Canute’s Kingdoms: Can small island states legislate against their own disappearance?

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It was recently drawn to my attention that Tuvalu and Kiribati have in recent years passed legislation, following a relatively common scheme, that removes reference to the low tide line as the baseline for measuring maritime zones and replaces it with a system of fixed geographic coordinates. (The Marshall Islands has taken a somewhat similar approach.) On its face, this may constitute a claim that their maritime baselines are permanently fixed. That is, they will not retreat or be redrawn with rising sea levels.

This might seem a small matter in the range of legal issues implicated by climate change – it is not.

As every public international lawyer probably recalls, at least after the South China Sea arbitration, an island (within the meaning of article 121 of the UN Convention on the Law of the Sea) generates a full suite of maritime zones but must be more than a mere rock incapable of sustaining human habitation or a maritime feature which is only above water at low tide. Imagine your national territory is composed of a series of islands, some of them quite small but generating extensive maritime zones. Long before you risk becoming completely “de-territorialised” by rising sea levels you might lose much of your national livelihood if islands previously generating exclusive economic zones become mere low tide elevations.

So the question becomes, can a state freeze the baselines from which its maritime zones are projected? (The question is sometimes posed as whether a state can fix its outer maritime boundaries, but as these are projected from baselines the better question is the former.) There are several exceptional legal cases that I will return to below, but I would like to start by outlining the skeleton a legal strategy for small island states wishing to fix or freeze their “normal baselines” in international law.

Freezing normal baselines

The first difficulty a state wishing to freeze it baselines will encounter is the fact that “normal baselines” under Article 5 of the UN Law of the Sea Convention are generally considered to be ambulatory. (See the survey of academic opinion in, for example, the International Law Association’s report on the issue from its 2012 Sophia conference.) That is, they change with the changing configurations of the coast. This is hardly surprising, as they are defined as conforming to the low water line which will change as the physical coastline does. The principle from the North Sea Continental Shelf cases that ‘the land dominates the ‘sea also mitigates in favour of ambulatory baselines.

If this is the prevailing interpretation of the Convention how might the law be changed? Several options have been canvassed in the literature. (See in particular the excellent book chapter by Rosemary Rayfuse here or here.) The international community could adopt a subsequent treaty dealing with this specific issue, as has happened in the case of migratory fish stocks. The UNCLOS Assembly of State Parties could adopt an interpretive resolution as it has done regarding the rules related to the Commission on the Limits of the Continental Shelf – although it should be noted that such resolutions thus far have only been on procedural matters. It is generally accepted that the cumbersome amendment procedures of the Convention itself are on likely to be used successfully.

The text of Article 5 refers to the “low water line … as marked on [official] large scale charts”. Thus a minority of scholars have suggested that baselines can be “fixed” by means of such charts rather than changing with the configuration of the coast or sea-levels. To the extent that such alternative approaches may be available to interpreting Article 5, the best route forward may be to establish subsequent interpretative practice or a subsequent customary norm. (I will set to one side the controversy about whether a subsequent custom could effectively amend a treaty and simply note that if there was widespread acceptance of that result in this particular case that would likely be sufficient.)

How might such an interpretive practice or new rule be achieved? Well, it would probably begin with a number of states passing legislation asserting the rule, as has happened here on a limited scale. Specially affected states could also gather together and make a political declaration on the topic. One could then attempt to cement opinio juris (either as to the correct interpretation of the convention or a new role of custom, or both) through a General Assembly resolution. Sufficient recognition that baselines can be frozen could thus be built up, either as a general “interpretative” rule on baselines or as one favouring States faced with an existential risk of de-territorialisation.

I note in passing that the issue of climate change and sea rise obviously affects every state with a coastline. I still think, however, there is a plausible argument that Island states at a risk of medium or long-term de-territorialisation are in a distinct class. That is, these States are specially affected by the risk of losing a more significant proportion of their maritime entitlements and having that happen more quickly than, for example, will occur as regards major continental coastal states.

What strategy is being pursued in practice?

