The United Nations Conference on the Law of Treaties, held in 1969 at Vienna, adopted a resolution entitled “Resolution relating to article 1 of the Vienna Convention on the Law of Treaties”, annexed to the Final Act, recommending that the General Assembly should refer to the Commission the study of the question of treaties concluded between States and international organizations or between two or more international organizations. Acting on this recommendation, the General Assembly, in resolution 2501 (XXIV) of 12 November 1969 (E, F, S, R, C, A), recommended that the International Law Commission should study the question, in consultation with the principal international organizations.

Extracts from The Work of the International Law Commission, 6th ed., vol. 1

At its twenty-second session, in 1970, the Commission included this question in its programme of work and set up a Subcommittee to consider the preliminary problems involved in the study of the topic. The Subcommittee’s report, [1]  as adopted by the Commission, requested the Secretariat to undertake certain preparatory work, in particular as regards United Nations practice, and asked the Chairman of the Subcommittee to submit to members of the Subcommittee a questionnaire concerning the method of treating the topic and its scope.

At the Commission’s twenty-third session, in 1971, the Subcommittee submitted to the Commission a report, [2]  containing a summary of the views expressed by members of the Subcommittee in reply to the questionnaire prepared by its Chairman, and recommendations to the Commission, in particular to appoint a Special Rapporteur for the topic and confirm the request addressed to the Secretary-General concerning certain preparatory work. The Commission considered the report and adopted it without change. At the same session, the Commission appointed Paul Reuter as Special Rapporteur for the topic.

The Commission considered the topic from its twenty-fifth to twenty-seventh and from its twenty-ninth to thirty-fourth sessions, from 1973 to 1975 and from 1977 to 1982, respectively. In connection with its consideration of the topic, the Commission had before it the reports of the Special Rapporteur, [3]  information provided by Governments and international organizations [4]  as well as documents prepared by the Secretariat. [5]

At its twenty-fifth session, in 1973, the Commission requested the Special Rapporteur to begin the preparation of a set of draft articles on the basis of his first two reports and the comments made during that session.

At its twenty-sixth session, in 1974, the Commission began the first reading of the draft articles, which was completed at its thirty-second session, in 1980. In accordance with the decision taken by the Commission at its thirtieth session, in 1978, the Commission, upon provisional adoption of certain sets of draft articles, transmitted them to Governments and principal international organizations [6]  for comments and observations, before the draft as a whole was adopted on the first reading. That procedure was seen as making it possible for the Commission to undertake the second reading without too much delay.

The General Assembly, in resolution 35/163 of 15 December 1980 (E, F, S, R, C, A), invited the Commission to commence the second reading of the draft articles.

The Commission proceeded with the second reading of the draft articles at its thirty-third and thirty-fourth sessions, in 1981 and 1982, respectively, in accordance with the General Assembly recommendation contained in resolution 36/114 of 10 December 1981 (E, F, S, R, C, A). At the latter session, the Commission adopted the final text of the draft articles, with commentaries, on the law of treaties between States and international organizations or between international organizations, and submitted it to the General Assembly with the recommendation that the Assembly convoke a conference to conclude a convention on the subject under article 23, subparagraph 1 (d) of its Statute. [7]

By resolution 37/112 of 16 December 1982 (E, F, S, R, C, A) , the General Assembly decided that an international convention should be concluded on the basis of the draft articles adopted by the Commission. In addition, the Assembly invited States and the principal international organizations to submit comments on the final draft as well as on other questions, such as the participation of international organizations in the conference and the solution of the problem of how international organizations would be associated with the convention.

At its thirty-eighth session, the General Assembly, by its resolution 38/139 of 19 December 1983 (E, F, S, R, C, A), decided that the appropriate forum for the final consideration of the draft articles was a conference of plenipotentiaries, to be convened not earlier than 1985. It also appealed to potential participants in the Conference to undertake consultations on the draft articles and related questions prior to the thirty-ninth session of the Assembly, in order to facilitate the successful conclusion of the work of the Conference. The following year the General Assembly, by resolution 39/86 of 13 December 1984 (E, F, S, R, C, A) , decided that the United Nations Conference on the Law of Treaties between States and International Organizations or between International Organizations would be held at Vienna from 18 February to 21 March 1986 and referred to the Conference as the basic proposal for its consideration the final set of draft articles adopted by the Commission at its thirty-fourth session, in 1982. It also appealed to participants in the Conference to organize consultations, primarily on the organization and methods of work of the Conference, including rules of procedure, and on major issues of substance, including final clauses and settlement of disputes, prior to the convening of the Conference in order to facilitate a successful conclusion of its work through the promotion of general agreement.

