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Abstract

The legal standing of joint statements in international law remains contested, particularly with respect to their qualification as treaties under the Vienna Convention on the Law of Treaties. This issue has become increasingly relevant following the 2024 Joint Statement between Indonesia and China on Advancing the Comprehensive Strategic Partnership and the China-Indonesia Community with a Shared Future. Despite its political framing, item nine, which contains a provision on joint development in areas described as overlapping claims in the South China Sea, raises critical legal concerns that the implications may constitute a legally binding treaty. This article employs a doctrinal legal method. It analyzes the Joint Statement through treaty law principles derived from the VCLT, relevant International Court of Justice jurisprudence, travaux préparatoires, and comparative State practice in Southeast Asia. This study examines whether the Joint Statement meets all conditions under Article 2 VCLT and can be considered as a legally binding treaty between Indonesia and China. Furthermore, it also discusses the potential for treaty conflict between item nine of the Joint Statement and UNCLOS and analyzes the mechanism for resolving it through Article 311 of UNCLOS. This study also highlights the need for greater legal precision in Indonesia's diplomatic instruments Without such precision, politically framed agreements may generate unintended legal consequences, particularly in relation to maritime sovereignty and jurisdiction.

References

1. Aust, Anthony. Modern Treaty Law and Practice, 3rd ed. (UK: Cambridge University Press, 2013).
2. Rothwell, Donald R. and Tim Stephens, The International Law of the Sea, (UK: Hart Publishing, 2016).
3. Hollis, Duncan B. The Oxford Guide to Treaties, (Oxford: Oxford Academic, 2020).
4. Gardiner, R, Treaty Interpretation, (United Kingdom: Oxford University Press, 2015).
5. Harold Nicolson, Diplomacy, (UK: Oxford University Press, 1952).
6. Crawford, James. Brownlie's Principles of Public International Law 9th ed. (UK: Oxford University Press 2019).
7. Klabbers, Jan. The Concept of Treaty in International Law 22. (The Netherlands: Brill | Nijhoff, 1996)
8. Pauwelyn, Joost. Conflict of Norms in Public International Law: How WTO Law Relates to Other Rules of International Law (UK: Cambridge University Press, 2003).
9. Lord McNair, The Law of Treaties, (UK: Oxford University Press, 1961).
10. Fitzmaurice, Malgosia, Panos Merkouris. Treaties in Motion: The Evolution of Treaties from Formation to Termination, Cambridge University Press (2020).
11. Klein, Natalie, Maritime Security and the Law of the Sea, (Oxford: Oxford University Press, 2011).
12. Dorr, Oliver. ``Article 2 Use of Terms'', in Vienna Convention on the Law of Treaties: A Commentary, (Berlin: Springer Berlin Heidelberg).
13. Gardiner, Richard K. Treaty Interpretation (UK: Oxford University Press, 2015).
14. Kolb, Robert. The Law of Treaties: An Introduction, (United Kingdom: Edward Elgar Publishing Limited, 2016).
15. Rothwell, D.R., and T. Stephens, The International Law of the Sea, (UK: Hart Publishing, 2016).
16. Sadat, Seyed Ali. Methods of Resolving Conflicts Between Treaties, (Netherlands: Brill Academic Publishers, 2003).
17. Jayakumar, S. et al., The South China Sea Disputes and Law of the Sea, (US: Edward Elgar Publishing, 2014).
18. Villiger, M. E., Commentary on the 1969 Vienna Convention on the Law of Treaties, (The Netherlands: Brill Nijhoff, 2008).
19. Shicun, Wu and Nong Hong, Recent Developments in the South China Sea Dispute: The Prospects of a Joint Development Regime, (New York: Routledge, 2014).
20. Tanaka, Yoshifumi. The International Law of the Sea, (Cambridge: Cambridge University Press, 2019). Other Documents

