1 As per arts 74(1) and 83(1) of the UN Convention on the Law of the Sea 1982, signed 10 December 1982 and entered into force 16 November 1994.

2 See Rosenne, S “Geography in international maritime boundary-making” in Caminos, H (ed) Law of the Sea (2001, Ashgate Publishing) 225 at 226–27Google Scholar.

3 UN General Assembly res 1803 (XVII) on permanent sovereignty over natural resources, 14 December 1962; UN General Assembly res 3281 (XXIX) Charter on Economic Rights and Duties of States, 12 December 1974.

4 This customary rule has been attributed to the remark of Cornelius van Bynkershoek in 1702, that “territorial sovereignty ends where the power of arms ends”. The 3 nm limit remained fixed for the next two centuries. LBrilmayer and N Klein “Land and sea: Two sovereignty regimes in search of a common denominator” (2001, Yale Law School Faculty scholarship paper 2523) 706 at 717; Walker, W “Territorial waters: The cannon shot rule” (1945) 22 British Yearbook of International Law 210 at 211–13Google Scholar.

5 See of US President Harry Truman's Proclamation with Respect to the Natural Resources of the Subsoil and the Seabed of the Continental Shelf and Proclamation with Respect to Coastal Fisheries in Certain Areas of the High Seas, 28 September 1945; Proclamation of Argentina on the Epicontinental Sea, 5 December 1946; Declaration of the Maritime Zone of Chile, Ecuador and Peru (Santiago Declaration), 18 August 1952.

6 Signed 29 April 1958, and entered into force 10 June 1964, arts 1–2.

7 UNCLOS, arts 3, 57 and 76, respectively.

8 The determination of a boundary line by treaty or otherwise is called delimitation, while the actual laying down of this line and its definition by boundary pillars or other similar means is called demarcation. Sir H McMahon “International boundaries” (1935) 84 Journal of the Royal Society of Arts 1 at 4.

9 See definition in Oxford Dictionaries, available at: <http://www.oxforddictionaries.com/definition/english/boundary> (last accessed 27 August 2017).

10 Johnston, D Theory and History of Boundary-Making (1998, McGill-Queen's University Press) at 42Google Scholar.

11 Id at 12. Also see Prescott, V and Schofield, C Political Boundaries of the World (2004, Martinus Nijhoff) at 216–17Google Scholar.

12 North Sea Continental Shelf cases (Federal Republic of Germany v Denmark; Federal Republic of Germany v Netherlands) (1969) ICJ Rep 3 at 46.

13 The fact that states are not required to delimit their maritime spaces in order to exercise offshore jurisdiction is also confirmed by their right to explore their shared natural resources, pending delimitation, through a joint development agreement.

14 Johnston Theory and History, above at note 10 at 10.

15 Pan, J Toward a New Framework for Peaceful Settlement of China's Territorial and Boundary Disputes (2009, Martinus Ninjhoff) at 23CrossRefGoogle Scholar; Merrills, J “The means of dispute settlement” in Evans, M (ed) International Law (2003, Oxford University Press) 528 at 530Google Scholar.

16 Pan, id at 24.

17 For example, it is supported that the long maritime disputes between Greece and Turkey in the Aegean Sea, China and Japan in the East China Sea or China, the Philippines and Vietnam in the South China Sea threaten global peace and stability. The same applies on land. In Africa, for example, three major wars (Biafra, Eritrea, the Ogaden) and the civil wars in Chad and Sudan have all been caused by territorial disputes. Similarly, in the Middle East, five wars arose from the failure of Jewish and Arab occupants of Palestine to agree on a mutual boundary. See D Downing An Atlas of Territorial and Border Disputes (1980, New English Library) at 9.

18 UN Charter, chap VI, art 33.1.

19 UNCLOS, preamble and arts 279–80.

20 “Although it is true that the act of delimitation is necessarily a unilateral act, because only the coastal State is competent to undertake it, the validity of the delimitation with regards to other States depends upon international law”: Fisheries case (United Kingdom v Norway) [1951] ICJ Rep 116 at 132.

21 UNCLOS, art 283.

22 Id, arts 286–87. However, under neither the UN Charter nor general international law are states obliged to exhaust diplomatic negotiations before bringing their maritime dispute to an international court or tribunal: Cameroon v Nigeria judgment on preliminary objections, ICJ Rep 1998, 303, para 56.

