Vienna Convention on Succession of States in Respect of Treaties
Vienna, 23 August 1978
  •  Introductory Note 
  •  Procedural History 
  •  Documents 
  •  Status 
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By Anthony Aust
British Diplomatic Service (1967-2002), retiring as Deputy Legal Adviser
Legal Adviser (Counsellor) to the United Kingdom Mission to the United Nations in New York,
1988-1991

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In 1967, the International Law Commission (‘the Commission’) began work on the subject of succession of States in respect of treaties. In 1974, the Commission submitted to the United Nations General Assembly a final set of draft articles on Succession of States in respect of Treaties with a recommendation that the Assembly should convene a conference of plenipotentiaries to study the draft articles and conclude a convention on the subject. The General Assembly adopted resolutions 3496 (XXX) of 15 December 1975 and 31/18 of 24 November 1976 to this effect by which it accordingly decided that the draft articles should be considered by a United Nations Conference on Succession of States in respect of Treaties (‘the Conference’) to be held at Vienna from 4 April to 6 May 1997.

The Conference was held as scheduled but partly because the draft articles raised some controversial issues it recommended that the General Assembly decide to reconvene the Conference in the first half of 1978 for a final session. The resumed session of the Conference, approved by General Assembly resolution 32/47 of 8 December 1981, was held at Vienna from 31 July to 23 August 1978 and resulted in the adoption of the 1978 Vienna Convention on Succession of States in respect of Treaties (‘the 1978 Convention’).

Given the subject matter, there was no question of the 1978 Convention being based on the very successful 1969 Vienna Convention on the Law of Treaties (‘the 1969 Convention’). Instead, the Commission decided to deal with the subject as a question of succession. However, in appointing Sir Humphrey Waldock as the first Special Rapporteur (he had previously been its Special Rapporteur for the law of treaties), the Commission’s method of work would follow the pattern set by the elaboration of the draft articles on the law of treaties which eventually became the 1969 Convention. In 1973, Sir Francis Vallat succeeded Waldock for the last year of the Commission’s work on the subject.

The 1978 Convention did not enter into force until 1996 when it achieved the necessary fifteen expressions of consent to be bound. This was almost eighteen years after its adoption. Entry into force only happened because, between 1991 and 1996, Bosnia and Herzegovina, Croatia, Estonia, Slovakia, Slovenia, the former Yugoslav Republic of Macedonia and Ukraine acceded or succeeded to the 1978 Convention. Not surprisingly, as new States they presumably thought it would be useful to them. Estonia is included as a new State even though it resumed its previous statehood. However, since it had been for fifty years de facto part of the Soviet Union, it had to resolve succession problems of some novelty. Although Byelorussia (now Belarus) and Ukraine had been part of the Soviet Union, as the result of a political deal involving also India (which became independent only in 1947) all three became founding Members of the United Nations. Yet, the former Soviet republics also had their own succession problems (on the particular treaty succession problems of Estonia, and Belarus and Ukraine, see A. Aust, Modern Treaty Law and Practice, 2nd ed., Cambridge, Cambridge University Press, 2007, pp. 377-8 and 376-7, respectively). Today, the 1978 Convention has but twenty-two parties, the most recent being the Republic of Moldova. So, why has the 1978 Convention not been more successful?

The so-called Cold War was still an important factor when the 1978 Convention was adopted. As a consequence, some of the draft articles were adopted by separate votes. In addition, there was no general doctrine which resolved the problems of succession to treaties. In particular, the situations in which new States are created vary enormously, and a “one-size fits all” approach was quite unsuitable. The number of different theories of succession did not make the task of devising a text on the subject any easier. As a result, the 1978 Convention contains much that is contentious progressive development of international law. When the Commission was developing its draft articles (in the relatively short space of seven years) the most recent State practice related to former colonies but was not consistent. Consequently, those rules of the 1978 Convention which are concerned with newly independent States are excessively complex. They also give undue prominence to the so-called “clean slate” principle, and not enough weight to the abundant State practice of concluding devolution agreements or, even more importantly, making declarations of succession. Moreover, decolonisation was almost at its end by 1978, and, unless a successor State agrees otherwise, the 1978 Convention does not apply to a succession of States which occurs before its entry into force (6 November 1996).

