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Keeping Pandora’s Box Open: Jus Cogens Norms and the Revision of the Theory of Sources

Photo Credit: United Nations Photo,

Article by Christian Delev,


The chief assembly point of scepticism in the international legal belief system has consistently been the theory of international legal sources, be it for sustaining Western-centrism, ignoring the needs of the international community as a whole, or its theoretic inconsistencies. The key challenge to the present theory remains the fundamental inconsistency between the established normative sources of international law and any voluntarist or dispositive reading of it. The fruition of jus cogens norms, particularly their recognition in international (here, here and here), regional (here) and ad hoc court jurisprudence (here), has itself led to the incorporation of peremptory (i.e. hierarchical) norm obligations owed by States to the international community within the previously authority-based theory of sources. Thus, this development has, in Linderfalk’s words, ‘opened the (sic) Pandora’s Box’ by constituting a peremptory, regulatory norm that deeply restricts States’ autonomy within a system allegedly postulated on it.

This article is written in light of the International Law Commission’s (‘ILC’) draft reports on jus cogens norms, started in 2017, to argue for the cogence of the concept. It argues that, rather than seeing their emergence as a legal conundrum that demands a return to a dispositive theory, the existence of jus cogens norms is normatively sound and has become a necessary legal development for international law to move beyond a State-centric viewpoint. It will first address two criticisms of jus cogens norms – one theoretical and the other practical. Consequently, it will argue that this normative development has been critical for recognising human dignity and the international community’s interests within general international law. However, by revealing the inconsistency within the broader theory of sources, it is argued that jus cogens norms may herald a new general theory of sources.

Addressing Challenges to Jus Cogens Norms

Even prior to their inclusion in what are now articles 53 and 64 Vienna Convention on the Law of Treaties [VCLT], jus cogens norms had been a key natural law argument that challenged the monopoly that voluntarism appeared to project in early Permanent Court of International Justice case-law, especially the Lotus and Wimbledon judgments. In Schwarzenberger’s early criticism of this development, later shared by Ian Brownlie (pp. 516–17), he famously equated it to ‘national jus cogens’, i.e., public law that in all circumstances overrides the consent of private parties in their negotiations and argued, inter alia, that at the time no ‘de lege lata’ evidence or criteria existed to demonstrate what would or could constitute a jus cogens norm following existing customary international law, especially amongst existing international legal principles and regimes.

In responding to this concern, it must first be recognised that while the International Law Commission purposely avoided defining what constitutes jus cogens norms, particularly given their relative novelty at the time that the VCLT provisions had been drafted, the importance attached to the international community is clearly illustrated, for instance in State delegations’ express mention to the international community and even direct references to ‘a general multilateral treaty’ as ways to modify existing jus cogens norms in the respective VCLT provisions’ travaux preparatoires (paras 2–4). While the space remains for further clarification concerning their identification, the ILC’s first draft report has brought some degree of clarity to this. The basic characteristics of a jus cogens norm, per draft conclusion 4, are that it is 1) a ‘norm of general international law’, most commonly customary international law (draft conclusion 5(2)), that 2) ‘must be accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted’. It must be recognised, of course, that while the approach has indeed brought some clarity, new questions arise, namely how a court may methodologically determine the international community’s ‘acceptance and recognition’ given the degree of silence and also the methodology for interpreting their developing content. One potential answer borrowed from customary international law scholarship, would be by using ‘induction’ for identification and ‘deduction’ for interpretation.

While similar theoretic questions relating to jus cogens norm identification abound, it is important to also discuss the application of jus cogens norms within general international law. Linderfalk thus argued that the very consequences of jus cogens norms go beyond the reasonable expectations of any ‘international actors’. In taking the case of the prohibition on the use of force, he first discusses that the legal norm, which can be expressed in both practice and treaties, must not only be construed in light of the explicit prohibition, but also taking into account existing exceptions, such as UN Security Council decisions taken under Chapter VII UN Charter and the coexisting customary international law and UN Charter self-defence exceptions in cases of ‘armed attack’. By claiming that both exceptions might prevent the jus cogens norm from being enforced and, moreover, arguing that the self-defence exception, an aspect of a jus cogens norm itself, is restricted by other international humanitarian law jus cogens norms, Linderfalk concludes that these inter-relations are increasingly becoming unfathomable. While this picture would appear complex and almost paradoxical given the complex definition of the prohibition on the use of force and the projected overlap between two peremptory norms, this need not be so. Provided, as Linderfalk himself claims, that norms are ‘not to be identified with the utterance or utterances by which we assume the norm to be expressed’ (p 857), it can be claimed that the jus cogens norm in question must be systemically interpreted to mean the ‘prohibition of (unjustified) use of force’. Consequently, any ‘justification’ must itself be read in light of the relevant normative context, expressed in multilateral treaties (e.g. the UN Charter) and customary international law, which itself is restricted by other peremptory norms, for instance, international humanitarian law jus cogens norms.

A Straw in the Wind?

While the theoretical footing of jus cogens norms is itself sound, their application bears witness to the restraints posed by broader international law. However, while the existence of jus cogens norms is not itself a panacea against all violations – as witnessed in the Armed Activities (DR Congo v Rwanda) (para 64) and Jurisdictional Immunities (paras 92–97) cases – the present theory of sources itself is not a palladium against their enforcement. As peremptory norms have gained prominence within regional human rights court systems, so too has the drive for consistency between legal sources grown beyond the subject of academic debate. Advancements in the International Law Commission’s work on the formation of customary international law has – not without controversy – recognised that ‘practice’, one of the two components of customary international law, extends beyond State practice and partially recognises the practice of International Organisations. Through the clarification of the theory underlying customary international law, especially in light of the international community’s interest, theorists are provoked to make sweeping changes in the grand theory of sources. The serious consideration of jus cogens norms as a source of international legal obligations may indeed further challenge the dispositive turn.


While the challenges to the comprehensibility, plausibility, and validity of jus cogens norms are largely moot, they augur a visible paradigm shift within international law: a movement from holding State sovereignty as the cornerstone of the theory of sources to recognising the slowly emerging international community. Through the gradual application and clarification of the theory of jus cogens norms, so too can the general ontology of a new accepted theory of sources emerge.

About the Author: The author is an LLM candidate at Hughes Hall, University of Cambridge, and Executive Blog Editor at the Groningen Journal of International Law. He recently graduated summa cum laude from the LLB International and European Law programme at the University of Groningen, the Netherlands.