Islands Held in Trust

On 1 September 2026, Vanuatu asked the International Court of Justice to settle a dispute with France “concerning Vanuatu’s sovereignty over Umaenupne (Matthew) and Umaeneg/Leka (Hunter) Islands” and to draw a single maritime boundary between Vanuatu and France “(with respect to New Caledonia)”. Neither State accepts compulsory jurisdiction, so Vanuatu relied on Article 38(5) of the Rules: the application is sent to France, but nothing happens unless France consents. Vanuatu, which led the push for the General Assembly’s request behind the 2025 climate change opinion, is once again testing what the Court can do for a small State.

It is tempting to treat France’s answer as a matter of diplomatic preference. In this post, I argue that it is not.

France as Trustee, Not Owner

The parenthesis in Vanuatu’s application carries the legal weight of the case. France claims the islands not for itself but for New Caledonia, a non-self-governing territory that has a legal status “separate and distinct” from France’s own. New Caledonia is on the UN list of non-self-governing territories, to which the General Assembly returned it in 1986. Under Article 73 of the Charter, France accepts that “the interests of the inhabitants of these territories are paramount” and takes on their well-being “as a sacred trust”. The Friendly Relations Declaration adds that such a territory has “a status separate and distinct from the territory of the State administering it” (p. 124) until its people have exercised self-determination. Three referendums on independence, held in 2018, 2020 and 2021 under the Nouméa Accord, did not settle whether New Caledonia’s people have exercised their right to self-determination. The last one was boycotted by the independence movement, and the settlement meant to follow it remains contested.

In the Chagos Advisory Opinion (hereafter Chagos), the Court drew the consequence of the right to self-determination for the territory itself, holding that the territory’s integrity is protected as a corollary of that right. The peoples of non-self-governing territories exercise self-determination in relation to their territory as a whole, whose integrity the administering Power must respect. Any detachment “by the administering Power” that does not rest on the freely expressed and genuine will of the people concerned violates that right (para. 160). Read in light of Chagos, New Caledonia’s separate status makes France a trustee of its own claim.

This trustee role does not deny that France is, for now, the sovereign. The Advisory Opinion instead qualifies what that sovereignty permits. If Matthew and Hunter are New Caledonian, as France maintains, France holds them for New Caledonia’s people. That people does not speak with one voice. In 2009, a Kanak and Socialist National Liberation Front (FLNKS) leader, Victor Tutugoro, signed a document with Vanuatu’s prime minister stating that the islands belonged to Vanuatu. France’s foreign minister rebuked the move, saying it was difficult for New Caledonia to act as if it were independent when it was not. The pro-independence movement restated its position in 2019, while three of New Caledonia’s four members of the French Parliament invoked the 2018 referendum against any loss of territory. France thus defends, in the name of a people, a claim that the territory’s main pro-independence movement disowns. And the stakes are not two uninhabited volcanic islands but the maritime zone attached to them, which is bigger than New Zealand’s land area and whose resources go to the heart of the inhabitants’ “paramount” interests. Whatever one makes of this, it is not the position of an owner free to deal with its property.

The Integrity Principle Cuts Both Ways

Vanuatu can invoke the same principle of territorial integrity (Chagos, paras. 153 and 160). Before independence in 1980, Vanuatu was the New Hebrides, itself a non-self-governing territory administered by the United Kingdom and France as a condominium. The historical record is thinner than either side admits. Recent archival work finds no evidence of the French annexation of 1929 or the 1976 transfer that the literature often cites. What the archives do show is that in 1965 Britain and France, the two condominium Powers, agreed between themselves that the islands belonged to New Caledonia rather than the New Hebrides, apparently to defeat a private claim to Matthew Island before the Joint Court of the New Hebrides.

The date is striking. It is the year of the Chagos detachment, and the period for which the Court held the right to the territorial integrity of a non-self-governing territory to be already customary (para. 160). If the islands belonged to the New Hebrides before that agreement, the agreement was a detachment from one non-self-governing territory by its administering Powers, one of which also administered the receiving territory. That is the conduct Chagos condemns (paras. 172–174). If the islands never belonged to the New Hebrides, the agreement merely recorded the position, and France’s case stands.