Nor did the 1978 Convention’s rules about the break-up of States reflect modern State practice, in particular the great variety of situations occurring at the end of the twentieth century. The reunification of Germany took place in 1990. The break-up of the Soviet Union occurred in 1991, and of Yugoslavia mainly between 1992 and 1993. The so-called velvet divorce of Czechoslovakia happened in 1993. In short, before the 1990s there was little of recent practice on which to draw.

Although parts of the 1978 Convention may have been relied upon in drafting certain bilateral succession agreements – an example in point being the strong endorsement of article 34(1) (Succession of States in cases of separation of parts of a State) in the practices of the successor States to the former Czechoslovakia – its influence and practical value is likely to continue to be considerably less than that of the 1969 Convention. Notwithstanding the reference by the Arbitration Commission of the Conference for Peace in Yugoslavia (also known as the ‘Badinter Commission’) in its Opinions Nos. 1 and 9 to the 1978 Convention as embodying principles of international law, article 34 cannot necessarily be taken as reflecting customary international law.

Although the 1978 Convention is an example of progressive development of international law, the customary rules of international law on succession of States in respect of treaties apply to most States, yet they are not reflected in the text of the 1978 Convention. Therefore, it is not a reliable guide to such rules of customary law on treaty succession. Yet, albeit its late entry into force, practice following the end of the Cold War and decisions of the International Court of Justice may now have breathed a little life into a few of its provisions (see Application of the Genocide Convention (Bosnia and Herzegovina v. Yugoslavia), I.C.J. Reports 1996, pp. 595 and 611-12 and Gabčíkovo-Nagymaros Project (Hungary/Slovakia), I.C.J. Reports 1997, pp. 7 and 72). But, they are unlikely to result in many States wanting now to be parties to the 1978 Convention. So, it may remain little more than an interesting historical document.


Related Materials

A. Jurisprudence

Arbitration Commission of the Conference for Peace in Yugoslavia (‘Badinter Commission’), Opinion No. 1 on Questions Arising from the Dissolution of Yugoslavia (reproduced in International Legal Materials, vol. 31 (1992), p. 1497).

Arbitration Commission of the Conference for Peace in Yugoslavia (‘Badinter Commission’), Opinion No. 9 on Questions Arising from the Dissolution of Yugoslavia (reproduced in International Legal Materials, vol. 31 (1992), p. 1523).

International Court of Justice, Application of the Convention on the Prevention and Punishment of the Crime of Genocide, Preliminary Objections, (Bosnia and Herzegovina v. Yugoslavia) Judgment, I.C.J. Reports 1996, p. 595.

International Court of Justice, Gabčíkovo-Nagymaros Project (Hungary/Slovakia), Judgment, I.C.J. Reports 1997, p. 7.

B. Documents

Report of the International Law Commission on the work of its twenty-sixth session, 6 May - 26 July 1974, Official Records of the General Assembly, Twenty-ninth session, Supplement No. 10 (A/9610/Rev.1, reproduced in Yearbook of the International Law Commission, 1974, vol. II (Part One), chapter II).

General Assembly resolution 3496 (XXX) of 15 December 1975 (Succession of States in respect of treaties).

General Assembly resolution 31/18 of 24 November 1976 (United Nations Conference on Succession of States in respect of Treaties).

General Assembly resolution 32/47 of 8 December 1977 (United Nations Conference on Succession of States in respect of Treaties).

United Nations Conference on Succession of States in Respect of Treaties, First Session, Vienna, 4 April - 6 May 1977, Official Records,Vol. I: Summary records of the plenary meetings and of the meetings of the Committee of the Whole (A/CONF.80/16).

