. Furthermore, it went on to explore the issue of administrative structure so crucial to treaty implementation. Despite the difficult negotiations which would follow during the next several years, these key concepts would remain central to what would become the Chemical Weapons Convention (CWC). The CWC, which was opened for signature in January 1993 and entered into force in April 1997, currently has 184 States Parties. The Convention provides extensive, detailed verification measures - including declarations and on-site inspections - to support its basic prohibition of all chemical weapons. The international implementation of the CWC is overseen by the Organization for the Prohibition of Chemical Weapons (OPCW), located in The Hague, Netherlands.