I. Introduction
In August 2021, the Leaders of the Pacific Islands Forum (PIF) issued the Declaration on Preserving Maritime Zones in the Face of Climate Change-Related Sea-Level Rise,Footnote 1 stating the intention that their maritime zones, and rights and entitlements flowing from those zones, would be maintained notwithstanding the effects of sea-level rise. The position articulated by these States is not new; it is consistent with similar regional statements made over preceding decades,Footnote 2 as well as statements from individual Pacific countries at the international level.Footnote 3 However, it is at odds with the widely-expressed scholarly view that, in general, baselines and associated maritime zones ‘ambulate’ with the coastline, so that if a coastline recedes as the sea-level rises, the baseline recedes with it, potentially causing a shrinking of the maritime zones drawn from that baseline. In this context, should the PIF Declaration be viewed as a radical claim for legal stability? This article contends that it should not, offering two arguments in support.
The first argument is signalled by the PIF Declaration itself, which situates its position on the maintenance of baselines and maritime zones by reference to ‘the principles of legal stability, security, certainty and predictability that underpin the Convention and the relevance of these principles to the interpretation of the Convention in the context of sea-level rise and climate change’.Footnote 4 The PIF Declaration directs our attention inwards, pointing to the existing international legal framework, and specifically, the UN Convention on the Law of the Sea.Footnote 5 So rather than turning to options to amend this legal framework—or even to suggest a new oneFootnote 6—this article pauses to reconsider the extent to which the current legal regime reflected in the LOSC might already provide a basis for responding to sea-level rise impacts. The article argues that the stability of the legal order of maritime zones is a long-standing value of the LOSC system, evident throughout its development and increasingly invoked by States in connection with sea-level rise impacts.
The second argument offers evidence that many States have pursued stability in very practical ways, namely in how they have implemented the baseline provisions of the LOSC in domestic frameworks. The article argues that general acceptance of a diversity of methods among States in the implementation of baselines—including methods which have a stabilising effect—tends to suggest that the existing international law does accommodate the legal stability of maritime zones, at least to this extent.
Part II briefly introduces the legal framework for this article's focus on unilateral maritime zones, arguing that legal stability in this context remains understudied. While jurisprudence and scholarship on maritime boundaries illuminates some legal rules promoting stability, such rules do not readily translate from an inter-State context (ie an adjudicated boundary, or a maritime boundary treaty) to the situation of unilaterally-declared maritime zones. Furthermore, the logic underpinning the ‘ambulatory’ theory of baselines—widely-held amongst scholars—tends to leave the notion of legal stability in a conceptual blind spot.
To advance the first argument that legal stability is a long-standing value of the LOSC system, Part III asks the question: what do States say about legal stability in connection with maritime zones? It analyses the views of States at two key points in time—during the negotiation of the LOSC, and in the period 2017–2021 in the context of international discussions on sea-level rise—to consider the ways in which States have articulated a concern for legal stability. Across both time periods, States not only affirm the importance of the stability of the zonal legal order, but also draw attention to a more concrete understanding of the term ‘legal stability’ as it applies to maritime zones in the context of sea-level rise.
To advance the second argument that States pursue legal stability in the way they implement baselines, Part IV asks the question: what do States do when they implement their baselines? A case study of domestic legislation on the normal baseline (the most commonly used type of baseline) finds that most definitions of the normal baseline have some degree of stability, with the result that the baseline maintains its location on the surface of the earth over time.
These findings matter not only for how we might receive the PIF Declaration, but also, as argued in Part V, because they pose a challenge to the ability of the ‘ambulatory’ theory to provide a full account of the law, thus prompting a reconsideration of our overall conception of that law. Recognising the importance of legal stability to States, and understanding how this is complemented by action, provides a firm foundation for reassessing how the LOSC should be interpreted now and in the future.
II. The LOSC FrameworkFootnote 7 for Unilateral Maritime zones
The international law of the sea draws a close nexus between the sea and the land in the sense that a coastal State's maritime entitlements flow from its sovereignty over land. This is reflected in the terms of the LOSC, since it is ‘coastal States’ (rather than all States) which have entitlements to maritime zones adjacent to their land territory, and also in the well-known principle that ‘the land dominates the sea’.Footnote 8 The term ‘baseline’ refers to a juridical concept that has strong links to a particular part of land: the coast. A baseline is ‘the legal expression of the coast’,Footnote 9 and certain physical characteristics of that coast will influence the type of baseline available to be used in any particular geographic area. A coastal State may employ different baseline types (normal,Footnote 10 straight,Footnote 11 archipelagic,Footnote 12 or a combination thereof)Footnote 13 if relevant criteria are met. The principal significance of the baseline in the law of the sea is that it is the starting point for determining the location and extent of a coastal State's maritime zones, such as the territorial seaFootnote 14 (which may be established with a breadth of up to 12 nautical miles from the baseline),Footnote 15 or the exclusive economic zone (with a breadth of up to 200 nautical miles from the baseline),Footnote 16 and States’ rights and responsibilities (for example, relating to customs enforcement, or environmental obligations) differ according to the maritime zone in which a particular activity occurs.
This article focuses on situations where maritime zones are established unilaterally by the coastal State. This occurs where such zones do not overlap with the entitlements of an adjacent or opposite coastal State (for example, where there is more than 400 nautical miles between opposite States, allowing each coastal State to claim an exclusive economic zone of 200 nautical miles’ breadth). In these circumstances, the legal framework described above is applicable and determinative regarding the location and extent of maritime zones. The following discussion briefly considers jurisprudence and scholarship relating to maritime boundaries between States. Although the concept of stability does arise in these contexts, so too do different legal considerations (such as equity), making it difficult to translate from these situations to that of unilateral maritime zones.
