¹ According to UNEP, marine litter is defined as ‘any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment’: UNEP, ‘Marine Litter’, available at: https://www.unep.org/explore-topics/oceans-seas/what-we-do/working-regional-seas/marine-litter. For the purpose of this article, marine plastic litter refers to marine litter which consists of items including plastics. For a study that estimates that 75% of all marine litter is plastic, see Napper, I.E. & Thompson, R.C., ‘Plastic Debris in the Marine Environment: History and Future Challenge’ (2020) 4(6) Global Challenges, pp. 1–9, at 1CrossRefGoogle Scholar.

² Plastics can be categorized depending on particular size as: macroplastics (with particles larger than 2.5 cm), mesoplastics (with particles between 5 mm and 2.5 cm), microplastics (with particles between 1 µm and 5 mm), and nanoplastics (with particles between 1 and 100 nm): see Barcelo, D. & Pico, Y., ‘Case Studies of Macro-and Microplastics Pollution in Coastal Waters and Rivers: Is There a Solution with New Removal Technologies and Policy Actions?’ (2020) 2 Case Studies in Chemical and Environmental Engineering, pp. 1–5, at 1CrossRefGoogle Scholar. There are several variations on the size of these particles in addition to those shown here; for further discussion see, e.g., UNEP, From Pollution to Solution: A Global Assessment of Marine Litter and Plastic Pollution (UNEP, 2021), pp. 11–2, available at: https://www.unep.org/resources/pollution-solution-global-assessment-marine-litter-and-plastic-pollution.

³ UNEP, From Pollution to Solution: A Global Assessment of Marine Litter and Plastic Pollution – Synthesis (UNEP, 2021), p. 3, available at: https://wedocs.unep.org/bitstream/handle/20.500.11822/36965/POLSOLSum.pdf.

⁴ UN Environment Assembly Res. 4/6, ‘Marine Plastic Litter and Microplastics’, 15 Mar. 2019, UN Doc. UNEP/EA.4/Res.6, Preamble, available at: https://wedocs.unep.org/bitstream/handle/20.500.11822/28471/English.pdf?sequence=3&isAllowed=y.

⁵ Oral, N., ‘From the Plastics Revolution to the Marine Plastics Crisis: A Patchwork of International Law’, in Barnes, R. & Long, R. (eds), Frontiers in International Environmental Law: Oceans and Climate Challenge, Essays in Honour of David Freestone (Brill/Nijhoff, 2021), pp. 281–315, at 286Google Scholar; Eriksen, M. et al., ‘Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighting over 250,000 Tons Afloat at Sea’ (2014) 9(12) PLoS ONE, article e111913, pp. 1–15, at 10CrossRefGoogle Scholar.

⁶ Ibid., p. 11.

⁷ UNEP refers to the following negative impacts on the marine environment: mortality or sub-lethal effects when plastic is ingested by animals such as turtles, small-toothed whales, and seabirds; entanglement of animals such as dolphins and large whales in nylon fishing gear (like nets) and other plastic debris; damage to critical ecosystems such as coral reefs and smothering of sediments; chemical contamination of marine organisms through ingestion of small plastic particles; and potential changes in biodiversity as a result of the transport of invasive species on plastic fragments: UNEP Year Book 2014: Emerging Issues in Our Global Environment (UNEP, 2014), p. 49, available at: https://wedocs.unep.org/handle/20.500.11822/9130. See also Beamont, N.J. et al., ‘Global Ecological, Social and Economic Impacts of Marine Plastic’ (2019) 142 Marine Pollution Bulletin, pp. 189–95CrossRefGoogle Scholar.

⁸ Montego Bay (Jamaica), 10 Dec. 1982, in force 16 Nov. 1994, available at: http://www.un.org/depts/los/convention_agreements/convention_overview_convention.htm. Art. 1(1)–(4) UNCLOS defines ‘pollution of the marine environment’ as ‘the introduction by man, directly or indirectly, of substances or energy into the marine environment, including estuaries, which results or is likely to result in such deleterious effects as harm to living resources and marine life, hazards to human health, hindrance to marine activities, including fishing and other legitimate uses of the sea, impairment of quality for use of sea water and reduction of amenities’.

⁹ Boyle, A. & Redgwell, C., Birnie, Boyle and Redgwell's International Law and the Environment, 4^th edn (Oxford University Press, 2021), p. 511CrossRefGoogle Scholar; Sands, P. et al., Principles of International Environmental Law, 3^rd edn, (Cambridge University Press, 2012), p. 350CrossRefGoogle Scholar; Czybulka, D., ‘Article 192’, in Proelss, A. (ed.), The United Nations Convention on the Law of the Sea: A Commentary (Hart, 2017), pp. 1277–87Google Scholar, at 1284–5.

