At its first session, in 1949, the 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 (E, F, S, R, C, A), recommending that the Commission include on its priority list the topic of succession of States and Governments. In principle, all members of the Commission were in favour of including the topic on its priority list, but there were divergent views concerning the scope of the topic and the best approach to its study. 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. [1]

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

At its fifteenth session, in 1963, the Commission considered and unanimously approved the report of the Subcommittee. [2]  In the opinion of the Commission, the priority given to the study of the question of State succession was fully justified, and it was agreed that the question of the succession of Governments would, for the time being, be considered only to the extent necessary to supplement the study on State succession. Several members of the Commission stressed the importance which State succession had for new States and for the international community in view of the phenomenon of decolonization, and agreed with the Subcommittee’s view that special attention should be given in the study to the problems of concern to new States.

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 objectives proposed by the Subcommittee — a survey and evaluation of the current state of the law and practice in the matter of State succession and the preparation of draft articles on the topic in the light of new developments in international law — were approved by all members of the Commission. The Commission appointed Manfred Lachs as Special Rapporteur for the topic.

The General Assembly, in resolution 1902 (XVIII) of 18 November 1963 (E, F, S, R, C, A), recommended that the Commission should “continue its work on the succession of States and Governments, taking into account the views expressed at the eighteenth session of the General Assembly, the report of the Subcommittee on the Succession of States and Governments and the comments which may be submitted by Governments, with appropriate reference to the views of States which have achieved independence since the Second World War”.

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, and decided to leave aside for the time being the third aspect, succession in respect of membership of international organizations, without assigning it to a Special Rapporteur. It was considered that the third aspect related both to succession in respect of treaties and to relations between States and international organizations. In accordance with the decision taken in 1963, it was agreed to give priority to the study of State succession, considering the study of succession of Governments only to the extent necessary to supplement the study of State succession.

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