Is the Prohibition of Forcible Annexations of Territory a Jus Cogens Norm?

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International law prohibits states from forcibly acquiring the territory of other states. But does this prohibition of the annexation of territory have the status of a peremptory or jus cogens norm? The question is unsettled. In the recent set of submissions to the International Court of Justice in the advisory opinion proceeding on the policies and practices of Israel in the Occupied Palestinian Territories, several states argue that it is a jus cogens norm, although they generally provide little support for that claim. The International Law Commission’s 2022 Draft Conclusions on Identification of Legal Consequences of Peremptory Norms of General International Law (jus cogens) does not list it as a jus cogens norm. To be sure, the ILC’s list does not purport to be exhaustive, and it does include the prohibition of aggression and the right of self-determination, both of which are related to the prohibition of annexations. In addition, the ILC separately cites “attempted annexations” as conduct that violates the right of self-determination. But it still does not demarcate the prohibition of annexations as a distinct jus cogens norm.

We argue in a forthcoming paper, The Prohibition of Annexations and the Foundations of Modern International Law, that the prohibition of annexations should have jus cogens status and that the ambiguity on this question reflects the confusion that surrounds it. This prohibition is often described as if it is fully subsumed within other international legal norms, including the prohibitions of the use of force and aggression and the right to self-determination. But as we explain in our paper, the prohibition of annexations has distinct significance. Historically, it has been central to three core projects in international law: (1) the entrenchment of state authority in defined territorial units, (2) the regulation of the use of force across (settled) territorial borders, and (3) the self-determination of peoples within such borders.

It also does things in law that none of the other norms with which it is associated do, whether on their own or together. For example, unlike the prohibition of the use of force, the prohibition of annexations (like the doctrine of conquest) specifically regulates sovereign title to territory. Regulating the acquisition of title to territory is distinct from regulating the use of force. In addition, the prohibition of annexations mediates tensions among the above three projects—for example, by clarifying that the self-determination of non-state groups generally “cannot be used to further larger territorial claims in defiance of internationally accepted boundaries of sovereign states.” In short, subsuming this prohibition into the other norms with which it is associated is both historically inaccurate and conceptually confused. It also tends to obscure the significance of territory in international law and the importance—to all three projects—of preventing coercive territorial changes.

The Prohibition of Annexations and the Advisory Proceedings on the OPT

Written submissions to the ICJ in the pending case on the OPT frequently describe Israel’s occupation of the West Bank and East Jerusalem as violating several peremptory norms, including the right of the Palestinian people to self-determination, as well as the prohibitions of the use force, racial discrimination, and apartheid. See, for example, Jordan’s written statement and Qatar’s helpful appendices to its written statement (summarizing the submissions of many other states). 

No mention of jus cogens norms is made in the written submissions from China, Russia, Switzerland. Neither does it appear in the written submissions of the United Kingdom, the United States or Fiji, all three of which urged the Court not to issue an advisory opinion in this case. Some states merely emphasize the importance of the prohibition—or invoke it to condemn Israel’s apparent annexation (or forcible acquisition) of Palestinian territory—without specifically labeling it a peremptory norm. France’s written statement, for example, cites the Friendly Relations Declaration and notes that “one of the cardinal principles of international law is that this kind of annexation is prohibited.” But France does not address its status as a peremptory norm.

Chile’s written submission (like the written statements from Lebanon, South Africa, and Belize) does mention peremptory norms, but it does not identify the prohibition of annexations as one of them. Chile instead notes that:

the jus cogens and erga omnes character of the right of self-determination, the basic rules of international humanitarian law, the prohibition against the use of force, and the prohibition of racial discrimination, and other international human rights provisions including the prohibition on torture… 

Meanwhile, those who do define Israel’s conduct in this case as violative of a jus cogens norm broadly invoke other jus cogens norms, rather than the prohibition of annexations itself. Some rely on the right of self-determination. For example, Ireland’s written statement suggests that, at least in this case, forcible territorial annexations are jus cogens violations because they violate the right of the Palestinian people to self-determination. The statement explains that:

Ireland has reluctantly but unavoidably concluded that [Israel’s] activity amounts to a process of annexation and a serious breach of the right to self-determination—a peremptory norm of general international law—which cannot be justified as self-defense.