United Nations Conference on Succession of States in Respect of Treaties, Resumed Session, Vienna, 31 July - 23 August 1978, Official Records,Vol. II: Summary records of the plenary meetings and of the meetings of the Committee of the Whole (A/CONF.80/16/Add.1).

United Nations Conference on Succession of States in Respect of Treaties, 1977 session and resumed session 1978, Vienna, 4 April - 6 May 1977 and 31 July - 23 August 1978, Official Records, Vol. III: Documents of the Conference (A/CONF.80/16/Add.2).

C. Doctrine

A. Aust, Modern Treaty Law and Practice, 2nd ed., Cambridge, Cambridge University Press, 2007, pp. 367-391.

D. P. O’Connell, The Law of State Succession, Cambridge, Cambridge University Press, 1956.

J. Klabbers, M. Koskenniemi, O. Ribbelink and A. Zimmermann (eds.), State Practice Regarding State Succession and Issues of Recognition: the Pilot Project of the Council of Europe, (on behalf of Erik Castrén Institute of International law and Human Rights, Finland, T.M.C. Asser Institute, The Netherlands, Max Planck Institute for Comparative Public Law and International Law, Germany), The Hague, London, Boston, Kluwer Law International, 1999.

M. Shaw, International Law, 6th ed., Cambridge, Cambridge University Press, 2008, pp. 966-984.

A. Watts, The International Law Commission 1949-1998, vol. II, Oxford, Oxford University Press, 2000, p. 987 et seq.


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At its first session, in 1949, the International Law Commission selected the subject of succession of States and Governments as one of the topics for codification without, however, including it in the list of topics to which it gave priority. At its fourteenth session, in 1962, the Commission was apprised of General Assembly resolution 1686 (XVI) of 18 December 1961, recommending that the Commission include on its priority list the topic of succession of States and Governments. The Commission decided to set up a Subcommittee on the Succession of States and Governments whose task was to submit to the Commission a preliminary report containing suggestions on the scope of the subject, the method of approach to the study and the means of providing the necessary documentation (A/CN.4/149 and Add.1, A/CN.4/150 and A/CN.4/151). At its fifteenth session, in 1963, the Commission considered and unanimously approved the report of the Subcommittee (A/5509).

7 November 1974, Twenty-ninth Session of the General Assembly at which the debate continued in the Sixth Committee on the report of the International Law Commission containing draft articles on succession of States in respect of treaties, United Nations Headquarters, New York: general view of the Committee in session.The Commission expressed its agreement with the broad outline, the order of priority of the headings and the detailed division of the topic recommended by the Subcommittee: succession in respect of treaties; succession in respect of rights and duties resulting from other sources than treaties (revised in 1968 to read “succession of States in respect of matters other than treaties”) and succession in respect of membership of international organizations. The Commission approved the Subcommittee’s recommendations concerning the relationship between the topic of State succession and other topics on the Commission’s agenda, in particular that the succession in respect of treaties would be considered in connection with the succession of States rather than in the context of the law of treaties. The Commission appointed Mr. Manfred Lachs as Special Rapporteur for the topic.

Following the resignation of Mr. Lachs, the Commission decided, at its nineteenth session, in 1967, to deal with the three aspects of the topic in accordance with the broad outline of the subject laid down in the report of the Subcommittee in 1963. The Commission appointed Special Rapporteurs for the first two aspects of the topic, succession in respect of treaties and succession of States in respect of matters other than treaties.

The Commission considered the sub-topic of succession of States in respect of treaties at its twentieth, twenty-second, twenty-fourth and twenty-sixth sessions, in 1968, 1970, 1972 and 1974, respectively. The Commission appointed Sir Humphrey Waldock and Sir Francis Vallat as the successive Special Rapporteurs for the sub-topic at its nineteenth and twenty-fifth sessions, in 1967 and 1973, respectively. In connection with its consideration of the topic, the Commission had before it the reports of the Special Rapporteurs, information provided by Governments and international organizations as well as documents prepared by the Secretariat.