23 I Karaman Dispute Settlement Under the Law of the Sea Convention (2012, Martinus Nijhoff) at 184.

24 North Sea Continental Shelf cases, above at note 12 at 93.

25 Dissenting opinion in The Mavrommatis Palestine Concessions (1924) PCIJ ser A, no 2 at 62.

26 “The chance of success of diplomatic negotiations is essentially a relative one”: id at 13. China and Japan, for example, had 13 unsuccessful rounds of negotiation regarding the delimitation of the East China Sea.

27 A list of disputes submitted to adjudication can be found on the official websites of the ICJ and arbitral tribunals, available at: <http://www.icj-cij.org/en/cases> (last accessed 14 September 2017) and <https://www.itlos.org/en/cases/> (last accessed 27 August 2017) respectively.

28 A Cukwurah The Settlement of Boundary Disputes in International Law (1967, Manchester University Press) at 200.

29 As in the North Sea Continental Shelf cases, above at note 12.

30 As in the application for maritime delimitation in the Caribbean Sea and the Pacific Ocean (Costa Rica v Nicaragua), filed at the ICJ on 25 February 2015.

31 P Weil The Law of Maritime Delimitation: Reflections (1989, Grotius Publications) at 48.

32 North Sea Continental Shelf cases, above at note 12 at 91.

33 Id at 22.

34 For example: Guyana in the waters also claimed by Suriname; Ukraine in the area of the Black Sea claimed by Romania; Tunisia and Libya, Libya and Malta in the respective maritime disputes in the Mediterranean Sea; China and Japan in the East China Sea; China and Vietnam in the South China Sea; and Greece and Turkey in the Aegean Sea.

35 North Sea Continental Shelf cases, above at note 12 at 57 and 101; Maritime Delimitation in the Area between Greenland and Jan Mayen (Denmark v Norway) (1993) ICJ Rep 38 at 59; Weil The Law of Maritime Delimitation, above at note 31 at 3.

36 Insofar as the state's exploratory activities do not cause permanent change to the seabed (such as drilling). For example, the unilateral conduct of seismic surveys (with the use of ultrasound waves) is permissible. Guyana/Suriname arbitral award (PCA 2007) ICGJ at 465–67 and 470; Aegean Continental Shelf case (Greece v Turkey) request for the indication of interim measures of protection (1976) ICJ Rep 3 at 30–33.

37 See Maritime Delimitation in the Black Sea (Romania v Ukraine) (2009) ICJ Rep 61; Guyana/Suriname (ibid); Case Concerning the Land and Maritime Boundary between Cameroon and Nigeria (Cameroon v Nigeria: Equatorial Guinea intervening) ICJ Rep 2002.

38 “Whether it is a land frontier or a boundary line in the continental shelf that is in question, the process is essentially the same, and inevitably involves the same element of stability and performance”: Aegean Sea Continental Shelf (Greece v Turkey) (1978) (jurisdiction of the court) ICJ Rep 3 at 35–36. Similarly, in 1982, Judge Juménez de Aréchaga highlighted the “need to maintain consistency and uniformity in the legal principles and rules applicable to a series of situations which are characterised by their multiple diversity”: Continental Shelf (Tunisia v Libya) (1982) ICJ Rep 18, separate opinion at 26.

39 Continental Shelf (Libyan Arab Jamahiriya v Malta) (1985) ICJ Rep 13; Maritime Delimitation and Territorial Questions between Qatar and Bahrain (Qatar v Bahrain) merits (2001) ICJ Rep 40; Romania v Ukraine, above at note 37; Dispute Concerning Delimitation of the Maritime Boundary between Bangladesh and Myanmar in the Bay of Bengal (Bangladesh/Myanmar) (2012) ITLOS.

40 Romania v Ukraine, id at 116. Such reasons could be the existence of a boundary agreement between the disputants or an historic title.

41 For example, see Guyana/Suriname, above at note 36 at 377.

42 Arbitral Award in the Matter of Delimitation of a Certain Part of the Maritime Boundary between Norway and Sweden (Norway/Sweden) (1909) 11 RIAA XI at 6.