A. Jurisprudence and Scholarship on the Stability of Maritime Boundaries
A handful of international decisions have touched upon stability in the context of maritime delimitations. In Bangladesh v India, the Tribunal noted that ‘maritime delimitations, like land boundaries, must be stable and definitive to ensure a peaceful relationship between the States concerned in the long term’.Footnote 17 In a similar way, the ICJ has observed (in considering the exclusion of ‘boundary agreements’ from the rule permitting unilateral treaty termination where there is a fundamental change of circumstance) that ‘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 permanence’.Footnote 18 As explained by the Tribunal in Bangladesh v India, the stability of a maritime boundary between two States should be seen as an expression, in a maritime context, of the general principle in international law on the stability of land boundaries. A clear enunciation of that general principle may be found in the Temple of Preah Vihear, where the ICJ stated that ‘when two countries establish a frontier between them, one of the primary objects is to achieve stability and finality’.Footnote 19
Another context relates to the doctrine of uti possidetis, which provides that newly-independent States ‘inherit as their borders those administrative boundaries which were in place at the time of independence’,Footnote 20 providing a basis for the continuity of boundaries pre- and post- independence. It does so by preserving their location while at the same time transforming their legal status from internal boundaries to international ones. Uti possidetis also applies in the context of maritime delimitations, illustrated by the ICJ's inquiry into whether the waters of the Gulf of Fonseca were ‘divided or apportioned between the different administrative units which […] became the three coastal States of El Salvador, Honduras and Nicaragua’.Footnote 21 The Court in Nicaragua v Honduras also made clear that the application of the doctrine could provide for the continuity of borders encompassing the territorial sea (even though in this case, the evidence did not support Honduras’ claimed maritime boundary).Footnote 22
Treaty law also provides a source of stability for the maritime boundaries agreed between States. Lisztwan argues that this is because maritime boundaries fall within the exception in Article 62 of the Vienna Convention on the Law of Treaties Footnote 23 (applying the jurisprudence on land boundary delimitations, noted above), with the effect that ‘most maritime boundaries will not be affected by changes in coastal geography, providing substantial stability to areas of overlapping and contested maritime claims’.Footnote 24 Relatedly, Purcell contends that a principle of legal stability in the law of the sea should be recognised under the category of ‘relevant rules of international law applicable in the relations between the parties’,Footnote 25 and therefore relevant for the purposes of treaty interpretation. Purcell argues that for any particular maritime boundary treaty, the ‘principle of stability supports the conclusion that the ambulatory character of an international boundary should be clearly established by reference to the intentions evidenced by the particular boundary treaty, decision, or award’,Footnote 26 rather than presumed.
Common to these discussions is the recognition that a boundary in the ocean has a purpose analogous to a land boundary, in that both serve the goals of stability in the relations between neighbouring States. This is the case not only for borders delineating areas of sovereignty (such as territory or the territorial sea), but also for borders delineating areas of sovereign rights (such as an exclusive economic zone).Footnote 27
However, because the particular legal rules securing such stability arise in a bilateral context (such as a maritime delimitation dispute or treaty) it is difficult to translate them directly to the unilateral context, which is the focus of this article. Maritime boundary delimitation between States, whether through treaty or adjudication, is influenced by equitable principles.Footnote 28 While coastal geography remains important, the legal relationship between the ‘relevant coast’Footnote 29 and the associated maritime zone in a maritime boundary delimitation can also be influenced by a range of non-geographical factors including the availability of hydrocarbon resources, fisheries activities, and potentially navigational and security interests.Footnote 30 Where the delimitation is undertaken by a court or tribunal, an additional factor relevant to stability is the binding nature of third party decisions on parties to the dispute.Footnote 31 In relation to uti possidetis, the application of the doctrine presupposes not only a newly-independent State, but pre-existing administrative borders which are capable of being transformed into international borders. And the stabilising effect of treaty law, or application of a principle of stability to the interpretation of a boundary treaty, is available only where the coastal States have concluded such a treaty. There may be an argument that unilateral maritime zones should be treated as analogous with delimited maritime boundaries, on the basis that unilateral maritime zones also have a necessarily ‘international aspect’,Footnote 32 and so should have the same degree of legal stability. However, such normative arguments cannot assist the inquiry of this article into the extent to which legal stability is available under existing international law relating to unilateral maritime zones. That inquiry intersects with scholarship considering the nature of baselines under existing international law, which is discussed below.
B. The Problematic Logic Underpinning the ‘Ambulatory’ Theory of Baselines
Considering the close nexus between the land and the sea in the LOSC provisions on baselines, a rich scholarship has emerged assessing the possible legal implications for such baselines when there are changes to the coastline caused as a result of sea-level rise.Footnote 33 Do changes to the physical characteristics of the coastline entail changes to the corresponding baseline?
Scholarship on this question falls into three broad positions.Footnote 34 Some take a ‘fixed’ view of baselines, so that ‘once the normal baseline has been established and cartographically depicted on large scale charts, it remains in place until such time as it is redrafted, irrespective of whether or not the actual low-water line has physically moved’.Footnote 35 Another view, a variation of the first, is that baselines may be only temporarily fixed, and that there is an obligation ‘to update in the event of significant geographic change’.Footnote 36 While not couched in terms of stability, both these views clearly envisage a baseline remaining ‘in place’ or being temporarily ‘fixed’: here, legal stability may be achieved by establishing and charting the baseline, and such stability then continues to be available for the baseline notwithstanding changes to the low-water line along the coast.
But these views have not attracted broad support among scholars. The most widely-held view is the ‘ambulatory theory’ of baselines.Footnote 37 Under this view, ‘the normal baseline is constituted by the low-water line along the coast’,Footnote 38 and as a result, ‘[t]here is no doubt that changes in the shoreline, however and how quickly effected, result in changes in the baseline from which the territorial sea is measured’.Footnote 39 So as the shoreline ‘moves landward and seaward with accretion and erosion, so does the baseline. As the baseline ambulates, so does each of the maritime zones measured from it.’Footnote 40
The Baselines Committee of the International Law Association considered a range of expert views on the normal baseline and concluded that ‘[t]he preponderance of the scholarship in this area appears to support the view that charts are not determinative of the naturally ambulatory normal baseline’.Footnote 41 Those adhering to the ‘ambulatory theory’ of baselines point to two circumstances which, under that theory, provide for legal stability as a matter of exception. David Caron (who first articulated this argument, and whose work has been influential)Footnote 42 referred to the ability to temporarily maintain straight baselines under Article 7(2) of the LOSC where there are highly unstable deltaic coastal conditions causing the regression of the low-water line. Caron also noted the possibility that the outer limits of the continental shelf may have a degree of stability, since the LOSC provides that a coastal State may, after following the substantive and procedural requirements of Article 76, deposit information ‘permanently describing the outer limits of its continental shelf’.Footnote 43 Since no similar provisions expressly address the regression of the low-water line other than those in Article 7(2), and no similar provisions expressly ‘operate to freeze maritime boundaries’Footnote 44 other than potentially that of the continental shelf, Caron concluded that:
the outer boundary of the exclusive economic zone, the contiguous zone and the territorial sea are ambulatory in that they will move with the baselines from which they are measured.Footnote 45
In this way, the conclusion that baselines and outer limits have an ‘ambulatory character’ is underpinned by a ‘negative implication’Footnote 46 drawn from the language of Article 7(2) on deltaic baselines, and Article 76 on the continental shelf outer limit.
