Return to Mount Olympus: ‘Legal Polytheism’, Jus Cogens Norms, and the Conflict in Ukraine

Author: Francisco Lobo

“Lawyers and judges seem to disagree very often about the law governing a case; they seem to disagree even about the right tests to use”. These words were once written by a prominent legal theorist, Ronald Dworkin, who believed that at the heart of legal argument we find contestation between what he called different “propositions of law”. This is no less the case when we talk about the legal sub-regime known as international law. In this short piece I will call ‘legal polytheism’ that particular kind of contestation we find in legal argument as applied to a specific category of legal rules, peremptory norms of general international law, also known as jus cogens rules. Since these rules are varied in content and, at the same time, enjoy the same legal hierarchy, different propositions of law may draw on them to argue diverse and sometimes incompatible claims, for which there is no ‘theological’ or top-down solution as these standards are deemed equally important.

Jus cogens rules are defined in the 1969 Vienna Convention on the Law of Treaties (Art. 53) as “a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character”. The treaty, however, does not provide examples of such rules, as it only spells out the formal consequences of a breach of said standards, namely the nullity of a treaty that contravenes them.

During recent years, the International Law Commission (‘ILC’, the UN agency of experts in international law) has been working on a full study of peremptory norms of general international law, or jus cogens norms, wherein it has further characterized them as standards that reflect and protect fundamental values of the international community and that are both universal and hierarchically superior to every other rule of international law. To further illustrate this, the ILC has compiled a non-exhaustive list of examples of jus cogens norms, including the following: a) the prohibition of aggression; b) the prohibition of genocide; c) the prohibition of crimes against humanity; d) the basic rules of International Humanitarian Law (‘IHL’, especially the prohibition of war crimes); e) the prohibition of racial discrimination and apartheid; f) the prohibition of slavery; g) the prohibition of torture; and h) the right of self-determination.

The varied propositions of law that states wield in the international arena have come to resemble a form of secular, legal polytheism whereby each country “prays” to the god or gods that suit them best.

Several states have reacted to this list at the UN level, with some celebrating it – such as Belgium, Colombia, and South Africa – and others criticizing it – for instance France, Israel, and the United States. Other states have followed a more nuanced path, such as Austria, a country that welcomes the drafting of an illustrative list but remains concerned about its lack of precision. This ostensible polarization may be explained by the fact that some states prefer to reduce formal limitations arising from international law as much as possible such that they can have more leeway to maneuver in the field of international relations. Since jus cogens rules acts as limitations of ‘public order’ on the free will of states – a phenomenon also known as ‘contractual jus cogens – it is understandable that some states prefer to safeguard their freedom by delineating these boundaries as clearly as possible.

But whatever position states have adopted vis-à-vis the existence of a list, the truth is that they often include jus cogens contents in their “propositions of (international) law”. However, since there are several examples of rules that exhibit the same hierarchy and importance for the international community, and there being no ‘father of the gods’ figure to adjudicate disputes between such equally important norms, tensions and clashes between those standards remain a permanent possibility for which no normative – or political – solution exists at the moment. In other words, the varied propositions of law that states wield in the international arena have come to resemble a form of secular, legal polytheism whereby each country “prays” to the god or gods that suit them best at a given time, whereby each item from the illustrative list acts as a deity that is conjured up to make a legal argument, states being able to choose among the members of this pantheon the one or ones that work best to ground their propositions of law.

Such contestability of propositions of international law has been most recently borne out of the ongoing war in Ukraine, where we have witnessed how the parties to the conflict pray to different gods from the jus cogens list, or even the same ones but with different readings of what they stand for. Thus, Ukraine and its allies in the West rely on the prohibition of aggression and its correlative right of self-defense to justify its resistance against the Russian invasion, as well as on the right of self-determination to be free of foreign oppression. They are also committed to prosecuting war crimes perpetrated by Russian forces, that is, punishing grave breaches of the basic rules of IHL.

Russia, on the other hand, even though it has also criticized the non-exhaustive list, still draws on some of its items to build its propositions of law, including also the right of (preventive) self-defense against an alleged impending aggression from the West, and a particularly vicarious reaffirmation of the right to self-determination of the people of eastern Ukraine. Arguably, one of the basic rules of IHL, the principle of military necessity, has also been relied on by Russia often during its military campaign.

But perhaps nowhere is this contestability and protean nature of jus cogens rules better reflected than in the legal dispute between Russia and Ukraine over the prohibition of genocide. Indeed, only a few days after the Russian invasion, Ukraine filed an application instituting proceedings against Russia before the International Court of Justice for a breach of the 1948 Genocide Convention. Ukraine’s claim, or proposition of law, is that Russia has misapplied and abused the Convention by using it as an excuse to build its casus belli to use force against Ukraine, in order to prevent an alleged genocide of ethnic Russians in Luhansk and Donetsk, with no basis in reality. This is further evidence that, even when conjuring up the same jus cogens god, in this case the prohibition of genocide, states can still face profound disagreement in their propositions of law.

It remains to be seen what the high priests sitting at the International Court of Justice will rule after both parties have submitted their full written pleadings (due in September of 2022 for Ukraine and March of 2023 for Russia) and argued their cases in future oral hearings, which could take years. In the meantime, the Court has already issued a decision containing some provisional measures, ordering Russia to immediately suspend its military operations in Ukraine. We can only hope that all violations of international law in this case have serious consequences, including punishment for war crimes and the duty not to recognize Russia’s illegal gains. Let us pray to all the gods.

About the author: Francisco Lobo is a Doctoral Researcher in the Department of War Studies at King’s College London. He holds an LL.M. in International Legal Studies from NYU, an LL.M. in International Law and LL.B. from the University of Chile. Contact:


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