¹⁰ See Section 2.1 of this article.

¹¹ Art. 2 of the International Law Commission (ILC) Articles on State Responsibility, reproduced in Crawford, J., The International Law Commission's Articles on State Responsibility: Introduction, Text and Commentaries (Cambridge University Press, 2002), p. 61Google Scholar.

¹² Ibid., pp. 84, 203.

¹³ Ibid., p. 91

¹⁴ Ibid., p. 92.

¹⁵ Johnstone, R.L., Offshore Oil and Gas Development in the Arctic under International Law: Risk and Responsibility (Nijhoff, 2015), p. 198CrossRefGoogle Scholar.

¹⁶ Koivurova, T., ‘Due Diligence’, in Wolfrum, R. (ed.), Max Planck Encyclopedias of International Law (online, Oxford University Press, 2010), para. 19Google Scholar.

¹⁷ L. Finska, ‘Confronting the Global Plastics Problem Threatening the Marine Environment: A Framework and Elements of an International Legal Response’ (Doctoral dissertation, Faculty of Law, UiT The Arctic University of Norway, 2021), pp. 158–9, available at: https://munin.uit.no/handle/10037/23741.

¹⁸ According to Nolkaemper, the concept of shared responsibility refers to ‘situations where a multiplicity of actors contributes to a single harmful outcome, and legal responsibility for this harmful outcome is distributed among more than one of the contributing actors’: Nollkaemper, A., ‘Introduction’, in Nollkaemper, A. & Plakokefalos, I. (eds), Principles of Shared Responsibility in International Law: An Appraisal of the State of the Art (Cambridge University Press, 2014), pp. 1–24CrossRefGoogle Scholar, at 6–7. According to Nedeski, shared responsibility is an inevitable consequence of a breach of an indivisible shared obligation: Nedeski, N., Shared Obligations in International Law (Cambridge University Press, 2022), p. 222CrossRefGoogle Scholar.

¹⁹ Permanent Court of International Justice (PCIJ), Factory at Chorzów, Merits, PCIJ Series A No. 17, 1928, p. 47. For the remedial function of the law of state responsibility, see D. Shelton, ‘Righting Wrongs: Reparations in the Articles on State Responsibility’ (2002) 96(4) American Journal of International Law, pp. 833–56, at 844.

²⁰ A comprehensive examination of shared responsibility in various fields of international law was made by A. Nollkaemper & I. Plakokefalos (eds), The Practice of Shared Responsibility in International Law (Cambridge University Press, 2017). While shared state responsibility for marine plastic pollution was not discussed in the book, shared state responsibility for land-based marine pollution was examined in Y. Tanaka, ‘Land-Based Marine Pollution’, in Nollkaemper & Plakokefalos, ibid., pp. 294–315.

²¹ E.g., Maljean-Dubois and Mayer considered liability for marine plastic pollution, but no discussion was made with regard to shared state responsibility: Maljean-Dubois, S. & Mayer, B., ‘Liability and Compensation for Marine Plastic Pollution: Conceptual Issues and Possible Ways Forward’ (2020) 114 American Journal of International Law Unbound, pp. 206–11Google Scholar. While Finska examined some relevant issues of state responsibility for marine plastic pollution, no consideration was given to shared state responsibility: Finska, n. 17 above, pp. 155–83.

²² N. 11 above. Nollkaemper, n. 18 above, p. 3.

²³ D. McRae, ‘Introduction to the Symposium on Global Plastic Pollution’ (2020) 114 American Journal of International Law Unbound, pp. 192–4, at 192; Schäli, J., ‘Marine Plastic Pollution as a Common Concern of Mankind’, in Cottier, T. & Ahmad, Z. (eds), The Prospects of Common Concern of Humankind in International Law (Cambridge University Press, 2021), pp. 153–98CrossRefGoogle Scholar, at 160; Oral, n. 5 above, p. 287. Land-based sources are responsible for approximately 80% of marine pollution: UN General Assembly, ‘Oceans and the Law of the Sea: Report of the Secretary-General’, 18 Aug. 2004, UN Doc. A/59/62/Add.1, p. 29, para. 97, available at: https://documents-dds-ny.un.org/doc/UNDOC/GEN/N04/464/58/PDF/N0446458.pdf?OpenElement.

²⁴ It is not suggested that ocean-based marine plastic pollution is less important; on this issue, see Oral, n. 5 above, pp. 296–305; Finska, n. 17 above, pp. 75–94.

