The Conference of the States Parties is the plenary organ consisting of all members of the OPCW. It is the "principal organ of the Organisation", and has the general power to oversee the implementation of the Convention, and to act in order to promote the object and purpose of the Convention.

In this regard, the Conference may make recommendations and take decisions on any questions, matters, or issues within the scope of the Convention. The Conference oversees the activities of the Council and the Secretariat, and may issue guidelines in accordance with the Convention to either of them in the exercise of their functions.

The specific activities to be undertaken by the Conference are listed in Article VIII, paragraph 21, and include:

• taking measures necessary to ensure compliance with the Convention;
• deciding on the programme and budget and the scale of financial contributions to be paid by States Parties;
• approving the annual report of the Organisation;
• electing the members of the Council;
• appointing the Director-General;
• fostering international cooperation for peaceful purposes in the field of chemical activities; and
• reviewing scientific and technological developments that could affect the Convention. 

Decision making

A majority of members of the Organisation constitutes a quorum for sessions of the Conference. Each member has one vote.

The Conference takes decisions on questions of procedure by a simple majority of members present and voting. Substantive decisions should, if possible, be taken by consensus. If consensus is not attainable, a 24-hour period of deferment is called by the Chairman of the Conference and every effort is made to facilitate consensus.

If this procedure is not successful, the Conference may take a decision by a two-thirds majority of members present and voting. If the issue arises as to whether or not a question is one of substance, that question is to be treated as a matter of substance, unless the Conference decides otherwise by the majority required for decisions on matters of substance.

So far, the majority of Conference decisions have been taken by consensus.

Subsidiary bodies

The Convention requires the Conference to establish two subsidiary bodies: the Commission for the Settlement of Disputes related to Confidentiality (the "Confidentiality Commission") and the Scientific Advisory Board.

In addition to these two Convention-mandated subsidiary bodies, the Conference is authorised to establish such subsidiary organs as it finds necessary for the exercise of its functions (Article VIII, subparagraph 21(f)). On the basis of this authority the Conference has established several committees.

Under its rules of procedure, the Conference appoints at each session a General Committee which addresses administrative/organisational issues such as the provisional agenda for the session, requests for additional items, the establishment of committees and the allocation of tasks to them.

Committee of the Whole

At each regular session, the Conference also elects the chairperson of its main committee, the Committee of the Whole. The Committee of the Whole serves as the forum for the discussion of issues which, in the estimation of the Conference, are not yet ripe for decision-making, and which accordingly require consultations and discussion involving all members in attendance at the session.

If the Committee of the Whole is able to resolve such issues, it makes recommendations for action to the Conference. In the first years of the OPCW's existence the Committee of the Whole continued to function between sessions of the Conference to consider unresolved issues.

In 1999, however, the Conference transferred all unresolved issues that had hitherto been the province of the Committee of the Whole to the Council, for consideration by the Council's working groups, which are open to all Member States.

The functioning of the Committee of the Whole as the principal intersessional forum for the resolution of unresolved issues thus came to an end, although its role during sessions of the Conference remained unchanged. Intersessional work on unresolved issues has become the ongoing responsibility of the Council, with the participation of all Member States.

Credentials Committee

In addition, the Credentials Committee is appointed at the beginning of each session of the Conference, at the proposal of the Chairman of the Conference. The Credentials Committee, which consists of ten members, is required to examine the credentials of all representatives to that Conference session. Pending a decision of the Committee on their credentials, representatives are entitled to participate provisionally in the session.

Any representative to whom another member of the OPCW has objected is seated provisionally with the same rights as other representatives until the Committee has reported, and the Conference has taken a decision on the objection.