However, if we are interested in better understanding legal stability in connection with baselines, this logic is problematic for several reasons.Footnote 47 First, this argument assumes that the LOSC will signal its provision for legal stability through the use of words such as ‘remain’Footnote 48 and ‘permanent’Footnote 49 and ‘final’Footnote 50. But how does this account for the practice of States that is embedded within the meaning of other words, such as ‘officially-recognised charts’ in Article 5 on the normal baseline?Footnote 51 Second, the ‘negative implication’ makes much of one instance of legal silence in the LOSC (no general express provision for baseline stability), but does not account for the potential relevance of another legal silence (no positive duty to review or update maritime zones information). Third, considering that the LOSC jurisdictional framework permits coastal States to use a range of baseline types, and entitles coastal States to a number of maritime zones, could there be a potentially absurd result if only one type of straight baseline and one type of maritime zone outer limit has some degree of legal stability, but not any others? The effect of assuming that legal stability is exceptional to one type of baseline and one type of outer limit obscures the possibility that such stability may be more broadly available for baselines and maritime zones than the ‘ambulatory’ theory of baselines suggests.
This article now turns to exploring that possibility.
III. What do States say about legal stability in connection with maritime zones?
Some expert bodies have begun to show signs of an emerging recognition of the importance of the concept of ‘legal stability’ in connection with maritime zones. For example, the International Law Association endorsed the view of its Sea-Level Rise Committee that ‘on the grounds of legal certainty and stability, provided that the baselines and the outer limits of maritime zones of a coastal or an archipelagic State have been properly determined in accordance with the 1982 Law of the Sea Convention, these baselines and limits should not be required to be recalculated should sea level change affect the geographical reality of the coastline’.Footnote 52 Aurescu and Oral (Co-Chairs of the ILC Study Group on Sea-Level Rise) made the preliminary observation that ‘the ambulatory theory/method regarding baselines and the limits of maritime zones measured from them does not respond to the concerns expressed by Member States that are prompted by the effects of sea-level rise, especially as regards the rights of the coastal State in the various maritime zones, and the consequent need to preserve legal stability, security, certainty and predictability’.Footnote 53 But what does it mean to refer to ‘legal stability’ in connection with maritime zones? Though the term refers to the legal artefacts of maritime zones (and their constituent parts, such as the baseline and outer limit) it is not itself a term of art, nor drawn from legal instruments or jurisprudence: its origins lie in the discourse of States.
To begin to give substance to the meaning of ‘legal stability’ in this context, this Part examines selected State discourse during two historical periods. The first period (1973–1982, Section A) relates to the Third United Nations Conference on the Law of the Sea (UNCLOS III), which culminated in the adoption of the LOSC: this period gives insights into the goals of the drafters in designing the architecture of the LOSC, and in particular the zonal allocation of rights and responsibilities. The second period (2017–2021, Section B) covers the beginning of States’ formal discussion of sea-level rise and maritime zones in the international community (2017), up to the 76th session of the UN General Assembly (UNGA76, in 2021), at which States debated the ILC's work on the topic for the first time. States have affirmed their concern for the value of legal stability over both periods, though there is evidence that in response to the particular challenge of sea-level rise, States’ views suggest both increasing support for the concept, as well as a more substantial understanding of what such legal stability entails.
A. 1973–1982: Bringing Stability to Chaos
Delegates representing a range of geographic regions and maritime interests expressed the hope and intention that the work of UNCLOS III would promote stability in the oceans. The first president of UNCLOS III encapsulated this sentiment when stating that
a convention or conventions ensuring a generally acceptable, stable and durable law of the sea would be not only a monument to the patience, perseverance, diplomatic skill and spirit of fraternal cooperation of the participants and the States they represented, but would also honour the highest ideals of the Charter and other international legal instruments which sought to express the aspirations and yearnings of all peoples of the world.Footnote 54
Indeed, this need for stability had become pressing by the mid-twentieth century, a period described by the third president of UNCLOS III as one in which ‘the old legal order had collapsed and the world was faced with a plethora of conflicting claims for jurisdiction and resources by coastal States. Instead of order, we had chaos.’Footnote 55 At this time, the question of the breadth of the territorial sea remained unresolved (not having been agreed in discussions at the Hague Conference in the 1930s, the 1958 Convention on the Territorial Sea and Contiguous Zone, nor at UNCLOS II in 1960). Meanwhile many coastal States had asserted some form of maritime jurisdiction exceeding the traditionally-recognised breadth of the territorial sea of 3 nm: these included the United States’ 1946 Truman Proclamation claiming jurisdiction over its adjacent continental shelf, the 1952 Declaration of Santiago by Chile, Peru and Ecuador to sovereignty and jurisdiction over its ocean not less than 200 nm from its coast,Footnote 56 and claims by Indonesia and the Philippines to enclose the interconnecting waters of their outermost islands as internal waters.Footnote 57
Against this backdrop, States expressed the concern during the negotiations at UNCLOS III that an unfettered ability to determine national maritime zones would ‘create permanent instability and a proliferation of legal conflicts among States’.Footnote 58 Particularly salient noting the significant participation of newly-independent States in UNCLOS III, the path towards avoiding such instability would require balancing the full range of interests:
resolved in a spirit of accommodation, so that the necessary consensus could be reached. But consensus did not mean the majority bowing to an intransigent minority, or the bullying of a minority by an unthinking majority. All States would benefit if, by yielding a little, they could attain stable legal rights and benefits.Footnote 59
At the conclusion of UNCLOS III, Indonesia remarked that this approach to negotiations also contributed to the political legitimacy and durability of the resulting treaty, because it was
the result of long years of negotiation and represented compromises that balanced all the conflicting interests of different States. As such it offered the best guarantee for the stability and orderly development of the world's oceans and there was no viable alternative for promoting law and order in ocean affairs.Footnote 60
Stevenson and Oxman write that ‘the goal was a stable accommodation of coastal and maritime interests both within and between coastal States that would be respected by each state's class politique as a continuing restraint upon its jurisdictional choices’.Footnote 61 In this way, the stabilising purpose underlying the zonal allocation of jurisdiction in the LOSC was not only set against the mischief of a ‘plethora of conflicting claims for jurisdiction and resources’, but also intended to uphold a new balance of interests in the ocean that reflected the geopolitics of the time. States identified political and practical implications of the new regime, such as ‘the importance of navigation and overflight through straits for the global flow of trade and communications and for a stable and peaceful world order’,Footnote 62 and how common rules to govern exploitation of natural resources may promote equity and avoid conflict.Footnote 63 Indeed, States viewed the new legal order of the oceans as vital ‘for the promotion of the rule of law in international affairs, and hence the shaping of a peaceful world with a stable and equitable world order’.Footnote 64
The resulting ‘package deal’Footnote 65 of the LOSC was adopted in 1982 and presently has 168 Parties (including the European Union),Footnote 66 and its preamble sets out the aspirations of States to establish ‘a new legal order for the seas and oceans which will facilitate international communication, and will promote the peaceful uses of the seas and oceans, the equitable and efficient utilization of their resources, the conservation of their living resources, and the study, protection and preservation of the marine environment’.Footnote 67 This period demonstrates the concern of States for legal stability in connection with the overall system of maritime zones, at risk in the ‘chaos’ of unfettered and conflicting maritime claims, and brought to order in the agreement of the LOSC framework.