²⁵ UNCLOS refers to ‘prevent, reduce and control’ in provisions concerning marine environmental protection. However, that phrase is not defined in the Convention and the relationship between prevention, reduction and control remains obscure: R. Churchill, V. Lowe & A. Sander, The Law of the Sea, 4^th edn (Manchester University Press, 2022), pp. 623–4. In the view of the ILC, the obligation to ‘prevent’ relates to new pollution and the obligations to ‘reduce’ and ‘control’ relate to existing pollution: ILC, Draft Articles on the Law of Non-Navigational Uses of International Watercourses (1994) II(2) Yearbook of the International Law Commission, pp. 89–135, Commentary on Draft Article 21, p. 122, para. 4. Yet, there seems to be no clear reason why the obligation to prevent is not applicable to existing pollution. Prevention, reduction and control commonly aim to minimize marine pollution. For the sake of simplicity, this article uses the term ‘prevention’ rather than the somewhat burdensome phrase ‘prevent, reduce and control’, and the concept of ‘prevention’ should be taken to cover ‘reduction’ and/or ‘control’ where appropriate.

²⁶ Permanent Court of Arbitration, Case No. 2013-19, South China Sea Arbitration (Philippines v. China), Case No. 2013-19, Award of 12 July 2016, (2020) XXXIII Reports of International Arbitral Awards (RIAA), p. 153, at 519, para. 941.

²⁷ Ibid., p. 526, para. 956.

²⁸ ITLOS, Southern Bluefin Tuna Cases (New Zealand v. Japan; Australia v. Japan), Case Nos 3 and 4, Provisional Measures, Order of 27 Aug. 1999, ITLOS Reports (1999), p. 280, at 295, para. 70.

²⁹ ITLOS, Responsibilities and Obligations of States Sponsoring Persons and Entities with respect to Activities in the Area, Advisory Opinion, 1 Feb. 2011, ITLOS Reports (2011), p. 10, at 59, para. 180.

³⁰ Johnstone, n. 15 above, p. 223; Rao, P. Chandrasekhara & Gautier, P., The International Tribunal for the Law of the Sea: Law, Practice and Procedure (Edward Elgar, 2018), p. 327Google Scholar; Tanaka, Y., ‘The Legal Consequences of Obligations Erga Omnes in International Law’ (2021) 68(1) Netherlands International Law Review, pp. 1–33, at 5CrossRefGoogle Scholar.

³¹ Harrison, J., Saving the Oceans through Law: The International Legal Framework for the Protection of the Marine Environment (Oxford University Press, 2017), pp. 24–5Google Scholar; Tanaka, n. 30 above, p. 5.

³² The concept of obligations erga omnes partes is distinct from that of obligations erga omnes. According to the Institut de Droit International, an obligation erga omnes partes refers to ‘an obligation under a multilateral treaty that a State party to the treaty owes in any given case to all the other States parties to the same treaty’, while an obligation erga omnes refers to ‘an obligation under general international law that a State owes in any given case to the international community’: Institut de Droit International, ‘Resolution: Obligation Erga Omnes in International Law, Krakow Session 2005’, Art. 1, available at: http://www.idi-iil.org/app/uploads/2017/06/2005_kra_01_en.pdf. Crawford seemed to assimilate ‘communitarian norms’ with obligations erga omnes: Crawford, J., Chance, Order, Change: The Course of International Law (Brill/Nijhoff, 2014), p. 260Google Scholar.

³³ ICJ, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 8 July 1996, ICJ Reports (1996), p. 226, at 241–2, para. 29. This dictum was confirmed by the ICJ in Gabčíkovo-Nagymarous Project (Hungary/Slovakia), Judgment, 25 Sept. 1997, ICJ Reports (1997), p. 7, at 41, para. 53.

³⁴ Boyle & Redgwell, n. 9 above, p. 152; Koivurova, n. 16 above, para. 3.

³⁵ Trail Smelter Arbitration, Award of Arbitral Tribunal, 11 Mar. 1941, (2006) 3 RIAA, pp. 1905–82.

³⁶ Adopted by the UN Conference on Environment and Development, Rio de Janeiro (Brazil), 3–14 June 1992, UN Doc. A/CONF.151/26/Rev.1 (Vol. I), Annex I, available at: https://www.un.org/esa/dsd/agenda21/Agenda%2021.pdf.

³⁷ Boyle & Redgwell, n. 9 above, p. 162.

³⁸ This provision evolved from Principle 21 of the Stockholm Declaration (Declaration of the United Nations Conference on the Human Environment, adopted by the UN Conference on Environment and Development, Stockholm (Sweden), 5–16 June 1972, UN Doc. A/Conf.48/14/Rev. 1); D. Czybulka, ‘Article 194’, in Proelss, n. 9 above, pp. 1295–315, at 1306.