The ICJ’s 2004 advisory opinion on the Legal Consequence of the Construction of a Wall in the Occupied Palestinian Territories provides support for the claim that territorial annexations violate the right self-determination. In that opinion, the Court found that Israel’s construction of the wall in the West Bank—which the Court reasoned “would be tantamount a de facto annexation” if made permanent—impeded the Palestinian right to self-determination.

Others characterize the prohibition on annexations as derived from the prohibition of the use of force. The written submission from Belize provides, for example, that “[t]he prohibition of annexation under international law is reflected in Article 2(4) of the Charter of the United Nations.” In his oral statement on behalf of Palestine, Paul Reichler appeared to make the same point:

What about Article 2(4) of the United Nations Charter and general international law, including the prohibition on acquisition of territory by force? For the United States, apparently, the peremptory norm does not exist when it comes to Israel’s annexation and settlement of the Occupied Palestinian Territory.

 Japan’s written statement develops the Article 2(4) argument at length, drawing the connection between Russia’s invasion of Ukraine and Israel’s annexation of territory in Palestine. It concludes:

As the prohibition of threat or use of force constitutes the cornerstone of the post- war international system based on the UN Charter, the prohibition of acquisition of territory by force shall be observed in good faith, taking into account the object and purpose of the UN Charter.

The Republic of Guyana also based the prohibition on annexations largely on Article 2(4) of the UN Charter:

The prohibition on annexation of territory is a jus cogens norm of universal application and a fundamental cornerstone of the international legal order. The prohibition on the acquisition of territory through the use of force is a necessary corollary of both the sovereign equality of States and the prohibition on the use of force against the territorial integrity or political independence of any State enshrined in Article 2 of the Charter of the United Nations.

The Republic of Guyana’s written submission quotes from the Max Planck Encyclopedia of Public International Law, which describes the prohibition in these terms:

In view of the pertinent consistent and uniform State practice it is beyond any doubt that, under present international law, the prohibition of annexation and the obligation not to recognize it as lawful (Stimson Doctrine) extend beyond treaty obligations and form part of customary international law. Considering the essential relevance of these two principles in terms of the effective implementation of the prohibition of the threat or use of force as the most fundamental norm of present international law, there are convincing reasons to consider them as ius cogens norms.

Here, too, the ICJ’s 2004 Advisory Opinion provides support by describing the prohibition of annexations as a “corollary” of Article 2(4).

The Prohibition of Annexations as a Standalone Jus Cogens Norm

Finally, some states, such as Brazil and Saudi Arabia, that do identify the “prohibition of annexation by force” as a “peremptory norm of international law,” include little or no discussion or support for the assertion. Unsurprisingly, the written comments of the State of Palestine characterize the prohibition of annexations exactly as we do: a jus cogens norm, one distinct from the jus cogens norms governing the use of force and self-determination.  Palestine also emphasizes – as we do – the significance of the prohibition to the international legal system as a whole:

The fundamental principle prohibiting the acquisition of territory through the threat or use of force is thus rooted in the purpose of safeguarding two of the most fundamental values of the international system—squarely at issue in this case—namely, the illegality of territorial acquisition resulting from the threat or use of force, and the obligation to respect the right of peoples to self- determination.

The general tendency to subsume the prohibition of annexations into other norms—whether on self-determination or the use of force—is a mix of misleading, pernicious, and incomplete. Misleading because these other norms do not themselves regulate sovereign title to territory, as the prohibition of annexations does. Pernicious because subsuming it into these other norms leaves open important questions that it resolves, such as whether annexations pursuant to lawful uses of force are also lawful. (The answer, we think, is clearly that they remain unlawful.) And incomplete because the prohibition of annexations derives not just from one or the other normative project but from all three of the above normative projects together. The norm should be characterized as a jus cogens norm in its own right, not treated as a corollary to some other norm with that status.