B. 2017–2021: The Affirmation of Legal Stability and Its Substantive Development
This section now considers the period almost 40 years after the conclusion of the LOSC, at which time States’ concerns for legal stability may be seen again in the context of discussions on sea-level rise. Key milestones in this period commence with the beginning of States’ engagement with the topic in 2017 (formally calling for the International Law Commission (ILC) to consider sea-level rise) up to UNGA76 at the end of 2021. The inclusion of the topic of sea-level rise in international law on the ILC's programme of work is significant not only because of the ILC's scholarly contribution to these substantive questions, but also because it has prompted the engagement of States. States have submitted information to the ILC (individually or also as part of a regional group, such as the Pacific Islands Forum or the Association of Small Island States), and have also participated in discussions on the topic in the UN General AssemblyFootnote 68 and the UN Open-ended Informal Consultative Process on Oceans and the Law of the Sea, which in July 2021 dealt with ‘Sea-level rise and its impacts’.Footnote 69 An analysis of the written and oral statements made by States in these settings reveals a range of views regarding legal stability in connection with sea-level rise and maritime zones. Some views clearly support sentiments expressed during the LOSC's development, and other views show signs of substantive development.
During this period, States continued to articulate a concern for legal stability in connection with the overall framework of the LOSC and the ‘legal order’ buttressed by it. States also affirmed the importance of ‘a common set of rules’ set out in the LOSC, applicable to all, and that the question of sea-level rise should be approached with a concomitant concern to ‘safeguard and strengthen the Convention system’.Footnote 70 While different views were expressed on the need for new laws to address this topic, States nevertheless identified features of the existing law that continued to be relevant: the balance of rights and obligations should be preserved,Footnote 71 noting not only the rights of coastal States to maritime zones, but also the rights of third States.Footnote 72 States should continue ‘to maximize the stability and clarity that the Convention brought to oceans governance and maritime jurisdiction’.Footnote 73 Otherwise, ‘[j]urisdictional uncertainty could cause enforcement issues and create potential for conflict in the region’Footnote 74 and prompt disputes.Footnote 75 Any approach to this issue should affirm ‘the centrality of the United Nations Convention on the Law of the Sea and strive to preserve its integrity and the stability provided by its rules’.Footnote 76 Caution should be exercised in relation to ‘any interpretation that would undermine the delicate balance of rights and obligations set out in the United Nations Convention on the Law of the Sea or its universal and unified character. It was important to proceed on the basis of legal stability, security, certainty and predictability in international law.’Footnote 77 These themes clearly reinforce many of the original objectives of the LOSC to establish a stable zonal allocation of rights and responsibilities in ocean space, outlined above in Section A.
During this period, States have also begun to refer more directly and concretely to stability in connection with maritime zones. One indicator of this is an express engagement with the term ‘legal stability’: of the 66 delegationsFootnote 78 which substantively addressed the topic of sea-level rise at UNGA76, 14Footnote 79 used the term ‘legal stability’ in connection with maritime zones, of which three expressly turned to the meaning of ‘legal stability’: Sierra Leone noted the ILC discussionFootnote 80 on the term's meaning ‘with interest’,Footnote 81 and ChileFootnote 82 and Papua New GuineaFootnote 83 agreed that the term referred to ‘the need to preserve the baselines and outer limits of maritime zones’.
Furthermore, States’ comments have begun to give substance to this idea, in particular by illuminating different dimensions of their concern for legal stability in connection with maritime zones. Some States draw attention to a spatial dimension of their concern, in the sense of connecting the goal of stability with certain practical steps taken by States to define their baselines. For example, Belize (on behalf of the Association of Small Island States) outlines how ‘[m]any small island and low-lying States had taken political and legislative measures to preserve their baselines and the existing extent of their maritime zones by adopting domestic laws, concluding maritime boundary agreements and depositing charts or coordinates along with declarations’.Footnote 84 Micronesia gives an example of this position, explaining how it had in 2019 ‘deposited with the Secretary-General lists of geographical coordinates of points, accompanied by illustrative maps, for the maritime zones of the Federated States of Micronesia’,Footnote 85 accompanied by its observations that ‘it understood that it was not obliged to keep under review the maritime zones reflected in the deposit; and that it intended to maintain those zones in line with that understanding, notwithstanding climate change-induced sea-level rise’.Footnote 86 The Solomon Islands explained it had also taken this approach, describing that ‘[i]n accordance with international law and regional practice, the Solomon Islands had deposited geographic coordinates for nearly all its maritime zones with the Secretary-General. Those zones were fixed and should not be altered, despite sea-level rise.’Footnote 87 Similarly, the Maldives expressed the view that ‘once a State deposited the appropriate charts and/or geographic coordinates with the Secretary-General, those entitlements were fixed and would not be altered by any subsequent physical changes to the State's geography as a result of sea-level rise’.Footnote 88
In these comments, States draw attention to the importance of particular domestic actions to implement their baselines and maritime zones in connection with the goal of stability: namely, the use of charts and/or geographic coordinates to define the relevant lines and areas in order to ‘fix’ their location on the surface of the earth. This is key to understanding the spatial dimension of legal stability: defining a baseline or outer limits by means of a chart and/or coordinates is part of what makes those lines capable of remaining in the same location, what gives the legal artefacts of the baseline and the maritime zone the capacity to occupy the same location and space on the surface of the earth. As Part IV will demonstrate, this practice is widely found in the domestic legislation of many States.