43 Above at note 38 at 107.

44 Id at 96.

45 Id at 118 and 133 B4.

46 Case Concerning Delimitation of the Maritime Boundary in Gulf of Maine (Canada v USA) (1984) ICJ Rep 246 at 149–54; Delimitation of the Maritime Boundary between Guinea and Guinea Bissau (1985) award at 62–63 and 105; Delimitation of Maritime Areas between Canada and the French Republic (St Pierre et Miquelon) (1992) arbitral award at 89–91; arbitration between Newfoundland and Labrador and Nova Scotia, award of arbitral tribunal (2002) at 3.4; Cameroon v Nigeria, above at note 37 at 304; arbitration between Barbados and Trinidad and Tobago (2006) award at 361–64; Territorial and Maritime Dispute between Nicaragua and Honduras in the Caribbean Sea (Nicaragua v Honduras) (2007) ICJ Rep 659 at 247 and 253–58; Guyana / Suriname, above at note 36 at 390; Romania v Ukraine, above at note 37 at 198.

47 See dissenting opinions by Judges Gros and Oda. Also see Cottier, T Equitable Principles of Maritime Boundary Delimitation (2015, Cambridge University Press) at 284CrossRefGoogle Scholar.

48 Tanaka, Y International Law of the Sea (2012, Cambridge University Press) at 211CrossRefGoogle Scholar; Tunisia v Libya, above at note 38, dissenting opinion of Judge Evensen at 318–19.

49 North Sea Continental Shelf cases, above at note 12 at 19.

50 Lagoni, R “Oil and gas deposits across national frontiers” (1979) 73/2 The American Journal of International Law 215 at 219CrossRefGoogle Scholar.

51 E Vattel The Law of Nations or the Principles of Natural Law, Applied to the Conduct and to the Affairs of Nations and of Sovereigns (transl of the 1758 ed by C Fenwick, 1916, Carnegie Institution of Washington) book III, chap XIII at 200–01. Also see Certain Questions Relating to Settles of German Origin in the Territory Ceded by Germany to Poland (German Settles) (1923) PCIJ (ser B) no 6 at 36; Case Concerning Certain German Interests in Polish Upper Silesia (1926) PCIJ (ser A) no 7 at 42.

52 Maritime Delimitation in the Indian Ocean (Somalia v Kenya), appln filed by Somalia to the ICJ on 28 August 2014, at 33.

53 Id at 19.

54 According to secs 4.3 and 6.2(1) of the Petroleum (Exploration and Production) Act (cap 308) 1986, Kenya's petroleum operations are conducted through its National Oil Company, by entering into petroleum agreements with international oil companies or in any other appropriate manner. A PSC is a contract under which a private oil company (contractor) is hired by a government (state) in order to render exploratory and financial services in a specific area (oil block). In exchange, the contractor receives a share of any oil production that may result from his work. If no production follows, the contractor receives no compensation at all. Under this regime, the state preserves ownership of its resources and compensates (in a production share) the contractor for undertaking the sole risk of upstream operations. In that sense, a PSC is a service (or work) contract with payment in kind. See B Taverne Petroleum Industry and Governments (2nd ed, 2008, Kluwer International Law) at 156; Easo, J “Petroleum contracts: Licenses, concessions, production sharing agreements and service contracts” in Picton-Turbervill, G Oil and Gas: a Practical Handbook (2nd ed, 2014, Globe Law and Business) 7 at 15Google Scholar; Jennings, A Oil and Gas Exploration Contracts (2nd ed, 2008, Sweet & Maxwell) at 2Google Scholar.

55 Blocks L-21, L-23 and L-24 were awarded for exploration to Eni in 2012, while L-22 was awarded to Total in the same year. Statoil showed interest in L-26 but eventually decided to avoid the area. The Norwegian government commented that “it has always advised Statoil not to apply for concessions in any areas of a potential legal dispute, and when realizing that this was the case with the mentioned L-26 block, Statoil decided not to get involved”. Anadarko received L-5 in 2010 but, according to subsequent reports, gave up its interest in late 2012 or early 2013, while L-25 remains under negotiation. See Somalia's application to the ICJ at 6 and: “Eni's operations in Africa”, available at: <http://www.eni.com/portal/search/search.do?x=0&y=0&keyword=kenya&locale=en_IT&header=search> (last accessed 27 August 2017); “Total steps up exploration activities in Kenya with the award of the offshore L22 license in the Lamu Basin” (press release, 27 June 2012), available at: <http://www.total.com/en/media/news/press-releases/total-steps-exploration-activities-kenya-award-offshore-l22-license-lamu?xtmc=kenya&xtnp=1&xtcr=2> (last accessed 27 August 2017); and Norwegian Ministry of Foreign Affairs “Norway regrets claims by a UN report linking Norwegian development efforts to commercial interests in Somalia” (19 July 2013), available at: <https://www.regjeringen.no/en/aktuelt/development-efforts-somalia/id732864/> (last accessed 27 August 2017).