³⁹ Koivurova, n. 16 above, para. 8. An obligation of conduct is regarded as a best-efforts obligation: Nedeski, n. 18 above, p. 108. See also Clawford, J., State Responsibility: The General Part (Cambridge University Press, 2013), pp. 226–32CrossRefGoogle Scholar.

⁴⁰ Koivurova, n. 16 above, para. 30.

⁴¹ S. Besson, La due diligence en droit international (Brill/Nijhoff, 2021), p. 138.

⁴² Responsibilities and Obligations of States Sponsoring Persons, n. 29 above, p. 43, para. 117.

⁴³ ILC, ‘Draft Articles on Prevention of Transboundary Harm from Hazardous Activities with Commentaries’, Report of the ILC on its 53^rd Session, 23 Apr.–1 June and 2 July–10 Aug. 2001, UN Doc. A/56/10, p. 154, para. 11, Commentary to Art. 3, available at: http://legal.un.org/ilc/documentation/english/reports/a_56_10.pdf.

⁴⁴ Koivurova, n. 16 above, para. 19.

⁴⁵ Boyle and Redgwell, n. 9 above, p. 162.

⁴⁶ R. Wolfrum, ‘Purposes and Principles of International Environmental Law’ (1990) 33 German Yearbook of International Law, pp. 308–30, at 317.

⁴⁷ The ILC recognized that the term ‘significant’ is not without ambiguity and that a determination has to be made in each specific case: ILC, n. 43 above, p. 152, para. 4. See also O. Schachter, International Law in Theory and Practice (Brill/Nijhoff, 1991), p. 366.

⁴⁸ Arts 208(3), 210(6) and 211(2) UNCLOS.

⁴⁹ A.E. Boyle, ‘Marine Pollution under the Law of the Sea Convention’ (1985) 79 American Journal of International Law, pp. 347–72, at 354; Tanaka, n. 20 above, p. 300.

⁵⁰ Reproduced in H. Hohmann (ed.), Basic Documents of International Environmental Law, vol. I (Graham & Trotman, 1992), pp. 130–47.

⁵¹ Available at: https://sdgs.un.org/publications/agenda21.

⁵² Available at: http://wedocs.unep.org/handle/20.500.11822/13421.

⁵³ UN Doc. UNEP(OCA)/LBA/IG.2/7 5, Dec. 1995, available at: https://wedocs.unep.org/bitstream/handle/20.500.11822/13422/GPAFullTextEn.pdf?sequence=1&isAllowed=y.

⁵⁴ (2002) 48 Law of the Sea Bulletin, pp. 58–61.

⁵⁵ UN Doc. UNEP/GPA/IGR.3/CRP.1/Rev.1, 26 Jan. 2012, available at: https://wedocs.unep.org/bitstream/handle/20.500.11822/12347/ManillaDeclarationREV.pdf?sequence=1&isAllowed=y.

⁵⁶ Boyle & Redgwell, n. 9 above, pp. 467, 477.

⁵⁷ Tanaka, n. 20 above, p. 299.

⁵⁸ ITLOS, The MOX Plant Case (Ireland v. United Kingdom), Provisional Measures, Order of 3 Dec. 2001, ITLOS Reports (2001), p. 110, para. 82.

⁵⁹ R. Wolfrum, Solidarity and Community Interests: Driving Forces for the Interpretation and Development of International Law (Brill/Nijhoff, 2021), pp. 243 et seq.

⁶⁰ Gattini also considered that ‘[t]his category of obligations [i.e. obligations erga omnes] seems especially suitable for developing a general concept of shared responsibility’: A. Gattini, ‘Breach of International Obligations’, in Nollkaemper & Plakokefalos, n. 18 above, pp. 25–59, at 32.

⁶¹ According to Nedeski, the majority of obligations in the context of cooperation and the pursuit of common goals are obligations of conduct: Nedeski, n. 18 above, p. 129.

⁶² Nollkaemper, n. 18 above, pp. 9–10.

⁶³ In space law, e.g., a lex specialis on shared state responsibility can be found in Art. IV(1) of the Convention on the International Liability for Damage caused by Space Objects, Washington, DC (US), Moscow (USSR), and London (United Kingdom), 29 Mar. 1972, in force 1 Sept. 1972, available at: https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/introliability-convention.html#:~:text=Elaborating%20on%20Article%207%20of,to%20its%20faults%20in%20space.

⁶⁴ Responsibilities and Obligations of States Sponsoring Persons and Entities, n. 29 above, p. 30, para. 66.

⁶⁵ T. Stephens, ‘Article 235’, in Proelss, n. 9 above, pp. 1585–90, at 1588.

⁶⁶ Helsinki (Finland), 9 Apr. 1992, in force 17 Jan. 2000, available at: https://helcom.fi/about-us/convention.