These statements also show that States see this spatial dimension interacting with a temporal one, in the sense that once the maritime zones information has been established by charts and/or coordinates, those States consider that baseline or maritime zones may remain in place over time. In support of this view, Belize, Micronesia, the Maldives and the Solomon Islands (and others) agree with Aurescu and Oral's preliminary observation that the LOSC does not contain any express obligation to update maritime zones information once established and published.Footnote 89 Fiji,Footnote 90 on behalf of the PIF, drew attention to the PIF Declaration, which relevantly states that ‘the Convention imposes no affirmative obligation to keep baselines and outer limits of maritime zones under review nor to update charts or lists of geographical coordinates once deposited’.Footnote 91 In very similar terms, Antigua and Barbuda pointed out that the leaders of the members of the Alliance of Small Island States had also in 2021 affirmed ‘that there is no obligation under the United Nations Convention on the Law of the Sea to keep baselines and outer limits of maritime zones under review nor to update charts or lists of geographical coordinates once deposited with the Secretary-General of the United Nations’.Footnote 92 The emerging discussion on maintaining baselines and maritime zones once established and publicised, continuing in their effect over time, draws attention to a temporal dimension of the notion of legal stability.
A handful of States also point out implications for stability of legal status under the LOSC: this issue arises because certain questions of legal status also have a close nexus to the land. For example, an island is ‘a naturally formed area of land, surrounded by water, which is above water at high tide’;Footnote 93 and only States which are constituted by archipelagos—meaning ‘a group of islands, including parts of islands, interconnecting waters and other natural features which are so closely interrelated that such islands, waters and other natural features form an intrinsic geographical, economic and political entity, or which historically have been regarded as such’—may have status as an ‘archipelagic State’.Footnote 94 Questions of status are key for maritime zones since not all maritime zones are available for all types of legal status: under Article 121 of the LOSC, an ‘island’ is entitled to the full suite of maritime zones, while ‘[r]ocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone or continental shelf’.Footnote 95 Similarly, ‘archipelagic waters’Footnote 96 are available only to archipelagic States. Considering the possibility that sea-level rise might impact the geographic features relevant to these kinds of legal status, Antigua and Barbuda took the view that ‘sea-level rise cannot lead to the requalification of islands as rocks’.Footnote 97 In a similar vein, Papua New Guinea expressed the concern that ‘potential loss, owing to sea-level rise, of small islands and other features that served as basepoints could affect existing maritime zone entitlements and could compromise the ability of an archipelagic State to maintain that status’,Footnote 98 noting also the relationship between maritime entitlement with statehood ‘[a]s only States could generate maritime zones, it was essential for island States to maintain statehood in order to preserve their maritime zones’.Footnote 99
Seen in this way, the views expressed by States in these discussions give meaning to the concept of ‘legal stability’ in connection with maritime zones by highlighting its different dimensions relating to space, time and status. A brief note of caution is required here, since this analysis of States’ representations takes into account the views of only those States which have publicly participated in the settings examined: for example, out of 168 LOSC PartiesFootnote 100 (noting also there are 14 non-Parties which are coastal States),Footnote 101 66 delegationsFootnote 102 made oral statements at UNGA76 and 13 States made submissions to the ILC.Footnote 103 Further, there is some variation in State practice revealed in States’ interventions: for example, while some States emphasise the absence of a duty to update, other States point to their practice of updating charts (for example, the United States and the Netherlands).Footnote 104 With this caution in mind, this analysis of States’ views nevertheless demonstrates that legal stability has retained its relevance from the conclusion of the LOSC up to now.
Across both time periods examined, States have shown that their concern for the stability for the LOSC zonal framework is similar to the role stability plays in the context of land boundaries: at this level, stability may be seen as an end-state secured by legal means (the LOSC framework), and pertains to stable relations between States achieved by means of the LOSC system a whole, including maritime zones. States’ interventions in the latter period also show some substantive development of the concept as it relates to baselines and maritime zones in particular: States have begun to translate the goal of stability into this context (referring to the preservation of baselines and maritime zones), and to identify different dimensions of stability in relation to space, time and status. In this more concrete sense, legal stability entails the preservation of spatially-defined rights.
And as the following Part will show (and some States, such as Belize, foreshadowed), what States do when implementing their baselines is closely connected to maximising such legal stability.
IV. What do States do when they implement their baselines (and do some methods achieve more or less stability)?
This Part offers evidence that States also pursue legal stability in the way they implement baseline provisions of the LOSC in their domestic frameworks. Taking the normal baseline as a focus, the study shows that States’ methods of implementation fall into four broad groupings. As is explained below, this reveals a more diverse implementation practice than previous studies have shown. Noting especially the prevalence of the use of coordinates, this also prompts an inquiry into the significance of practice not expressly envisaged by the language of Article 5 on the normal baseline, and a consideration of whether some implementation methods are capable of offering a greater degree of spatial stability than others.
A. Rationale and Method for a Case Study on the Normal Baseline
This article presents a case study focussed on the normal baseline because it is the dominant type of baseline:Footnote 105 Article 5 of the LOSC defines it as ‘the low-water line along the coast as marked on large-scale charts officially recognized by the coastal State’.Footnote 106
The case study has sought to be as comprehensive as possible in examining the legislation of all coastal States. Out of 193 UN Member States,Footnote 107 150 are coastal States (comprising 136 Parties to the LOSC and 14 non-Parties). In addition to these and for consistency with the approach taken by the UN Division of Ocean and Law of the Sea (UN DOALOS), this study also included the State of Palestine,Footnote 108 Niue and the Cook Islands,Footnote 109 bringing the overall sample size to 153 coastal States.