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Manuel Sánchez Miranda says

May 2, 2024

I maintain reservations about fully endorsing the view that there currently is a jus cogens norm consisting in the prohibition of forcible annexations of territory. I remain hopeful that such a norm will emerge in the future, and articles like yours certainly help guide us in that direction. However, as a matter of lex lata, I do not think we are there yet. The jus cogens norms recognized by the International Law Commission, as identified in the annex to its draft conclusions, is quite limited for a reason. I do not think there is any other norm that enjoys such broad consensus.

For the sake of argument, however, if one were to assume that such a norm is already in place, I then wonder about the implications of this norm from the perspective of the principle of non-retroactivity. When did this jus cogens norm come into existence (roughly speaking)? And, crucially, can this norm be applied to annexations consummated in the past (perhaps, on the basis that the use of force is still ongoing)? If so, how far can we go? To my recollection, the ILC has historically been reluctant to endorse the view that a jus cogens norm applies retroactively. I wonder if you share the same view as the ILC, or if you envision your proposed framework being applied differently.

That was a nice read - your forthcoming AJIL article and this blog article - thank you.

Gregory H Fox says

May 2, 2024

The paper on which this post is based is great and the topic is just fascinating. But is it appropriate to ask the same questions about Israel's actions when the claim is de facto rather than de jure annexation? De jure may well come at some point, but now the argument is based on Israel exercising sovereign powers usually prohibited to occupiers.

Sze Hong Lam says

May 2, 2024

Thank you, Professor Hakimi and Professor Brunk, for your timely and insightful contribution.

My first question is: If the prohibition against forceful is recognized as a distinct peremptory norm, how do we understand the word 'forceful' independently? At least judging from the state practices cited in the article, the meaning of 'forceful' still has to be derived from the illegal nature of the use of force or the violation of self-determination.

My following-up question is: if the term 'forceful' should/could be determined independently (i.e. without regard to the lawfulness of the use of force), would that unnecessarily restrict the freedom for states exercising legitimate self-defense to 'exchange land for peace'? I think we can all agree that no state should recognize any peace treaty in which Ukrainian territories were ceded to Russia. However, what if the case is reversed? Shouldn't Ukraine as a defending state acquire territories from Russia as a guarantee for its safety and potential compensation under a peace treaty? If we take self-defence out of the equation and view forceful annexation as a distinct jus cogen, such a peace treaty would contradict Article 53 of the VCLT.

Lastly, if the state has the sole and exclusive right to entrench territory over which it has legal title, shouldn't the state also have the same right to forfeit such entrenchment? For example, although the forceful annexation of Goa could hardly be justified under Article 2(4) (as pointed out in your article), Portugal in fact acquiesced to the Indian annexation of Goa retroactively in 1974 following the Carnation Revolution. If 'forceful' annexation was a distinct 'jus cogens', not even Portugal alone could acquiesce to such violation, because the obligation is not only owed to Portugal but also to the international society. Goa might be an extreme example, but there are also other examples of minor territorial readjustment through acquiescence to 'forceful' incursions, as demonstrated by the famous case of Temple of Preah Vihear before the ICJ. Elevating the prohibition against 'forceful' annexation as a peremptory norm would preclude the use of acquiescence and lead to result that deviates from political reality.

Thank you.

Mary Ellen O'Connell says

May 3, 2024

Dear Ingrid and Monica,

I very much appreciate your attention to the illegality of forcible annexation of territory. But I must side with the ILC on this one and the authors of the many submissions to the ICJ you cite.

I see no admission in the ILC list. The authors in the ICJ case are citing two different jus cogens norms, both of which prevent acquisition of good title to territory as a consequence of violation.

Title to territory cannot be obtained through the use of force or through colonialism, occupation, or alien domination. Title to territory can be obtained through consent. Thus, the bar to obtaining title through unlawful conduct is a consequence of the unlawful conduct, just as the obligation to provide reparations is another common consequence of unlawful conduct.

The prohibition on the use of force is jus cogens. Colonialism, long-term occupation, and alien domination are prohibited under the jus cogens norm of self-determination. In the case of Palestine, Israel has attempted to acquire territory using both forms of prohibited, jus cogens conduct.

Bars to acquiring title to territory result from other norms, as well. Just not ones with a link to jus cogens.


Mary Ellen