What is interesting is that there does not seem to be any push at the political level at the United Nations in such a direction. Instead, the impact of sea level on international law remains widely viewed as a complex and politically sensitive package of issues that affects numerous areas of law including human rights, migration and refugee law. This is, of course, true. While placing the full range of sea level rise and international law issues on the International Law Commission’s long-term program of work in 2018 was a wise step, it is not one which is necessarily geared to the urgent resolution of increasingly pressing problems. This seems to me a reasonably narrow technical issue calling for norm entrepreneurship by those states most affected.

Some exceptional legal cases

It is worth noting that the literature also identifies some areas we are less radical but partial legal solutions may be available. Certainly, it is self-evident that archipelagic baselines are in a different category from normal baselines. There is a textually plausible (if not necessarily compelling) reading of the relevant provision of the convention, Article 47, which suggests that once declared, mapped and deposited with the UN Secretary General archipelagic baselined might be considered final. Further, while not strictly a question of baselines, where states with opposing coastlines have concluded a maritime boundary it is open to argument that one should apply the usual principle that boundary delimitation treaties create objective facts to be recognised by the rest of the international community. It is also noticeable that under the Vienna Convention on the Law of Treaties that the fundamental change of circumstances principle (rebus sic substantibus) does not apply to boundary treaties (Article 62(2)(a)).

Finally, a state which declares the outer limit of its continental shelf beyond 200 nautical miles in accordance with the recommendations of the Commissions on the Limits of the Continental Shelf has a continental shelf boundary which is said to be ‘final and binding’ (Article 76(8)). This provision is usually interpreted as being opposable to all other parties to the Convention.  One could thus have the curious situation of a State which has lost the baselines from which it once drew an exclusive economic zone but which retains a legal right to a proclaimed continental shelf. (Although one might set against this to governing principle that the continental shelf is the ‘natural prolongation’ of a State’s land territory, and thus argue that if that land has disappeared a State should no longer have a claim to a shelf.)

Interesting as all of these possibilities or anomalies within the existing law may be, they offer partial solutions at best to small island States which are not archipelagos.


The national legislation noted above may point an intriguing path towards new rule creation. The underlying legal issue is pressing. It seems to me that there is a compelling argument in favour of allowing those islands states most affected by rising sea levels to freeze their baselines, and there are some reasonably obvious paths towards that end which could be pursued. (Heller, in particular, has written recently on the extent to which the global south could more successfully deploy the specially affected state doctrine in the formation of new customary rules.)

There are some traditional concerns in the Law of the Sea which could be set against my tentative argument. The first is that it is not obvious that the Convention contemplated a ratchet effect to jurisdictional claims. That is, that states could never lose something once claimed but might retain the ability to make new claims should new islands, rocks or atolls emerge. In general, scholarship and major maritime states have resisted any sign of trends towards creeping jurisdiction and this might be thought to fall within that rubric. The second is that one of the compromises in the Convention is that between the interest of coastal states in the broader international community. Thus, every new jurisdictional claim over the sea or seabed is potentially subtraction from the freedom of the high seas or “the Area”, being that portion of the deep seabed beyond national jurisdiction treated as the common heritage of mankind and administered by the International Seabed Authority. These points are not trivial, but weighed against the existential issues for a class of predominantly small and far from wealthy States they do not seem to me to be compelling.

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Benoit Mayer says

February 21, 2019

Thanks for this very interesting analysis. I would add that there is also a question of causal responsibility, at least under the principle of common but differentiated responsibilities and respective capabilities, or even under the law of State responsibility for internationally wrongful acts. Small island States contribute very little to global greenhouse gas emissions (even on a per capita basis), but they suffer disproportionately from its impacts. Such considerations should weight, I suppose, when balancing the sovereign rights of these States with the freedom of the high seas and the common heritage of mankind. The international community is failing to prevent dangerous interference with the climate system and to preserve the marine environment; it should not be allowed to take advantage of its own wrongs by reclaiming sea areas from those States most affected as a result of climate change and sea-level rise.