The study took a broad approach in characterising the relevant ‘legislation’ for the purposes of the survey,Footnote 110 including both primary and secondary legislation, as well as other instruments within the relevant national framework (for example, an Order, Decree or Proclamation).
The study examined the legislation of each coastal State to answer the following questions:
• Does the coastal State use the normal baseline?
• How does the legislation define the normal baseline?
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○ Does the legislation define the normal baseline by reference to the terms/concepts ‘low-water line’ and ‘charts’ (reflective of LOSC Art 5)?
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○ Does the legislation define the normal baseline by reference to other concepts (including those not expressly reflective of LOSC Art 5), such as coordinates?
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The case study builds upon two other studies collecting information on the normal baseline. The first was conducted by the ILA Baselines Committee, which undertook to ‘identify, categorize, and provide representative examples of a robust sample of relevant state practice through a survey of the practice of Committee members’ home States, among other States’. One hundred and twenty-four coastal States are referred to in the Report's footnotes (including both Parties and non-Parties to the LOSC).Footnote 111 However, the Committee was focussed on the use or non-use of charts in legislation,Footnote 112 and did not discuss the prevalence or significance of other methods. The second study is that presently occurring in the ILC, led by the Study Group on Sea-Level Rise. However, both the ILC as a wholeFootnote 113 and Aurescu and OralFootnote 114 have remarked that further evidence of State practice is needed, and in that context, the ILC has not yet made any conclusions on global legislative practice.
The findings of this study aim to contribute to this exercise, offering a comprehensive examination of coastal States’ legislation on the normal baseline, proposing a typology of definitions that includes all approaches observed in such legislation, and leaving scope for an inquiry about legal stability.
B. Findings on the Normal Baseline
1. Summary of overall findings
Out of 153 coastal States surveyed, 108 (71 per cent) coastal States use the normal baseline.Footnote 115 Noting that many coastal States use a combination of methods in the context of their overall baseline system (either implementing the normal baseline in different ways for different segments of the coast; and/or using a combination of normal, straight or archipelagic baselines), the survey identified 117 uses of normal baseline definition.
The study classified those 117 definitionsFootnote 116 of the normal baseline into four types of definition, where the national legislation specifies that the normal baseline is:
• ‘the low-water line (along the coast)’ (Type 1)
• located by reference to coordinates (Type 2)
• ‘the low-water line as marked on charts’ (Type 3)
• ‘determined in accordance with international law’ (Type 4).Footnote 117
The first of these—legislation which specifies that the normal baseline is the low-water line along the coast—is the most commonly used method, comprising approximately 41 per cent of methods observed. The next most prevalent method is legislation which specifies the location of the normal baseline by reference to coordinates (approximately 30 per cent), followed closely by legislation which specifies that the normal baseline is the low-water line as marked on charts (approximately 25 per cent). A handful of coastal States (approximately 4 per cent) specify that the normal baseline is determined in accordance with international law.
The following section discusses each of these methods in decreasing order of prevalence, offering examples to illustrate each type of definition.
2. Type 1: Normal baseline is the low-water line (along the coast)
The survey identifies 48 occurrences in which a coastal State defines the normal baseline as the low-water line along its coast; of these, 43 are in the legislation of coastal States Parties to the LOSC,Footnote 118 and five in that of non-Parties.Footnote 119 The survey classified a definition as Type 1 if it defines the normal baseline only by reference to the low-water line along the coast, and not also by reference to other concepts such as charts or coordinates.Footnote 120
A central feature of this type of definition is that the legislation identifies the normal baseline with the low-water line along the coast (whether or not the coast is expressly referred to). For example, the legislation of Honduras provides that the ‘normal baseline for measuring the breadth of the Honduran territorial sea and other maritime areas is the low-water line along the coast’;Footnote 121 similarly, the legislation of Guinea states that ‘baselines are comprised of the low-water mark and the straight baseline’,Footnote 122 and that of Slovenia states that ‘the baseline shall be the hydrographic zero line running along the coast’.Footnote 123 The study includes such variations in this category where the apparent meaning is that the normal baseline is in principle defined as a line along the coast, taking from the coast its direction and shape.
In this way, a Type 1 definition locates the normal baseline by pointing to a specific physical feature on the surface of the earth, which is the low-water line along the coast.Footnote 124 And importantly (and in contrast to Type 2 and Type 3 definitions, discussed below), in this type of definition, the legislation refers to the coast as the sole reference point for locating the normal baseline.
3. Type 2: Normal baseline is located by reference to coordinates
The second most prevalent group is the Type 2 definition, where the normal baseline is located by reference to coordinates. The survey identified 35 instances of these: 34 are in the legislation of LOSC partiesFootnote 125 and one in a non-Party.Footnote 126
The study revealed two ways in which coordinates are used in the context of the normal baseline. First, some coastal States use coordinates to link segments of a mixed baseline system, that is, linking the normal baseline together with other baseline types. A good example is the legislation of France concerning the continental mainland and Corsica, which provides that ‘the baselines from which the breadth of the territorial sea adjacent to the Mediterranean continental seaboard is measured, shall be defined by the following basepoints and lines’.Footnote 127
The Decree specifies that the baseline is to be located by reference to the listed geographic coordinates, as well as specifying the type of line that links those co-ordinates, which ‘may be a rhumb line (a straight baseline) or the low-water line’.Footnote 128
A similar approach is found in the legislation of Canada,Footnote 129 Costa Rica,Footnote 130 Denmark,Footnote 131 Democratic Republic of the Congo,Footnote 132 Estonia,Footnote 133 Indonesia,Footnote 134 Iceland,Footnote 135 Lithuania,Footnote 136 Mauritius,Footnote 137 Ukraine,Footnote 138 UruguayFootnote 139 and Peru.Footnote 140 Common to these examples is that coordinates are specified in the legislation with information that the points are to be linked by the low-water line along the coast, or similar wording (such as ‘the coastal line’Footnote 141 in Danish legislation).