56 In 2012, Somalia's deputy energy minister, Abdullahi Dool, stated that the “contracts awarded by Kenya for four blocks in deep waters were invalid and the government planned to complain to the United Nations, which oversees maritime border laws”: “Somalia challenges Kenya over oil blocks” (6 July 2012) Reuters, available at: <http://uk.reuters.com/article/2012/07/06/kenya-somalia-exploration-idUSL6E8I63IM20120706> (last accessed 27 August 2017).

57 Somalia's application to the ICJ at 36.

58 The states’ coasts are neither concave nor convex.

59 The signed contracts are not publicly available, hence this article refers to Kenya's Model PSC of 2008: National Oil Corporation of Kenya “Overview of legal framework” (Model PSC), available at: <http://www.nationaloil.co.ke/site/3.php?flag=upstream&id=10> (last accessed 27 August 2017). According to clause 40 of the Model PSC, the contract is governed by the laws of Kenya. According to art 2 of Kenya's Law of Contract cap 23, 1961 “the common law of England relating to contract … shall extend and apply to Kenya”.

60 This position was supported in several arbitral awards. See Texaco Overseas Petroleum Co (Topco) and California Asiatic (Calasiatic) Oil Company v the Government of Libyan Arab Republic award (1977) 53 ILR 389; Libyan American Oil Company (Liamco) v the Government of the Libyan Arab Republic (1977) 62 ILR 141. The opposite opinion is expressed by M Maniruzzaman “State contracts with aliens: The question of unilateral change by the state in contemporary international law” (1992) 9/4 Journal of International Arbitration 141 at 141.

61 J Morgan Great Debates in Contract Law (2012, Palgrave MacMillan) at 120.

62 Taylor v Caldwell [1863] 3 B&S 826 at 833.

63 Sir D Hughes Parry Sanctity of Contracts in English Law (1959, Stevens & Sons) at 47.

64 Lord Wright, cited in Treitel, G Frustration and Force Majeure (2nd ed, 2004, Sweet & Maxwell) at 2-045Google Scholar.

65 Metropolitan Water Board v Dick, Kerr and Co [1918] AC 119; Walton Harvey Ltd v Walker and Homfrays Ltd [1931] 1 Ch 274. An event caused by the parties’ deliberate acts or negligence is not frustrating: Treitel, id at 14-003. As similarly held in Kenya's courts: “a frustrating event must be some outside event or extraneous change of situation … [It] must take place without blame or fault on the side of the party seeking to rely on it”: Samuel Chege Gitau and Another v Joseph Gicheru Muthiora [2014] eKLR, available at: <http://kenyalaw.org/caselaw/cases/view/105926/> (last accessed 14 September 2017), citing J Lauritzen AS v Wijsmuller BV (The Super Servant Two) [1990] 1 Lloyd's Rep 1 at 8; Gimal u Estates Ltd and Four Others v International Finance Corp and Another [2006] eKLR, available at: <http://kenyalaw.org/caselaw/cases/view/19652> (last accessed 14 September 2017).

66 Lord Radcliffe in Davis Contractors LTD v Fareham Urban District Council [1956] AC 696 at 729.

67 Yates, D “Drafting force majeure and related clauses” (1991) 3 Journal of Contract Law 186 at 191Google Scholar; Simonds, Lord Halsbury's Laws of England vol 8 (3rd ed, 1954, Butterworths) at 185Google Scholar. According to McElroy, the same applies for “commercial impossibility”: McElroy, RG Impossibility of Performance (1941, Cambridge University Press) at 194Google Scholar.

68 Lord Denning MR in Ocean Tramp Tankers Corp v V/O Sovfracht (The Eugenia) [1964] 2 QB 226 at 239.

69 Above at note 62 at 829.

70 BP Exploration Co (Libya) Ltd v Hunt [1983] 2 AC 352.

71 Peckham v Industrial Securities Co 113 A 799 (1929).

72 Treitel Frustration, above at note 64 at 4-001.

73 Hence, the redistribution of the contract area could be considered as a case of “supervening illegality”, which also causes frustration. See McKendrick, E Contract Law (5th ed, 2012, Oxford University Press) at 723Google Scholar.