⁶⁷ Cartagena (Colombia), 24 Mar. 1983, in force 11 Oct. 1986, Art.14, available at: https://wedocs.unep.org/bitstream/handle/20.500.11822/27875/SPAWSTAC5_2012-en.pdf?sequence=1&isAllowed=y.

⁶⁸ Finska, n. 17 above, p. 156. This is not a particular problem that arises in the prevention of land-based marine plastic pollution only. Nollkaemper and Plakokefalos indicated that ‘most regimes that protect public interests have not developed special rules regarding responsibility’: A. Nollkaemper and I. Plakokefalos, ‘Conclusions’, in Nollkaemper and Plakokefalos, n. 20 above, pp. 1097–115, at 1114.

⁶⁹ By way of example, the ILC Commentary refers to breach of Art. 194 UNCLOS: Crawford, n. 11 above, p. 259.

⁷⁰ By way of example, the ILC Commentary refers to the situation where ‘several States might contribute to polluting a river by the separate discharge of pollutants’: ibid., p. 274.

⁷¹ Ibid., p. 272.

⁷² Ibid., pp. 274–5.

⁷³ ICJ, Certain Phosphate Lands in Nauru (Nauru v. Australia), Preliminary Objections, Judgment, 26 June 1992, ICJ Reports (1992), pp. 258–9, para. 48.

⁷⁴ See also Principles 2, 3 and 4 of of the the Guiding Principles on Shared Responsibility in International Law (Guiding Principles): Nollkaemper, A. et al., ‘Guiding Principles on Shared Responsibility in International Law’ (2020) 31(1) European Journal of International Law, pp. 15–72CrossRefGoogle Scholar, at 16–7. The Guiding Principles have been elaborated by a group of international lawyers, and ‘provide guidance to judges, practitioners and researchers when confronted with legal questions of shared responsibility of states and international organizations’: ibid., pp. 20–1.

⁷⁵ ILC, Articles on State Responsibility, Art. 14(2), in Crawford, n. 11 above, p. 63.

⁷⁶ Crawford, ibid., p. 141, para. 1.

⁷⁷ Finska, n. 17 above, pp. 167–8.

⁷⁸ See also Guiding Principles, Principle 9: Nollkaemper et al., n. 74 above, p. 51

⁷⁹ See also Nedeski, n. 18 above, p. 180.

⁸⁰ Principle 14(1): Nollkaemper et al., above n. 74, p. 20.

⁸¹ The term ‘not directly injured States’ was used in Kawasaki, K., ‘The “Injured State” in the International Law of State Responsibility’ (2000) 28 Hitotsubashi Journal of Law and Politics, pp. 17–31Google Scholar, at 22.

⁸² Institut de Droit International, n. 32 above.

⁸³ ICJ, Questions relating to the Obligation to Prosecute or Extradite (Belgium v. Senegal), Judgment, 20 July 2012, ICJ Reports (2012), p. 422.

⁸⁴ New York, NY (US), 10 Dec. 1984, in force 26 June 1987, available at: https://www.ohchr.org/sites/default/files/cat.pdf.

⁸⁵ Questions relating to the Obligation to Prosecute or Extradite, n. 83 above, p. 450, para. 70.

⁸⁶ Ibid., p. 448, paras 64–5.

⁸⁷ Ibid., para. 69.

⁸⁸ ICJ, Application of the Convention on the Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar), Provisional Measures, Order, 23 Jan. 2020, ICJ Reports (2020), p. 3, at 17, para. 41.

⁸⁹ Ibid., para. 42. Convention on the Prevention and Punishment of the Crime of Genocide, Paris (France), 9 Dec. 1948, in force 12 Jan. 1951, available at: https://www.ohchr.org/en/instruments-mechanisms/instruments/convention-prevention-and-punishment-crime-genocide.

⁹⁰ ICJ, Application of the Convention on the Prevention and Punishment of the Crime of Genocide (The Gambia v. Mynmar), Preliminary Objections, Judgment, 22 July 2022, ICJ Reports (2022), p. 1, at 38, para. 115(5); see also para. 112.

⁹¹ ICJ, Whaling in the Antarctic (Australia v. Japan: New Zealand intervening), Judgment, 31 Mar. 2014, ICJ Reports (2014), p. 226.

⁹² San Francisco, CA (US), 26 June 1945, in force 24 Oct. 1945, available at: http://www.icj-cij.org/en/statute. Australia and Japan accepted the jurisdiction of the ICJ in 2002 and 2007, respectively.

⁹³ H. Sakai, ‘After the Whaling in the Antarctic Judgment: Its Lessons and Prospects from a Japanese Perspective’, in M. Fitzmaurice & D. Tamada (eds), Whaling in the Antarctic: Significance and Implications of the ICJ Judgment (Nijhoff/Brill, 2016), pp. 308–45, at 314.