At its twenty-fourth session, in 1972, the Commission conducted the first reading of the draft articles on succession of States in respect of treaties. At that session, the Commission adopted on first reading a provisional draft with commentaries and, in accordance with articles 16 and 21 of its Statute, decided to transmit it to Governments of Member States for their observations.

The General Assembly, in resolution 2926 (XXVII) of 28 November 1972, recommended that the Commission should continue its work on the sub-topic in the light of comments received from Member States on the provisional draft. In resolution 3071 (XXVIII) of 30 November 1973, the General Assembly recommended that the Commission complete at its twenty-sixth session, in 1974, the second reading of the draft on succession of States in respect of treaties, in the light of comments received from Member States.

At its twenty-sixth session, in 1974, the Commission adopted the final text of the draft articles on the succession of States in respect of treaties, with commentaries (A/9610/Rev.1) and submitted it to the General Assembly with a recommendation that the General Assembly should invite Member States to submit their written comments and observations on the draft articles and should convene a conference of plenipotentiaries to study the draft articles and conclude a convention on the subject (A/9610/Rev.1).

The General Assembly, in resolution 3315 (XXIX) of 14 December 1974, invited Member States to submit their written comments and observations on the draft articles prepared by the Commission and on the procedure by which and the form in which work on the draft articles should be completed. The following year, the Assembly, by resolution 3496 (XXX) of 15 December 1975, decided to convene a conference of plenipotentiaries in 1977 to consider the draft articles and to embody the results of its work in an international convention and such other instruments as it might deem appropriate. In the resolution, the General Assembly urged Member States which had not yet done so to submit as soon as possible their written comments and observations on the draft articles. On 24 November 1976, the General Assembly adopted resolution 31/18 by which it decided that the United Nations Conference on Succession of States in Respect of Treaties would be held from 4 April to 6 May 1977 at Vienna.

The Conference was held as scheduled but, having been unable to conclude its work in the time available; it recommended on 6 May 1977 that the General Assembly decide to reconvene the Conference in the first half of 1978 for a final session (A/CONF.80/15).

The resumed session of the Conference, approved by General Assembly resolution 32/47 of 8 December 1977, was held at Vienna from 31 July to 23 August 1978.

The delegations of one hundred States participated in the Conference (eighty-nine States in the 1977 session and ninety-four States in the resumed session). On 22 August 1978, the Conference adopted the Vienna Convention on Succession of States in Respect of Treaties consisting of a preamble, fifty articles and an annex.

The Final Act of the Conference, of which five resolutions adopted by the Conference form an integral part, was signed on 23 August 1978. The Convention was opened for signature on 23 August 1978 and remained open for signature until 31 August 1979 at United Nations Headquarters in New York. The Convention entered into force on 6 November 1996.


Text of the Convention

Selected preparatory documents
(in chronological order)

General Assembly resolution 1686 (XVI) of 18 December 1961 (Future work in the field of the codification and progressive development of international law)

International Law Commission, Memorandum prepared by the Secretariat: “The succession of States in relation to membership in the United Nations” (A/CN.4/149 and Add.1, 3 December 1962, reproduced in Yearbook of the International Law Commission, 1962, vol. II)

International Law Commission, Study prepared by the Secretariat: “Digest of the decisions of international tribunals relating to State succession” (A/CN.4/151, 3 December 1962, reproduced in Yearbook of the International Law Commission, 1962, vol. II)

International Law Commission, Memorandum prepared by the Secretariat: “Succession of States in relation to general multilateral treaties of which the Secretary-General is the depositary” (A/CN.4/150, 10 December 1962, reproduced in Yearbook of the International Law Commission, 1962, vol. II)

International Law Commission, Study prepared by the Secretariat: “Digest of decisions of national courts relating to succession of States and Governments” (A/CN.4/157, 18 April 1963, reproduced in Yearbook of the International Law Commission, 1963, vol. II, document A/5509, annex II)