A variation of this kind of approach can be seen in the legislation of a handful of coastal States which, instead of specifying that the normal baseline is the low-water line between particular coordinates, rather refer to a charted low-water line between specified points. The legislation of Brazil defines the normal baseline as ‘the low-water lines as indicated in the large-scale nautical charts published by the Directorate of Hydrography and Navigation of the Brazilian Navy’Footnote 142 and also stipulates that the ‘coordinates of the starting and final points, as well as those of the points defining the continental and insular SBL [straight baselines] that constitute the Baseline of Brazil are contained in the Annex’.Footnote 143 This approach is also taken in Angola,Footnote 144 Argentina,Footnote 145 Bangladesh,Footnote 146 and India.Footnote 147
The second way in which coordinates are used to locate the normal baseline is where coordinates are used for the entirety of the normal baseline around a whole feature or coastal front. For example, Samoa declared that its ‘Territorial Seas Baseline shall comprise of a series of successive geographical coordinates located on the outermost reef edge points around and classified as normal baseline’Footnote 148 and Palau lists coordinates for the normal baseline along fringing reefs at North Coast and East Coast.Footnote 149 The Cook Islands,Footnote 150 Republic of the Marshall Islands,Footnote 151 Fiji,Footnote 152 Federated States of Micronesia,Footnote 153 Kiribati,Footnote 154 Nauru,Footnote 155 Vanuatu,Footnote 156 Niue,Footnote 157 Seychelles,Footnote 158 PalestineFootnote 159 and TuvaluFootnote 160 all take a similar approach.
Coordinates express location by referring to a geographic grid created by ‘two sets of imaginary lines around our earth’, allowing the statement of ‘the absolute location of any point on the earth by calculating the degrees of latitude north or south of the equator and the degrees of longitude east and west of the prime meridian’.Footnote 161 Where a Type 2 definition uses coordinates as turning points in a mixed baseline system, normal baseline segments are anchored to an ‘absolute location’ by the same coordinates that are the endpoints of neighbouring straight or archipelagic baseline segments. Notably, these anchored segments of normal baseline rely on the physical coast or reef, or chart, for the location and shape of the line between the coordinates, a characteristic which a Type 2 definition has in common with Type 1 and Type 3. Where a Type 2 definition uses coordinates for the entirety of a normal baseline around whole features, that whole baseline may be seen to have an ‘absolute location’ too, in that it may be located solely by reference to coordinates (even if the legislation refers to a coast or reef, or provides an illustrative chart).
4. Type 3: Normal baseline is the low-water line as marked on official charts
The survey identified 29 occurrences in which a coastal State defines the normal baseline as that marked on officially recognized charts. Of these, 28 examples are in the legislation of coastal States Parties to the LOSC,Footnote 162 and one in that of a non-Party.Footnote 163
Many examples of legislation in this category employ language which closely mirrors all the elements of Article 5 of the LOSC on the normal baseline. Some, like that of the Republic of Korea, closely replicate that wording, stating that ‘the normal baseline for measuring the breadth of the territorial sea is the low-water line along the coast as marked on large-scale charts officially recognized by the Republic of Korea’.Footnote 164 Some legislation refers to charts in the context of defining or specifying the term ‘low-water line’. For example, after stating that the territorial sea shall be measured from the low-water line along the coast, the legislation of the Netherlands states that ‘the low-water line shall be defined as the line indicating the depth of 0 metres on the large-scale Dutch sea charts issued upon the instructions of the Minister of Defence’.Footnote 165 Similarly, Timor-Leste legislation states that ‘‘‘Low-tide line’’ means the low-tide line of the seashores of the territory of Timor-Leste, as shown in official larger-scale maps officially recognized by the Government of Timor-Leste’,Footnote 166 and that the normal baseline shall be ‘the low-tide line along the coast’.Footnote 167
Understanding the purpose of a chart sheds light on how a Type 3 definition works in practice. In the context of the LOSC, which refers to charts in numerous provisions in addition to Article 5 on the normal baseline, a chart is understood to mean a nautical chart,Footnote 168 which is a ‘map specially designed to meet the needs of marine navigation’.Footnote 169 It is apparent that national legislation also uses the term ‘chart’ in this way. Given the purpose of charts, where terrestrial maps focus on accurately depicting features of the land, a chart will focus only on those land features significant for navigation (whether for positioning, or presenting a potential hazard).Footnote 170 According to the International Hydrographic Organization, a ‘chart’ is
specifically designed to meet the requirements of marine navigation, showing among other things depths, nature of the seabed, elevations, configuration and characteristics of the coast, dangers, and aids to navigation. Nautical charts provide a graphical representation of relevant information to mariners for executing safe navigation.Footnote 171
And today, a chart is not confined to an analogue (paper) form (with historical antecedents including the Portolan charts of the fourteenth century).Footnote 172 Coastal States increasingly use electronic charts (either a raster chart or a vector electronic navigational chart),Footnote 173 and there are discussions in the international charting community about the future of the paper chart.Footnote 174 While a raster chart is a simply a scanned, passive image of a paper chart, a fully digitised electronic navigational chart (ENC) contains vector data and is essentially a ‘digital database of all the objects (points, lines, areas, etc) represented on a chart’.Footnote 175 This means that a low-water line on an ENC will be a line made up of points, each of which correspond to certain geographic coordinates.Footnote 176 In this way, if a coastal State uses an ENC for the purposes of its normal baseline, the charted low-water line very much resembles a line that is specified by reference to coordinates; it is just that the ENC presents a visual representation of the information, in a way that a bare list of coordinates does not. Many countries now use or produce ENCs,Footnote 177 including those identified here as using a Type 2 definition of the baseline (eg Canada).Footnote 178
For these reasons, legislation adopting a Type 3 definition of the normal baseline relies on a ‘graphical representation’ of relevant information about the coast, or in the case of an ENC, embedded digital information as well.
5. Type 4: Normal baseline is determined in accordance with international law
The survey identifies five occurrences in which a coastal State defines the normal baseline as determined under, or in accordance with, international law. Of these, four examples are in the legislation of LOSC Parties,Footnote 179 and one in that of a non-Party.Footnote 180
The United Kingdom's legislation states that ‘the baselines from which the breadth of the territorial sea adjacent to the United Kingdom, the Channel Islands and the Isle of Man shall be established in accordance with the relevant provisions of the United Nations Convention on the Law of the Sea’.Footnote 181 The Explanatory Memorandum makes clear that this includes the use of the normal baseline insofar as ‘[g]enerally the baseline will follow the low-water line, except that a straight line can be drawn across bays’.Footnote 182 Similarly, ‘the territorial sea of the United States henceforth extends to 12 nautical miles from the baselines of the United States determined in accordance with international law’Footnote 183 and for the external territories of Australia, maritime zones are measured from ‘baselines established under international law’.Footnote 184 In practical terms, the USAFootnote 185 and Australia's external territories also use the normal baseline.Footnote 186 Since this definition type does not specify any particular method for locating the normal baseline, the degree of spatial stability relevant to any of these coastal States’ segments of normal baseline specified in this way will depend on practical or policy factors outside the legislation itself (for example, if the coastal State in practice uses coordinates or an official chart for the purposes of its baseline). The influence of such extra-legal factors has not been explored here, since this study has focused on legislation alone.
