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The Principle of Non-Encroachment: Implications for the Beaufort Sea*

  • Roger Gillott (a1)


Ce commentaire traite des principes connexes de prolongement naturel et de non-empiètement et de leurs conséquences sur une future délimitation de la frontière maritime entre le Canada et les États-Unis dans la Mer de Beaufort. L'auteur décrit l'évolution du principe du prolongement naturel, qui reposait d'abord sur la géologie et la morphologie du plateau continental pour se définir maintenant en grande partie par les concepts de distance et de proximité. L'auteur constate aussi que, même si le non-empiètement n'est pas une règle de délimitation mécanique et contraignante, il est devenu un principe équitable qui est rarement ou pour ainsi dire jamais supplanté par des principes équitables concurrents. Par conséquent, la direction de la projection côtière est devenue un aspect capital de toute délimitation. L'auteur discute ensuite de l'impact de ces conclusions sur la délimitation de la Mer de Beaufort.


This comment deals with the related principles of natural prolongation and non-encroachment and their implications for any future delimitation of the maritime boundary between Canada and the United States in the Beaufort Sea. The evolution of the principle of natural prolongation is traced from one based in the geology and geomorphohgy of the continental shelf to one based primarily on concepts of distance and proximity. The conclusion is reached that, while not a binding or mechanistic rule of delimitation, non-encroachment is an equitable principle that is rarely if ever superseded by competing equitable principles. For this reason, the direction of the coastal projection has become a key aspect of any delimitation, including the Canada/United States negotiations on the Beaufort Sea.



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The author would like to thank Professor Judith Swan for her helpful advice and Professor Ian Brownlie and Dr. Christine Gray whose seminars and materials inspired an interest in this subject.



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1 Kindred, Hugh, M. et al., International Law, Chiefly as Interpreted and Applied in Canada 716 (5th ed., Toronto: Emond Montgomery, 1993).

2 Rothwell, D., Maritime Boundaries and Resource Development: Options for the Beaufort Sea 25–30 (Calgary: The Canadian Institute of Resource Law, 1988).

3 Ibid. Fisheries in the Beaufort Sea area are relatively unimportant due to a lack of commercial exploitation. See Lawson, Karin L., “Delimiting Continental Shelf Boundaries in the Artic: The U.S.-Canada Beaufort Sea Boundary,” (1981) 22 Va. J. Int’l L. 221 at 227.

4 Bergman, Brian et al., “Parting the Waters,” Maclean’s (Aug. 12, 1991) 14.

5 As demonstrated by the negotiations regarding the Gulf of Maine dispute: Kindred, supra note 1 at 719.

6 On the issues of the treaties of 1825 and 1867, the sector theory, equidistance, and claims of U.S. acquiescence, see Lawson, supra note 3; Pharand, D., Canada’s Arctic Waters in International Law 17, 18 (Cambridge: Cambridge University Press, 1988); Prescott, J.R.V., The Maritime Political Boundaries of the World 268 (New York: Methuen, 1985); and Rothwell, supra note 2. On historic Inuit usage of the area, see VanderZwaag, D. and Pharand, D., “Inuit and the Ice: Implications for Canadian Arctic Waters” (1983) 21 Canadian Yearbook of International Law 53. On the possibilities for commercial and environmental joint development zones, see Lamson, C. and VanderZwaag, D., “Arctic Waters: Needs and Options for Canadian — American Cooperation” (1987) Ocean Dev. & Int’l L. 49.

7 (1910) 4 Am. J. Int’l L. 226 at 231.

8 [1969] ICJ Rep. 4.

9 Ibid., para. 101.

10 Ibid., para. 8.

11 Ibid., paras 95–96.

12 Ibid., para. 45.

13 Ibid., paras. 8, 42–45.

14 Such as concave coastlines or where small islands are located close to mainland shores.

15 (1977) 54 I.L.R. 6.

16 Ibid., paras. 104s–109.

17 Ibid., paras. 191–92.

18 Ibid., paras. 175–88.

19 (1982) ICJ Rep. 3; see Map 2.

20 Technically speaking, the court was asked to define the applicable principles and rules, but in fact a line did result from its conclusions.

21 Supra note 19, paras. 61–68.

22 Ibid., para. 44.

23 Ibid.

24 Separate Opinion of Judge ad hoc Jiménez de Arechaga; ibid., 102–105.

25 Ibid., 111–12.

26 Ibid., 109–10.

27 Supra note 19, paras. 118–19.

28 Half-effect was also given to the Kerkennah Islands.

29 (1984) 71 I.L.R. 58.

30 United Nations Convention on the Law of the Sea (New York: UN Documents, 1982); Churchill, R.R. and Lowe, A.V. The Law of the Sea 133–38 (2nd ed., Manchester: Manchester University Press, 1988).

31 See Map 2.

32 Supra note 29, paras. 194–96.

33 Ibid, paras. 102–103.

34 Ibid., paras. 108–109.

35 Ibid. paras 194–96.

36 Ibid. para. 110.

37 Ibid. paras 110–12.

38 (1985) I.C.J. Rep. 13.

39 Ibid. para. 34.

40 Ibid. para. 77.

41 Ibid. para. 46.

42 (1985) 77 I.L.R. 636.

43 Ibid. at 679–81.

44 Supra note 38, para. 49.

45 Ibid, at 685–87.

46 (1992) I.L.M. 1149.

47 Ibid. paras 66–74.

48 Ibid. paras 46–47.

49 Ibid. paras 60 and 80, and citing Libya/Malta supra note 38, para. 49.

50 See the dissenting opinion of Prosper Weil in the Saint-Pierre and Miquelon case supra note 46.

51 See Libya/Tunisia, supra note 19, para. 119.

52 These are, Uruguay-Brazil, Brazil-France, Senegal/Guinea-Bissau, Umm al Quaiwan-Sharjah, and Dubai-Abu Dhabi: Allan, Willis, L.Delimitation in State Practice Generally;” in Pharand, D. and Leanza, U. (eds), The Continental Shelf and The Exclusive Economic Zone: Delimitation and Legal Regime, 6579 (The Netherlands: Kluwer, 1993).

53 Ibid. Columbia-Panama, Columbia-Honduras, Kenya-Tanzania, and Chile-Argentina. See also the U.S./Russia maritime boundary in the Bering Sea.

54 Supra note 7.

55 Ibid, at 232.

56 Supra note 29.

57 Ibid, paras 207–14.

58 Ibid, paras 224–28.

59 (1981) 91 I.L.R. 543.

60 Supra note 42.

61 Ibid.

62 In the similar enclave situations of the North Sea Continental Shelf Cases and the Nicaragua-Honduras (Gulf of Fonseca) case ((1992) I.C.J. Reports 351), while it was not practical for the court to adopt perpendiculars, the “enclaved” state was granted an enhanced form of coastal projection to ensure some seaward reach.

63 Supra note 46.

64 Ibid.

65 Ibid., appendix following the report.

66 Pharand, supra note 6 at 1–79.

67 Ibid, at 39.

* The author would like to thank Professor Judith Swan for her helpful advice and Professor Ian Brownlie and Dr. Christine Gray whose seminars and materials inspired an interest in this subject.

The Principle of Non-Encroachment: Implications for the Beaufort Sea*

  • Roger Gillott (a1)


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