74 Treitel, G The Law of Contract (10th ed, 1999, Sweet & Maxwell) at 841Google Scholar.

75 UNCLOS, arts 15, 74.1 and 83.1.

76 Id, arts 74.2 and 83.2.

77 Aegean Continental Shelf case, above at note 36 at 27–31.

78 Pan Toward a New Framework, above at note 15; Merrills “The means of dispute settlement”, above at note 15.

79 K Gilblom “Kenya, Somalia border row threatens oil exploration” (20 April 2012) Reuters, available at: <http://www.reuters.com/article/2012/04/20/us-kenya-exploration-idUSBRE83J0M120120420> (last accessed 27 August 2017).

80 “MoU signed between the Government of the Republic of Kenya and the Transitional Federal Government (TFG) of the Somali Republic granting to each other no-objection in respect of submissions on the outer limits of the continental shelf beyond 200 nm to the Commission on the Limits of the Continental Shelf”, available at: <http://www.innercitypress.com/los2somalia.pdf> (last accessed 27 August 2017). It was also added that delimitation of the shared area would be agreed between the states on the basis of international law after receiving the commission's recommendations. According to the UN however, the MoU was eventually rejected by the Parliament of the TFG and is therefore treated as “non-actionable”. See UN Records, Legislation and Treaties “Kenya”, available at: <http://www.un.org/depts/los/LEGISLATIONANDTREATIES/STATEFILES/KEN.htm> (last accessed 14 September 2017), stating: “By a note verbale dated 2 March 2010, the Permanent Mission of the Somali Republic to the United Nations informed the Secretariat that the MOU had been rejected by the Parliament of the Transitional Federal Government of Somalia, and ‘is to be hence treated as non-actionable’.” Also see UN Division for Ocean Affairs and Law of the Sea “Preliminary information indicative of the outer limits of the continental shelf beyond 200 nautical miles”, available at: <http://www.un.org/Depts/los/clcs_new/commission_preliminary.htm#%282%29_> (last accessed 27 August 2017).

81 See Walton v Walker, above at note 65 at 282.

82 Nile Co for the Export of Agricultural Crops v H and JM Bennet (Commodities) Ltd [1963] 1 Lloyd's Rep 555 at 582; Treitel Frustration, above at note 64 at 13-001.

83 Treitel, id at 13-008.

84 Art 1148 of the French Civil Code reads, “there is no place for any damages when, as a result of force majeure or cas fortuit, the debtor has been prevented from conveying or doing that to which he was obliged or has done what was forbidden to him”. Swadling, W “The judicial construction of force majeure clauses” in McKendrick, E (ed) Force Majeure and Frustration of Contract (2nd ed, 1995, Lloyd's of London Press Ltd) 1 at 6Google Scholar.

85 Although force majeure can be a contractual clause, it has been held that it is a general principal of law applicable even when the contract is silent on that point: Mobil Oil Iran Inc v Government of the Islamic Republic of Iran, Iran-US CTR award no 311-74/76/81/150-3 (1987) 39; Phillips Petroleum Co Iran v Islamic Republic of Iran, Iran-US CTR award no 425-39-2 (1989) 108.

86 Swadling “The judicial construction”, above at note 84 at 8.

87 Id at 5.

88 Model PSC, clause 38.

89 Swadling “The judicial construction”, above at note 84 at 18.

90 Id at 9; Model PSC, clause 38.6.

91 Model PSC, clause 38.5.

92 McKendrick Contract Law, above at note 73 at 44.

93 However, even if maritime delimitation was explicitly referred to in the force majeure clause, that would not exclude the doctrine of frustration. See McKendrick, id at 34. The opposite was expressed by Mocatta J in Bremer Handelsgesellschaft mbH v Vanden Avenne-Izegem PVBA [1977] 1 Lloyd's Rep 133 at 163.

94 Of course Kenya may redesign its reduced oil blocks and sign new PSCs with the same or different investors.

95 Treitel Frustration, above at note 64 at 5-008.

96 The Super Servant Two, above at note 65 at 8.

97 Unless they obtain a permit from Somalia after delimitation.

98 Paul Kipsang Kosgei and Two Others v Thomas Kprono Magut and Another [2014] eKLR, available at: <http://kenyalaw.org/caselaw/cases/view/100597/> (last accessed 14 September 2017).

99 Model PSC, clauses 4.6 and 5.

100 R Halson Contract Law (2001, Pearson Education) at 427. One might argue that Kenya's investors are entitled to “equitable relief” on the basis of “proprietary estoppel”. In English common law, this is triggered when a person is given a clear assurance (such as an oral promise) that they will acquire a right over property and they suffer detriment as a result of their reliance on this assurance. See Taylor Fashions and Old & Campbell v Liverpool Victoria Trustees [1982] QB 133. However, this is not the case here, as the parties have signed a contract (the PSC).