C. Analysis of Findings and Implications for the Legal Stability of Maritime Zones
This snapshot of what States do when they implement the normal baseline gives us three key insights pertinent to legal stability and maritime zones. First, the results show that there is a greater diversity in the types of definition of the normal baseline than appreciated in previous scholarship. In particular, not only is there a distinction between the use and non-use of charts (as identified in the ILA Baseline Committee's 2012 study), but the study has identified a new category (one that relies on coordinates) and which is the second-most prevalent definition. Secondly, while UN DOALOS recordsFootnote 187 show that the declaration of some States’ maritime zones has at times met with protest, none of these protests relate to what type of definition a coastal State has used for the normal baseline; this is the case even for those using a Type 2 definition, which does not strictly follow the language of Article 5 in the way that a Type 3 definition does. This tends to suggest a general acceptance of a diversity of methods to implement the normal baseline in domestic frameworks, and specifically an acceptance of a broadening of acceptable methods to include an increasing reliance on coordinates.Footnote 188
Thirdly, the definition types differ in the way they locate the normal baseline on the surface of the earth. States have begun to articulate a spatial dimension of stability:Footnote 189 some States have drawn the connection between a legal approach in implementation (a definition type that defines a baseline or outer limits by means of a chart and/or coordinates) and resulting stability (that definition type is what makes those lines capable of remaining in the same location). Accordingly, the legal stability of the normal baseline (at least, its spatial dimension) is influenced by the type of definition used in its implementation. If Types 2 and 3 are grouped together on the basis that both charts and coordinates offer some stabilising effect, this represents 64 out of 117 uses of the normal baseline (approximately 55 per cent).
V. Conclusion
This article contends that the PIF Declaration's claim for the preservation of baselines and maritime zones in the face of climate-change induced sea-level rise is not radical because it is both an expression of the long-standing value placed on legal stability in the LOSC system by States, and consistent with the practice of many States which have secured legal stability for their normal baselines within their domestic frameworks, to apparent general acceptance. For these reasons, we should take seriously the interpretative claim in the PIF Declaration that ‘maintaining maritime zones established with the Convention, and rights and entitlements that flow from them, notwithstanding climate change-related sea-level rise, is supported by both the Convention and the legal principles underpinning it’.Footnote 190
Three consequences flow from this. First, it invites us to revisit the dominance of the widely-held view of many writers that baselines are ambulatory. The evidence of what States say and do about legal stability calls into question whether the ‘ambulatory theory’ of baselines fully accounts for the diversity of State practice. Further, given the emphasis placed on legal stability in the establishment of the LOSC's jurisdictional framework, it seems an absurd result if only one type of straight baseline and one type of maritime zone outer limit have some degree of legal stability, but not any others. Indeed, States’ discussion of stability during the period 2017–2021 is framed in broad terms, not generally differentiating between the various baseline types or outer limits for particular zones. Only the archipelagic baseline is given particular mention (not the deltaic baseline under Article 7(2), as one might expect): the Solomon Islands and Papua New Guinea point to the stability of archipelagic baselines, expressing their view that such baselines (as well as each country's delimited maritime boundaries) are not subject to change.Footnote 191 These statements support the idea that there is a more broadly available legal stability that States call upon to be ‘maximised’ or ‘preserved’. Such broad claims are at odds with the notion that legal stability is available only in limited circumstances, as would be the case under an ‘ambulatory theory’.
Secondly, what States say and do about legal stability matters directly to explicit elements of an exercise of treaty interpretation of the LOSC: what States say might provide evidence of the object and purpose of the LOSC,Footnote 192 or evidence of the agreement of LOSC parties regarding its interpretation;Footnote 193 what States do very likely amounts to subsequent practice in application of the LOSC baseline rules.Footnote 194 And while custom is not mentioned in the PIF Declaration, there is room left for its parallel development. The ILC has signalled that in its future work on the issue, it will consider all relevant sources of law—in both treaty and custom. When applying the analytical frameworks for treaty interpretation and the identification of custom, the ILC should do so with its eyes open to the potential legal significance of what States say and do about legal stability and maritime zones.
Thirdly, addressing a conceptual blind spot to look squarely at legal stability for maritime zones means that it is also necessary to grapple with the question of how much legal stability can or should exist. As many have pointed out, UNCLOS III did not canvas sea-level rise, climate change more broadly, nor any of their possible legal impacts on the LOSC jurisdictional framework.Footnote 195 This is unsurprising, since it was only after the conclusion of the LOSC in 1982 that the international community began seriously to engage with such matters.Footnote 196 From the early twenty-first century, scholars began to articulate the emergence of the Anthropocene,Footnote 197 a new geological epoch characterised by human impacts on the earthFootnote 198 which challenges ‘the assumption, based on our experience so far, of constantly stable circumstances of the late Holocene. Many aspects of international law are based on such understanding of the stability of the Earth conditions.’Footnote 199 Our focus needs to shift to considering how much legal stability is available for baselines and maritime zones, now that States better appreciate that there is increasing geographic instability.
Fully addressing the question of how much entails taking a cue from what States say, to look at the different dimensions of legal stability. To understand its temporal dimension more fully, it is necessary to examine the increasing prominence placed on the LOSC's silence regarding a duty to update baselines and outer limits once they have been notified to the international community through an act of deposit. Considering the stability of status might also require considering whether the principle of continuity of statehoodFootnote 200 may have any relevance in the context of questions of status under the law of the sea. This article has demonstrated that the capacity of the existing law to accommodate a measure of spatial stability is well illustrated by how many States have implemented their baselines in ways that have a stabilising effect.
Turning our focus to look squarely at legal stability means that evidence of its expression in States’ actions and pronouncements can now be brought to bear to better understand the existing international law in circumstances of sea-level rise.
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