Informal consultations were held between 18 March and 1 May and between 8 and 12 July 1985. [8]  By resolution 40/76 of 11 December 1985 (E, F, S, R, C, A) , the General Assembly considered that those informal consultations proved useful in enabling thorough preparation for successful conduct of the Conference. The Assembly decided to transmit to the Conference, and to recommend that it adopt, the draft rules of procedure for the Conference, worked out during the informal consultations (annex I of the resolution). Also, the Assembly decided to transmit to the Conference for its consideration and action, as appropriate, a list of draft articles of the basic proposal, for which substantive consideration was deemed necessary (annex II of the resolution). Finally, the Assembly referred to the Conference for its consideration the draft final clauses presented by the co-Chairmen of the informal consultations on which an exchange of views had been held (annex III of the resolution).

The Conference was held at Vienna from 18 February to 21 March 1986. Ninety-seven States participated in the Conference, as did also Namibia, represented by the United Nations Council for Namibia. The Palestine Liberation Organization, the African National Congress of South Africa and the Pan Africanist Congress of Azania were represented by observers. Nineteen international intergovernmental organizations, including the United Nations, were represented at the Conference.

The Conference assigned to the Committee of the Whole those draft articles of the basic proposal which required substantive consideration as well as the preparation of the preamble and the final provisions of the Convention. It referred all other draft articles of the basic proposal directly to the Drafting Committee, which was furthermore responsible for considering the draft articles referred to it by the Committee of the Whole and for coordinating and reviewing the drafting of all texts adopted, as well as for the preparation of the Final Act of the Conference.

On 20 March 1986, the Conference adopted the Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations, [9]  which consists of a preamble, 86 articles and an annex.

The Convention applies to treaties between one or more States and one or more international organizations and to treaties between international organizations, the term “treaty” being defined for the purposes of the Convention as an international agreement governed by international law and concluded in written form between one or more States and one or more international organizations or between international organizations whether that agreement is embodied in a single instrument or in two or more related instruments and whatever its particular designation. The Convention does not apply to international agreements to which one or more States, one or more international organizations and one or more subjects of international law other than States or international organizations are parties, to international agreements to which one or more international organizations and one or more subjects of international law other than States or organizations are parties, to international agreements not in written form between one or more States and one or more international organizations, or between international organizations, or to international agreements between subjects of international law other than States or international organizations. That fact shall not affect (a) the legal force of such agreements; (b) the application to them of any of the rules set forth in the Convention to which they would be subject under international law independently of the Convention; or (c) the application of the Convention to the relations between States and international organizations or to the relations of organizations between themselves, where those relations are governed by international agreements to which other subjects of international law are also parties.

The principal matters covered in the Convention are: conclusion and entry into force of treaties (part II); observance, application and interpretation of treaties (part III); amendment and modification of treaties (part IV); invalidity, termination and suspension of the operation of treaties (part V); miscellaneous provisions (part VI), dealing, inter alia, with the relationship of the Convention to the Vienna Convention on the Law of Treaties and reserving questions that may arise in regard to a treaty from a succession of States, from the international responsibility of a State or from the outbreak of hostilities between States, from the international responsibility of an international organization, from the termination of the existence of the organization or from the termination of participation by a State in the membership of the organization, as well as questions that may arise in regard to the establishment of obligations and rights for States members of an international organization under a treaty to which that organization is a party; and depositaries, notifications, corrections and registration (part VII). The procedures for judicial settlement, arbitration and conciliation referred to in article 66 of the Convention are specified in an annex to the Convention.

On 21 March 1986, the Convention was opened for signature, by all States, Namibia, represented by the United Nations Council for Namibia, and international organizations invited to participate in the Conference. [10]  It remained open for signature until 31 December 1986 at the Federal Ministry for Foreign Affairs of the Republic of Austria and, subsequently, until 30 June 1987 at United Nations Headquarters. The Convention is subject to ratification by States and to acts of formal confirmation by international organizations. The Convention remains open for accession by any State and by any international organization which has the capacity to conclude treaties. The Convention shall enter into force on the thirtieth day following the date of deposit of the thirty-fifth instrument of ratification or accession by a State. By 4 November 2003, twenty-sixth States had deposited instruments of ratification, accession or succession. [11]

In addition to the Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations, the Conference adopted five resolutions which were annexed to the Final Act of the Conference. [12]  In accordance with one of the resolutions, the expenses of any arbitral tribunal and conciliation commission that may be set up under article 66 of the Convention shall be borne by the United Nations.

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