101 R Goff and G Jones The Law of Restitution (7th ed, 2008, Sweet & Maxwell Ltd) at 19-002.

102 Blakeley v Muller & Co [1903] 2 KB 760n; Chandler v Webster [1904] QKB 493.

103 Fibrosa Spolka Akcyjna v Fairbairn Lawson Combe Barbour Ltd [1943] AC 32 at 48; Whincup v Hughes (1870–71) LR 6 CP 78 at 84.

104 A Hussain General Principles and Commercial Law of Kenya (1993, East African Publishers) at 8; schedule of Kenya's Law of Contract cap 23, 1961.

105 A Burrows The Law of Restitution (2nd ed, 2002, Butterworths) at 362; Law Reform (Frustrated Contracts) Act 1943, sec 1(1).

106 Id, sec 1(3).

107 Ranfer Company Ltd v Commissioner of Customs & Excise and Another [2003] eKLR, available at: <http://kenyalaw.org/caselaw/cases/view/4049/> (last accessed 14 September 2017).

108 Model PSC, clauses 14(2) and 15.

109 [1979] 1 WLR 783.

110 Id at 799.

111 Id at 802.

112 Id at 802–03.

113 Id at 805.

114 Subject to the exceptions in sec 1(5) of the act.

115 Clause 41 of the Model PSC reads: “Any question or dispute arising out of or in relation to or in connection with this contract shall, as far as possible, be settled amicably. Where no settlement is reached within 30 days from the date of the dispute … the dispute shall be referred to arbitration in accordance with the UNCITRAL arbitration rules adopted by the United Nations Commission on International Trade Law.”

116 In 2012, the East African Energy Forum warned Kenya's investors (Eni, Total, Statoil and Anadarko) about the “risk of being shut out of future Somali energy concessions”, along with what it described as “legal action” that might be taken against Kenya and the oil companies. See “International oil companies illegally exploiting Somali hydrocarbons?” (23 August 2012) OilPrice.com, available at: <http://oilprice.com/Latest-Energy-News/World-News/International-Oil-Companies-Illegally-Exploiting-Somali-Hydrocarbons.html> (last accessed 27 August 2017). In September 2013, however, the president of Federal Republic of Somalia met Eni's CEO in “an atmosphere of cordiality” to discuss “Eni's interest in evaluating the exploration potential of hydrocarbons present in Somalia”; see “Somalia's president and Eni's Paolo Scaroni discuss energy” MarineLink, available at: <https://www.marinelink.com/news/maritime/eni-exploration> (last accessed 14 September 2017).

117 As in art 6 of the delimitation treaty between Equatorial Guinea and Nigeria, 23 September 2000.

118 For example, see joint development agreements entered into between Kuwait and Saudi Arabia on 7 July 1965, and Japan and the Republic of Korea on 30 January 1974.

119 For discussion of the merits and challenges of joint development, see Schofield, C “No panacea? Challenges in the application of provisional arrangements of a practical nature” in Nordquist, M and Moore, J Norton (eds) Center for Oceans Law and Policy, Vol 16: Maritime Border Diplomacy (2012, Martinus Nijhoff) 151Google Scholar.

120 For example, the British-Norwegian Agreement relating to the Exploitation of the Frigg Field Reservoir, 10 May 1976; Framework Agreement between the United Kingdom and Norway, 4 April 2005.

121 North Sea Continental Shelf cases, above at note 12 at 97–101; Eritrea / Yemen, award of the arbitral tribunal, second stage (1999) at 84–86; Tunisia v Libya, above at note 38, Judge Evensen's dissenting opinion at 321–23; Guinea / Guinea-Bissau, above at note 46 at 121–23.

122 For instance, the tribunal in Eritrea / Yemen did not refer to states’ general obligation to cooperate post delimitation. Rather, it focused on the behaviour of the particular disputants. According to some scholars however, the tribunal's position on common exploration of transboundary resources may eventually suggest the introduction of a custom. See Cottier Equitable Principles, above at note 47 at 367; and Reisman, M “Eritrea-Yemen arbitration (award, phase II: Maritime delimitation)” (2000) 94 American Journal of International Law 721 at 735CrossRefGoogle Scholar.

123 For discussion of the merits and challenges of unitization, see I Townsend-Gault “Zones of cooperation in the oceans: Legal rationales and imperatives” in Nordquist and Norton Moore Maritime Border Diplomacy, above at note 119, 110 at 110–33.