International Law Commission, Report on the succession of States and Governments, prepared by Mr. Manfred Lachs (A/CN.4/160 and Corr. 1, 7 June 1963, reproduced in A/5509, Yearbook of the International Law Commission, 1963, vol. II)

International Law Commission, Studies prepared by the Secretariat: “Succession of States to multilateral treaties” (A/CN.4/200 and Corr.1 and Adds.1-2, 21 February, 15 March and 23 April 1968, reproduced in Yearbook of the International Law Commission, 1968, vol. II)

International Law Commission, First report on succession of States and Governments in respect of treaties,  prepared by the Special Rapporteur, Sir Humphrey Waldock (A/CN.4/202, 15 March 1968, reproduced in A/7209/Rev.1, Yearbook of the International Law Commission, 1968, vol. II)

International Law Commission, Sixth study prepared by the Secretariat: “Succession of States to multilateral treaties” (A/CN.4/210, 11 June 1968, reproduced in Yearbook of the International Law Commission, 1969, vol. II)

Report of the International Law Commission on the work of its twentieth session (A/7209/Rev.1, reproduced in Yearbook of the International Law Commission, 1968, vol. II)

International Law Commission, Second report on succession in respect of treaties, prepared by the Special Rapporteur, Sir Humphrey Waldock (A/CN.4/214 and Adds.1 and 2, 18 April, 9 June and 22 July 1969,reproduced in A/8010/Rev.1, Yearbook of the International Law Commission, 1969, vol. II)

Report of the International Law Commission on the work of its twenty-first session (A/7610/Rev.1, reproduced in Yearbook of the International Law Commission, 1969, vol. II)

International Law Commission, Supplement prepared by the Secretariat: “Digest of the decisions of international tribunals relating to State succession” (A/CN.4/232, 7 April 1970, reproduced in A/8010/Rev.1, Yearbook of the International Law Commission, 1970, vol. II)

International Law Commission, Seventh study prepared by the Secretariat: “Succession of States to multilateral treaties” (A/CN.4/225, 24 April 1970, reproduced in A/8010/Rev.1, Yearbook of the International Law Commission, 1970, vol. II)

International Law Commission, Third report on succession in respect of treaties, prepared by the Special Rapporteur, Sir Humphrey Waldock (A/CN.4/224 and Add.1, 22 April and 27 May 1970, reproduced in A/8010/Rev.1, Yearbook of the International Law Commission, 1970, vol. II)

International Law Commission, Study prepared by the Secretariat: “Succession of States in respect of bilateral treaties” (A/CN.4/229, 28 May 1970, reproduced in A/8010/Rev.1, Yearbook of the International Law Commission, 1970, vol. II)

Report of the International Law Commission on the work of its twenty-second session (A/8010/Rev.1, reproduced in Yearbook of the International Law Commission, 1970, vol. II)

International Law Commission, Second and third studies prepared by the Secretariat: “Succession of States in respect of bilateral treaties” (A/CN.4/243 and Add.1, 9 April and 24 March 1971, reproduced in A/8410/Rev.1, Yearbook of the International Law Commission, 1971, vol. II (Part Two))

International Law Commission, Fourth report on succession in respect of treaties, prepared by the Special Rapporteur, Sir Humphrey Waldock (A/CN.4/249, 24 June 1971, reproduced in A/8410/Rev.1, Yearbook of the International Law Commission, 1971, vol. II (Part One))

Report of the International Law Commission on the work of its twenty-third session (A/8410/Rev.1, reproduced in Yearbook of the International Law Commission, 1971, vol. II (Part One))

International Law Commission, Supplement prepared by the Secretariat to “Materials on Succession of States” (A/CN.4/263, 29 May 1972, reproduced in A/8710/Rev.1)

International Law Commission, Fifth report on succession in respect of treaties, prepared by the Special Rapporteur, Sir Humphrey Waldock (A/CN.4/256 and Adds.1–4, 10 April, 29 May and 8, 16 and 28 June 1972, reproduced in A/8710/Rev.1, Yearbook of the International Law Commission, 1972, vol. II)