21. ``Agreement between Japan and the Republic of Korea Concerning Joint Development of the Southern Part of the Continental Shelf Adjacent to the Two Countries'', 30 January 1974, 1225 UNTS.
22. ``Joint Statement Between the People's Republic of China and the Republic of Indonesia on Advancing the Comprehensive Strategic Partnership and the China-Indonesia Community with a Shared Future'' Beijing, November 9, 2024.
23. ``Keterangan Pers Tentang Kerja Sama Maritim RI-Tiongkok Dalam Pernyataan Bersama RI-TiongkokKeterangan Pers Tentang Kerja Sama Maritim RI-Tiongkok Dalam Pernyataan Bersama RI-Tiongkok``, Kementerian Luar Negeri Republik Indonesia, https://kemlu.go.id/berita/keterangan-pers-tentang–kerja-sama-maritim-ri-tiongkok-dalam–pernyataan-bersama-ri-tiongkok?type=publication.
24. ``Komitmen Investasi Senilai USD10,07 Miliar Dihasilkan Dalam Kunjungan Kenegaraan Prabowo ke RRT, Rosan Optimis Investasi Tiongkok Terus Meningkat,'' Kementerian Investasi dan Hilirisasi/BKPM, last modified November 12, 2025, https://www.bkpm.go.id/id/info/siaran-pers/komitmen-investasi-senilai-usd10-07-miliar-dihasilkan-dalam-kunjungan-kenegaraan-prabowo-ke-rrt-rosan-optimis-investasi-tiongkok-terus-meningkat.
25. ``Memorandum of Understanding between Malaysia and the Kingdom of Thailand on the Establishment of a Joint Authority for the Exploitation of the Resources in the Sea-Bed in a Defined Area of the Continental Shelf of the Two Countries in the Gulf of Thailand'', 21 February 1979, entered into force 24 October 1979.
26. ``Philippines' Teodoro issues `wake-up call' for Asean unity to `resist coercion''', South China Morning Post, last modified February 27, 2025, https://www.scmp.com/week-asia/politics/article/3300358/ philippines-teodoro-issues-wake-call-asean-unity-resist-coercion?module=perpetual_scroll1_AI&pgtype=article.
27. ``United Nations Convention on the Law of the Sea,'' opened for signature December 10, 1982, United Nations Treaty Series 1833.
28. ``Vienna Convention on the Law of Treaties'', opened for signature May 23, 1969, United Nations Treaty Series 1155.
29. ``Vietnam, China issue joint statement'' VN Express, last modified April 15, 2025, https://e.vnexpress.net/news/news /politics/ vietnam-china-issue-joint-statement- 4874469.html.
30. Aegean Sea Shelf Case (Greece vs Turkey), Judgment, ICJ Rep 1978.
31. Andi, I Made ``Criticizing the Maritime Cooperation between Indonesia and China'', last modified November 16, 2024, https://madeandi.staff.ugm.ac.id/criticizing-the-maritime-cooperation-between-indonesia-and-china/.
32. Zimmerman, Andreas. ``Possible indirect legal effects of non-legally binding instruments''. Cadhi Expert Workshop, Universität Postsdam, March 2021.
33. Case Concerning the Territorial Dispute (Libyan Arab Jamahiriya/Chad), Judgment, ICJ Rep 1994.
34. Chinkin, CM. ``The Challenge of Soft Law: Development and Change in International Law''. International and Comparative Law Quarterly 38 No.4 (1989).
35. Weatherbee, D. E. ``Indonesia, ASEAN, and the Quest for an Effective South China Sea Mechanism,'' Contemporary Southeast Asia 42 No. 3 (2020).
36. Darmawan, Aristyo Rozka. ``Has Indonesia fallen into China's nine-dash line trap?'', the interpreter, 12 November 2024, https://www.lowyinstitute.org/the-interpreter/has-indonesia-fallen-china-s-nine-dash-line-trap.
37. Glodi\\'c, Duško. ``Use of Legally Non-Binding Instruments in Contemporary Practice of International Relations''. GODIŠNJAK FAKULTETA PRAVNIH NAUKA. (2021).
38. International Law Commission, ``Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of InternationalLaw'', (13 April 2006) UN Doc. A/CN.4/L.682, 2006.
39. International Law Commission, ``ILC Commentary to the Draft Articles on the Law of Treaties'', Yearbook of the International Law Commission, Vol. II, (1966) 189.
40. Harrison, James. ``Evolution of the Law of the Sea: Developments in Law-Making in the Wake of the 1982 Law of the Sea Convention'', Edinburgh School of Law Working Papers 15, (2007).
41. Harrison, James. ``Evolution of the Law of the Sea: Developments in Law-Making in the Wake of the 1982 Law of the Sea Convention'', Edinburgh School of Law Working Papers 15, (2007).
42. Klein, N. ``The South China Sea Arbitration and Maritime Law''. Australian Yearbook of International Law 34, (2017).
43. Land and Maritime Boundary between Cameroon and Nigeria, (Cameroon v. Nigeria Judgment), [2002], ICJ Reports 263–264.
44. Lekkas, et al. ``The Interpretative Practice of the International Court of Justice'', Max Planck Yearbook of United Nations Law Online 26, No.1 (2023).
45. Maritime Delimitation and Territorial Questions (Qatar v Bahrain Jurisdiction and Admissibility) [1994]ICJ Rep 24.
46. Nguyen, H. T., and T. M. Tran, ``China's Strategic Use of Joint Statements in South China Sea Diplomacy,'' Ocean Development & International Law 52 No.2, (2021).
47. Official Records of the Third United Nations Conference on the Law of the Sea, Vol XVII (United Nations Publication 1984).
48. Pulp Mills on the River Uruguay (Argentina v Uruguay Judgment) [2010]ICJ Rep 132 –133.
49. Michaels, R. and J Pauwelyn, ``Conflict of Norms or Conflict of Laws?: Different Techniques in the Fragmentation of Public International Law'', Duke J Comp & Int'l L 349, (2012).
50. Beckman, R. ``The UN Convention on the Law of the Sea and the Maritime Disputes in the South China Sea,'' American Journal of International Law 107 No. 1 (2018).
51. Wardhana, Rifqi Setia. ``South China Sea Conflict and Security Cooperation in ASEAN Waters.'' Indonesian Journal of Peace and Security Studies 3 no. 1 (2020).
52. The South China Sea Arbitration (Philippines v. China Award) [2016].
53. United Nations International Law Commission, ``Report on the Law of Treaties,'' Yearbook of the International Law Commission 2 (1950).
54. Yearbook of the International Law Commission (1962/1), Volume I, Summary records of the fourteenth session A/C.N.4/Ser.A/1962, at 52. https://legal.un.org/ilc/publications/yearbooks/english/ilc1962_v1.pdf.
55. Sulistyani, Yuli Ari et al., ``Indonesia's Responses toward the South China Sea Dispute During Joko Widodo's Administration.'' Jurnal Politica 12 No. 1 (2021).

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