⁹⁴ J. Crawford, ‘Responsibility for Breaches of Communitarian Norms: An Appraisal of Article 48 of the ILC Articles on Responsibility of States for Internationally Wrongful Acts’, in U. Fastenrath et al. (eds), From Bilateralism to Community Interest: Essays in Honour of Judge Bruno Simma (Oxford University Press, 2011), pp. 224–40, at 236. See also M. Fitzmaurice, Whaling and International Law (Cambridge University Press, 2015), p. 110; International Convention for the Regulation of Whaling, Washington, DC (US), 2 Dec. 1946, in force 10 Nov. 1948, available at: https://archive.iwc.int/pages/view.php?ref=3607&k=.

⁹⁵ Whaling in the Antarctic, n. 91 above, p. 246, para. 41.

⁹⁶ South China Sea Arbitration, n. 26 above.

⁹⁷ Tanaka, Y., The South China Sea Arbitration: Toward an International Legal Order in the Oceans (Hart, 2019), p. 193CrossRefGoogle Scholar.

⁹⁸ South China Sea Arbitration, n. 26 above, p. 515, para. 927.

⁹⁹ ICJ, Obligations concerning Negotiations relating to Cessation of the Nuclear Arms Race and to Nuclear Disarmament (Marshall Islands v. United Kingdom), Preliminary Objections, Judgment, 5 Oct. 2016, ICJ Reports (2016), p. 833, Dissenting Opinion of Judge Crawford, p. 1102, para. 22. See also C.J. Tams, Enforcing Obligations Erga Omnes in International Law (Cambridge University Press, 2005), pp. 210–1; C.J. Tams & A. Asteriti, ‘Erga Omnes, Jus Cogens and their Impact on the Law of Responsibility’, in M. Evans & P. Koutrakos (eds), The International Responsibility of the European Union: European and International Perspective (Hart, 2013), pp. 163–88, at 170; Tanaka, n. 30 above, p. 23.

¹⁰⁰ Nollkaemper et al., n. 74 above, p. 20.

¹⁰¹ Kirk, E.A. & Popattanachai, N., ‘Marine Plastics: Fragmentation, Effectiveness and Legitimacy in International Lawmaking’ (2018) 27(3) Review of European, Comparative and International Environmental Law, pp. 222–33CrossRefGoogle Scholar, at 223–4. See also Nedeski, n. 18 above, p. 190; Finska, n. 17 above, pp. 164–5.

¹⁰² M. Bergmann, L. Gutow & M. Klages, ‘Preface’, in M. Bergmann, L. Gutow & M. Klages (eds), Marine Anthropogenic Litter (Springer, 2015), pp. i–xiv, at xii.

¹⁰³ M.G.J. Löder & G. Gerdts, ‘Methodology Used for the Detection and Identification of Microplastics: A Critical Appraisal’, in Bergmann, Gutow & Klages, ibid., pp. 201–27, at 222. So far, there is no established analytical method for detecting nanoplasitcs in the oceans: A.A. Koelmans, E. Besseling & W.J. Shim, ‘Nanoplastics in the Aquatic Environment: Critical Review’, in Bergmann, Gutow & Klages, ibid., pp. 325–40, at 330.

¹⁰⁴ South China Sea Arbitration, n. 26 above, pp. 417–8, para. 640; ICJ, Monetary Gold Removed from Rome in 1943 (Italy v. France, United Kingdom of Great Britain and Northern Ireland and United States of America), Judgment, 15 June 1954, ICJ Reports (1954), p. 19, at 32.

¹⁰⁵ In fact, the dictum was repeatedly confirmed in the jurisprudence: ICJ, East Timor (Portugal v. Australia), Judgment, 30 June 1995, ICJ Reports (1995), p. 90, at 102, para. 28.

¹⁰⁶ Ibid., pp. 104–5, paras 34–35.

¹⁰⁷ Nollkaemper et al., n. 74 above, p. 68, para. 9. In this regard, Okowa considered that ‘[i]t is difficult to see how the principle of joint or several responsibility can be applied on the international plane without offending this principle [i.e. the Monetary Gold rule]’: Okowa, P.N., State Responsibility for Transboundary Air Pollution in International Law (Oxford University Press, 2000), p. 199CrossRefGoogle Scholar.

¹⁰⁸ South China Sea Arbitration, n. 26 above, pp. 417–8, para. 640.

¹⁰⁹ Nollkaemper et al., n. 74 above, p. 69, para. 10.

¹¹⁰ See also Nedeski, n. 18 above, pp. 211–7.

¹¹¹ Nollkaemper et al., n. 74 above, p. 18.