International Law Commission, Draft articles on succession in respect of treaties: general article submitted by the Special Rapporteur as a possible means of covering the question of lawfulness (A/CN.4/L.184, 12 June 1972, reproduced in Yearbook of the International Law Commission, 1972, vol. II)

Report of the International Law Commission on the work of its twenty-fourth session, 2 May to 7 July 1972 (A/8710/Rev.1, reproduced in Yearbook of the International Law Commission, 1972, vol. II)

Report of the International Law Commission on the work of its twenty-fifth session, 7 May to 13 July 1973 (A/9010/Rev.1, reproduced in Yearbook of the International Law Commission, 1973, vol. II)

International Law Commission, First report on succession of States in respect of treaties, prepared by the Special Rapporteur, Sir Francis Vallat (A/CN.4/278 and Adds.1–6,19 and 22 April, 8, 24 and 31 May and 10 and 21 June 1974, reproduced in A/9610/Rev.1, Yearbook of the International Law Commission, 1974, vol. II (Part One))

International Law Commission, Observations of Member States on the draft articles on succession of States in respect of treaties adopted by the Commission at its twenty-fourth session, (A/CN.4/275 and Adds.1-2, reproduced in A/9610/Rev.1, Yearbook of the International Law Commission, 1974, vol. II (Part One))

Report of the International Law Commission on the work of its twenty-sixth session, 6 May to 26 July 1974 (A/9610/Rev.1, reproduced in Yearbook of the International Law Commission, 1974, vol. II (Part One))

General Assembly resolution 3496 (XXX) of 15 December 1975 (Succession of States in respect of treaties)

General Assembly resolution 31/18 of 24 November 1976 (United Nations Conference on Succession of States in Respect of Treaties)

General Assembly resolution 32/47 of 8 December 1977 (United Nations Conference on Succession of States in Respect of Treaties)


The Convention entered into force on 6 November 1996. For the current participation status of the Convention, as well as information and relevant texts of related treaty actions, such as reservations, declarations, objections, denunciations and notifications, see:

The Status of Multilateral Treaties Deposited with the Secretary-General

6 May 1974, Twenty-sixth Session of the International Law Commission at which the Commission principally considered the succession of States in respect of treaties, Palais des Nations, Geneva: partial view of the Commission in session. 6 May 1974, Twenty-sixth Session of the International Law Commission at which the Commission principally considered the succession of States in respect of treaties, Palais des Nations, Geneva: partial view of the Commission in session. 7 November 1974, Twenty-ninth Session of the General Assembly at which the debate continued in the Sixth Committee on the report of the International Law Commission containing draft articles on succession of States in respect of treaties, United Nations Headquarters, New York: general view of the Committee in session. 22 October 1975, Thirtieth Session of the General Assembly at which the debate continued in the Sixth Committee on the report of the International Law Commission containing draft articles on succession of States in respect of treaties, United Nations Headquarters, New York: at the presiding table are (from left to right) Mr. Abdul Hakim Tabibi (Afghanistan), Chairman of the International Law Commission; Mr. Frank X. Njenga (Kenya), Committee Chairman; Mr. Yuri M. Rybakov (USSR), Committee Secretary; and Mr. Eike Bracklo (Federal Republic of Germany), Rapporteur.
6 May 1974
Twenty-sixth Session of the International Law Commission at which the Commission principally considered the succession of States in respect of treaties, Palais des Nations, Geneva
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6 May 1974
Twenty-sixth Session of the International Law Commission at which the Commission principally considered the succession of States in respect of treaties, Palais des Nations, Geneva
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7 November 1974
Twenty-ninth Session of the General Assembly at which the debate continued in the Sixth Committee on the report of the International Law Commission containing draft articles on succession of States in respect of treaties,
United Nations Headquarters,
New York
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22 October 1975
Thirtieth Session of the General Assembly at which the debate continued in the Sixth Committee on the report of the International Law Commission containing draft articles on succession of States in respect of treaties,
United Nations Headquarters,
New York
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