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Last update: September 24, 2018

Summaries of the Work of the International Law Commission

Subsequent agreements and subsequent practice in relation to interpretation of treaties*

*At its sixty-fourth session, in 2012, the Commission decided to change, in 2013, the format of the work on this topic and its title from "Treaties over time" to "Subsequent agreements and subsequent practice in relation to interpretation of treaties".

See also: Analytical Guide | Texts and Instruments

At its sixtieth session, in 2008, the International Law Commission decided to include the topic "Treaties over time" in its programme of work, on the basis of the recommendation of a Working Group on the long-term programme of work, and to establish a Study Group therefor at its following session in 2009.1

The General Assembly, in resolution 63/123 of 11 December 2008, took note of the decision.

At its sixty-first session, in 2009, the Commission established a Study Group on Treaties over Time, chaired by Mr. Georg Nolte. The Commission subsequently took note of the oral report of the Chair of the Study Group.2

As a basis for the discussion, the Study Group had before it the following documents:

The Study Group agreed on the following:3

At its sixty-second session in 2010, the Study Group on Treaties over time was reconstituted under the Chairship of Mr. Georg Nolte. The Study Group began its work on the aspects of the topic relating to subsequent agreements and practice, on the basis of an introductory report prepared by its Chair on the relevant jurisprudence of the International Court of Justice and arbitral tribunals of ad hoc jurisdiction.4 It recommended that a request for information be included in Chapter III of the Commission's report and be also brought to the attention of States by the Secretariat.5 The Commission took note of the oral report of the Chair of the Study Group on Treaties over time and approved the recommendation concerning the request for information from States.6

At the sixty-third session in 2011, the Commission reconstituted the Study Group on Treaties over time, which continued its work on the aspects of the topic relating to subsequent agreements and practice.7 The Study Group first completed its consideration of the introductory report by its Chair on the relevant jurisprudence of the International Court of Justice and of arbitral tribunals of ad hoc jurisdiction, by examining the section of the report which addressed the question of possible modifications of a treaty by subsequent agreements and practice, and the relation of subsequent agreements and practice to formal amendment procedures, as well as a working paper on evolutionary interpretation. The Study Group then began its consideration of the second report by its Chair on the jurisprudence under special regimes relating to subsequent agreements and practice, by focusing on certain conclusions contained therein. In the light of the discussions, the Chair of the Study Group reformulated the text of nine preliminary conclusions on such issues as reliance by adjudicatory bodies on the general rule of treaty interpretation, different approaches to treaty interpretation, and various aspects concerning subsequent agreements and practice as a means of treaty interpretation.8

At its sixty-fourth session, in 2012, the Commission decided to change, with effect at the next session, the format of the work on this topic and its title as suggested by the Study Group. The Commission also decided to appoint Mr. Georg Nolte as Special Rapporteur for the topic “Subsequent agreements and subsequent practice in relation to interpretation of treaties”.

At the sixty-fifth session in 2013, the Commission had before it the first report of the Special Rapporteur,9 which, inter alia, contained four draft conclusions relating to the general rule and means of treaty interpretation; subsequent agreements and subsequent practice as means of interpretation; the definition of subsequent agreement and subsequent practice as means of treaty interpretation; and attribution of a treaty related practice to a State. Following the debate in plenary, the Commission decided to refer the four draft conclusions to the Drafting Committee. Upon consideration of the report of the Drafting Committee, Commission provisionally adopted draft conclusions 1 to 5.

At the sixty-sixth session in 2014, the Commission had before it the second report of the Special Rapporteur,10 in which the Special Rapporteur considered the following aspects of the topic: the identification of subsequent agreements and subsequent practice; possible effects of subsequent agreements and subsequent practice in the interpretation of treaties; the form and value of subsequent practice under article 31, paragraph 3 (b); the conditions for an “agreement” of the parties regarding the interpretation of a treaty under article 31, paragraph 3; decisions adopted within the framework of Conferences of States Parties; and the possible scope for interpretation by subsequent agreements and subsequent practice. The report also included some information on the future programme of work. The Special Rapporteur proposed draft conclusions 6 to 11, which were subsequently referred to the Drafting Committee. On the basis of the report of the Drafting Committee, the Commission provisionally adopted five draft conclusions, with commentaries.