¹¹² Ibid., p. 19.

¹¹³ Crawford, n. 11 above, p. 213.

¹¹⁴ For an analysis of various removal technologies for microplastics, see Xuan-Thanh Bui et al., ‘Microplastics Pollution in Wastewater: Characteristics, Occurrence and Removal Technologies’ (2020) 19 Environmental Technology and Innovation, pp. 1–18, at 8–13. With regard to ocean clean-up systems, see https://theoceancleanup.com/oceans.

¹¹⁵ Bui et al., ibid., p. 13; Barcelo & Pico, n. 2 above, p. 3.

¹¹⁶ Nollkaemper et al., n. 74 above, p. 19.

¹¹⁷ ICJ, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua), Compensation, Judgment, 2 Feb. 2018, ICJ Reports (2018), p. 15.

¹¹⁸ Ibid., p. 37, para. 78.

¹¹⁹ See, e.g., K. Kindji & M. Faure, ‘Assessing Reparation of Environmental Damage by the ICJ: A Lost Opportunity?’ (2019) 57 Questions of International Law, Zoom-in, pp. 5–33, at 26; J. Rudall, ‘Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua): Compensation Owed by the Republic of Nicaragua to the Republic of Costa Rica’ (2018) 112(2) American Journal of International Law, pp. 288–94, at 292; Y. Tanaka, ‘Temporal Elements in the Valuation of Environmental Damage: Reflections on the Costa Rica v. Nicaragua Compensation Case before the International Court of Justice’ (2021) 90 Nordic Journal of International Law, pp. 257–91, at 265–78.

¹²⁰ Kawasaki, n. 81 above, p. 27.

¹²¹ Gabčíkovo-Nagymarous Project, n. 33 above, p. 78, para. 140.

¹²² Costa Rica v. Nicaragua, n. 117 above, Separate Opinion of Judge Cançado Trindade, p. 65, para. 15.

¹²³ Tanaka, n. 119 above, p. 271.

¹²⁴ A similar issue may arise in climate change litigation. As Peel observed, however, ‘[t]o date, no claim has been determined at the international level based on a theory of (shared) responsibility for climate change-related injuries, or breaches of joint obligation to take action on aspects of the climate change problem’: J. Peel, ‘Climate Change’, in Nollkaemper & Plakokefalos, n. 20 above, pp. 1009–50, at 1013.

¹²⁵ ILC, n. 43 above, p. 154, para. 11.

¹²⁶ South China Sea Arbitration, n. 26 above, pp. 527–8, para. 961. See also ICJ, Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment, 20 Apr. 2010, ICJ Reports (2010), p. 14, at 83, para. 204.

¹²⁷ South China Sea Arbitration, n. 26 above, p. 542, para. 992.

¹²⁸ Responsibilities and Obligations of States Sponsoring Persons and Entities, n. 29 above, p. 48, para. 136. See also Boyle & Redgwell, n. 9 above, p. 165.

¹²⁹ See the OSPAR Convention, Paris (France), 22 Sept. 1992, in force 25 Mar. 1998, Appendix 1, paras 2 and 8, available at: http://www.ospar.org.

¹³⁰ See also Boyle & Redgwell, n. 9 above, p. 165.

¹³¹ Ibid., p. 184. By way of example, EIA is defined as ‘a national procedure for evaluating the likely impact of a proposed activity on the environment’ in Art. 1(vi) of the 1991 Convention on Environmental Impact Assessment in a Transboundary Context, Espoo (Finland), 25 Feb. 1991, in force 10 Sept. 1997, available at: https://unece.org/fileadmin/DAM/env/eia/documents/legaltexts/Espoo_Convention_authentic_ENG.pdf.

¹³² Tanaka, Y., ‘Obligation to Conduct an Environmental Impact Assessment (EIA) in International Adjudication: Interaction between Law and Time’ (2021) 90 Nordic Journal of International Law, pp. 86–121, at 93, 101CrossRefGoogle Scholar.

¹³³ Responsibilities and Obligations of States Sponsoring Persons and Entities, n. 29 above, p. 50, para. 145; Pulp Mills on the River Uruguay, n. 126 above, p. 83, para. 204; ICJ, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua) and Construction of a Road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica), Judgment, 16 Dec. 2015, ICJ Reports (2015), p. 665, at 706–7, para. 104.

¹³⁴ Tanaka, n. 132 above, pp. 92–102.