Either way, neither government can settle the point by assertion. Applying the integrity principle first requires a finding on which colonial unit the islands belonged to before 1965, and on what weight to give the acts of administering Powers that were, on both sides, acting in trust. Title, critical date, colonial effectivités: this is the Court’s daily bread. The critical date also disciplines the evidence. Later French conduct, such as the January 2019 naval visit that Vanuatu formally protested, will count for little: the Court does not take into account acts after a dispute has crystallised unless they are a normal continuation of earlier acts and are not meant to improve a party’s legal position (Pulau Ligitan and Pulau Sipadan, para. 135).

Why Chagos Favours Adjudication over Bargaining

Consider the alternatives. The two governments opened formal talks in late 2025 and by mid-2026 had reached a deadlock. A negotiated settlement would mean trade-offs: France drops part of its claim in exchange for fishing access or a shared zone. But on France’s own case, any such concession is a disposal by the administering Power of part of New Caledonia’s territory. Under Chagos, that requires the freely expressed and genuine will of the territory’s people, which on this issue is split along the very line that divides New Caledonian politics.

A judgment would work differently. Paragraph 160 of Chagos targets detachment “by the administering Power”. A court that declares which State holds title is not an administering Power detaching anything; it states what the territory has always comprised. If the Court finds for Vanuatu, nothing has been taken from New Caledonia’s people, because the integrity principle protects a territory’s lawful extent, not its administrator’s claims. Adjudication lets France meet its trust obligations without making a choice it may lack the authority over. France also knows the route. It has twice accepted an Article 38(5) invitation: in 2003, the first acceptance since the provision was adopted in 1978, and again in 2006.

The strongest objection to the route of adjudication is that nothing obliges France to consent. As lex lata, that is right. Consent remains the basis of jurisdiction, and in East Timor the Court made clear that the erga omnes character of the right to self-determination does not displace the rule of consent to jurisdiction (para. 29). My claim is narrower: refusal is not neutral. Declining both adjudication and compromise through negotiation preserves an arrangement that, on Vanuatu’s account, came from an unlawful transfer between two non-self-governing territories, and it does so in the name of a people that never authorised it. An indefinite stand-off over the territory’s maritime resources hardly treats the inhabitants’ interests as paramount.

A second objection is that this stretches the Chagos Advisory Opinion too far. Administering Powers conclude boundary treaties for their territories all the time; France agreed to a maritime boundary with Fiji for New Caledonia in 1983, and no one calls that unlawful. But delimiting sea areas between undisputed coasts is not the same as giving up a claim to islands. Where an administering Power has done the latter, the matter has not stayed closed. In the 1980 Treaty of Tokehega, New Zealand, as Tokelau’s administering Power, agreed to a boundary that leaves Swains Island (Olohega), long regarded as Tokelau’s fourth atoll, on the American Samoan side. The island resurfaced in Tokelau’s self-determination debates of 2006 and 2007. Such bargains may settle the dispute between States; they do not settle the question of legitimacy.

Giving the Absent Party a Voice

The harder problem is procedural. Only States may be parties before the Court (Article 34(1) of the Statute), and only States may intervene (Articles 62 and 63 of the Statute). The Monetary Gold principle protects absent States, and recent debate on the Sapodilla Cayes case shows how much care the Court takes of them. Absent peoples get no such care: nothing in the case law would stop the Court from fixing New Caledonia’s territory without hearing anyone from New Caledonia. Advisory proceedings are more porous: the African Union took part in Chagos through a written statement and comments. Contentious proceedings have no equivalent door.

Within the existing law, three steps are available. France could make its consent conditional on consulting New Caledonia’s Congress and customary Senate. It could include New Caledonian representatives, the FLNKS among them, in its delegation; States can carry a people’s voice into the Great Hall, as Mauritius did in 2018 when a Chagossian, Liseby Elysé, addressed the Court by pre-recorded video as part of its delegation. And the Court could use Article 34(2) of the Statute to request information from the Pacific Islands Forum, which in 2016 admitted New Caledonia as a full member, the first time territories on the UN decolonisation list joined it.

De lege ferenda, the Rules should allow written observations from the representative institutions of a non-self-governing territory whose territory is at issue. Seventeen territories remain on the list, and the question Vanuatu’s application raises (that is, whose claim is the administering Power pressing?) sits beneath other disputes involving them, from the Falklands/Malvinas to Gibraltar. As long as their peoples cannot be heard, the right to self-determination, owed erga omnes, will keep being litigated and bargained over by trustees alone. Vanuatu’s application gives France, and the Court, a chance to show that a trust can be administered in the open.