At the sixty-seventh session in 2015, the Commission had before it the third report of the Special Rapporteur,11 which contained, inter alia, one draft conclusion relating to constituent instruments of international organizations. The Commission subsequently provisionally adopted draft conclusion 11, on the basis of the report of the Drafting Committee report, together with a commentary thereto.

At its sixty-eighth session, in 2016, the Commission had before it the fourth report of the Special Rapporteur,12 addressing the legal significance, for the purpose of interpretation and as forms of practice under a treaty, of pronouncements of expert bodies and of decisions of domestic courts. The report proposed draft conclusions 12 and 13 on those issues. It also discussed the structure and scope of the draft conclusions, proposed the inclusion of a new draft conclusion 1a, and suggested a revision to draft conclusion 4 (3).13 The Commission referred draft conclusions 1a and 12, as presented by the Special Rapporteur, to the Drafting Committee.14 Following presentation and consideration of the report of the Drafting Committee, the Commission adopted, on first reading, a set of 13 draft conclusions, together with commentaries thereto. In accordance with articles 16 to 21 of its Statute, the Commission transmitted the draft conclusions, through the Secretary-General, to Governments for comments and observations, with the request that such comments and observations be submitted to the Secretary-General by 1 January 2018.15

At its seventieth session, the Commission had before it the fifth report of the Special Rapporteur,16 as well as comments and observations received from Governments.17 The Commission commenced the second reading of the draft conclusions on subsequent agreements and subsequent practice in relation to the interpretation of treaties.18 The Commission subsequently adopted, on second reading, a set of 13 draft conclusions, together with commentaries thereto, on subsequent agreements and subsequent practice in relation to the interpretation of treaties.19 In accordance with article 23 of its statute, the Commission recommended that the General Assembly (a) take note in a resolution of the draft conclusions on subsequent agreements and subsequent practice in relation to the interpretation of treaties, annex the draft conclusions to the resolution, and ensure their widest dissemination; and (b) commend the draft conclusions, together with the commentaries thereto, to the attention of States and all who may be called upon to interpret treaties.20

The work of the Commission on the topic as described above has been proceeding in accordance with the resolutions adopted by the General Assembly under the item relating to the report of the International Law Commission.21

1 See Official Records of the General Assembly, Sixty-third Session, Supplement No. 10 (A/63/10), para. 353. For the syllabus on the topic, see ibid., annex A.

2 See Official Records of the General Assembly, Sixty-fourth Session, Supplement No. 10 (A/64/10), paras. 218–219.

3 Ibid., para. 226.

4 See Official Records of the General Assembly, Sixty-fifth Session, Supplement No. 10 (A/65/10), paras. 348–352.

5 Ibid., para. 354.

6 Ibid., para. 346.

7 See Official Records of the General Assembly, Sixty-sixth session, Supplement No. 10 (A/66/10), paras. 334–343.

8 Ibid., para. 344.

9 See document A/CN.4/660.

10 See document A/CN.4/671.

11 See document A/CN.4/683.

12 See document A/CN.4/694.

13 Official Records of the General Assembly, Seventy-first Session, Supplement No. 10 (A/71/10), para. 70.

14 Ibid., para. 71.

15 Ibid., paras. 72–73 and 75–76.

16 See document A/CN.4/715.

17 See documents A/CN.4/712 and Add.1.

18 Official Records of the General Assembly, Seventy-third Session, Supplement No. 10 (A/73/10), para. 45.

19 Ibid., paras. 46, 47, 51 and 52.

20 Ibid., para. 49.

21 General Assembly resolution 63/123 of 11 December 2008; 64/114 of 16 December 2009; 65/26 of 6 December 2010; 66/98 of 9 December 2011; 69/118 of 10 December 2014; 70/236 of 23 December 2015; and 71/140 of 13 December 2016.