¹³⁵ There is much literature on compliance procedures; see, e.g., T. Treves et al. (eds), Non-Compliance Procedures and Mechanisms and the Effectiveness of International Environmental Agreements (TMC Asser Press, 2009); Goeteyn, N. & Maes, F., ‘Compliance Mechanisms in Multilateral Environmental Agreements: An Effective Way to Improve Compliance?’ (2011) 10 Chinese Journal of International Law, pp. 791–826CrossRefGoogle Scholar; A. Huggins, Multilateral Environmental Agreements and Compliance: The Benefits of Administrative Procedures (Routledge, 2018); Y. Tanaka, ‘Compliance Procedure (Multilateral Environmental Agreements)’, in H.R. Fabri (ed.), Max Planck Encyclopedia of International Procedural Law (MPEiPro) (online, Oxford University Press, 2021).

¹³⁶ Tanaka, ibid., para. 3.

¹³⁷ N. 66 above.

¹³⁸ Ibid., Art. 20 (1)(a) and (b).

¹³⁹ HELCOM Recommendation 42-43/3, available at: https://helcom.fi/action-areas/marine-litter-and-noise/marine-litter/marine-litter-action-plan.

¹⁴⁰ Ibid., p. 5.

¹⁴¹ N. 129 above.

¹⁴² Ibid., see also Art. 21.

¹⁴³ On 2 Mar. 2022, the UNEP Environmental Assembly decided to convene, by 2024, an intergovernmental negotiating committee to adopt a new international legally binding instrument on plastic pollution, including in the marine environment: Res. 5/14 ‘End Plastic Pollution: Towards an Internationally Binding Legal Instrument’, 2 Mar. 2022, UN Doc. UNEP/EA.5/Res.14, available at: https://wedocs.unep.org/bitstream/handle/20.500.11822/40597/Plastic_pollution_UNEP_EA.5_Res.14_EPP_EN.pdf?sequence=6&isAllowed=y. See also UNEP Press Release, ‘Historic Day in the Campaign to Beat Plastic Pollution: Nations Commit to Develop a Legally Binding Agreement’, 2 Mar. 2022, available at: https://www.unep.org/news-and-stories/press-release/historic-day-campaign-beat-plastic-pollution-nations-commit-develop. See also Stöfen-O'Brien, A., ‘The Prospects of an International Treaty on Plastic Pollution’ (2022) 37(4) The International Journal of Marine and Coastal Law, pp. 727–40CrossRefGoogle Scholar.

¹⁴⁴ C. Schmidt, T. Krauth & S. Wagner, ‘Export of Plastic Debris by Rivers into the Sea’ (2017) 51(21) Environmental Science and Technology, pp. 12246–53. According to the authors’ supporting information, mismanaged plastic waste (MMPW) and plastic loads for the top 10 ranked catchments sorted by MMPW are Chang Jian (Yangtze River), Indus, Huang He (Yellow River), Hai He, Nile, Meghna/Bramaputra/Ganges, Zhujiang (Pearl River), Amur, Niger, and Mekong. Among these rivers, international watercourses are the Amur, Ganges, Indus, Mekong, Nile, and Niger rivers.

¹⁴⁵ L. Finska & J.G. Howden, ‘Troubled Waters: Where is the Bridge? Confronting Marine Plastic Pollution from International Watercourses’ (2018) 27(3) Review of European, Comparative and International Environmental Law, pp. 245–53, at 245; Oral, n. 5 above, p. 288.

¹⁴⁶ Further, see Finska, n. 17 above, pp. 115–28.

¹⁴⁷ New York, NY (US), 21 May 1997, in force 17 Aug. 2014, available at: http://legal.un.org/ilc/texts/instruments/english/conventions/8_3_1997.pdf; see Arts 20 and 22.

¹⁴⁸ Helsinki (Finland), 17 Mar. 1992, in force 6 Oct. 1996, available at: http://www.unece.org/env/water.

¹⁴⁹ Bern (Switzerland), 12 Apr. 1999, in force 1 Jan. 2003, available at: https://www.iksr.org/fileadmin/user_upload/DKDM/Dokumente/Rechtliche_Basis/EN/legal_En_1999.pdf.

¹⁵⁰ ICPR, ‘“RHINE 2040” Programme: The Rhine and its Catchment: Sustainably Managed and Climate-Resilient’, 13 Feb. 2020, p. 17, available at: https://www.iksr.org/fileadmin/user_upload/DKDM/Dokumente/Sonstiges/EN/ot_En_Rhine_2040.pdf.

¹⁵¹ Ibid.

¹⁵² Ibid., p. 24.

¹⁵³ OSPAR Commission, ‘Observers’, available at: https://www.ospar.org/organisation/observers.

¹⁵⁴ Memorandum of Understanding between the International Commission for the Protection of the Black Sea (ICPBS) and the International Commission for the Protection of the Danube River (ICPDR) on Common Strategic Goals, available at: http://www.icpdr.org/main/resources/mou-between-icpbs-and-icpdr.