International Law
Jus Cogens and Obligations Erga Omnes in International Law
Most rules of international law can be set aside by agreement between states. A small core cannot: these are peremptory norms, or jus cogens. Some obligations are also owed not to a particular state but to the international community as a whole: these are obligations erga omnes. The two ideas overlap but answer different questions. This note explains each, with the leading texts and cases.
1. Jus Cogens: Meaning
- Article 53, VCLT. A treaty is void if, at the time of its conclusion, it conflicts with a peremptory norm of general international law, that is, a norm accepted and recognised 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.
- Article 64, VCLT. If a new peremptory norm emerges, any existing treaty in conflict with it becomes void and terminates.
- Features. Accepted by the community of states as a whole, not by each state individually; binding on all states; incapable of derogation by treaty, local custom or persistent objection; changeable only by a new norm of the same character.
- Procedure. Under Article 66(a), a dispute over Articles 53 or 64 may be submitted to the ICJ; under Article 44(5), the offending treaty is void in whole, with no severance of clauses.
- Origins. Writers such as Verdross developed the idea before the Second World War; the 1969 Convention was the first treaty to codify it.
2. Which Norms Are Peremptory?
Figure 1: Non-exhaustive list annexed to the ILC conclusions, 2022
On 17 May 2022, the International Law Commission adopted on second reading 23 draft conclusions on the identification and legal consequences of peremptory norms. The annex lists, without claiming to be complete, the prohibitions of aggression, genocide, crimes against humanity, racial discrimination and apartheid, slavery and torture, the basic rules of international humanitarian law, and the right of self-determination.
- Prosecutor v Furundžija (ICTY, 1998). The prohibition of torture is a peremptory norm.
- Armed Activities (DRC v Rwanda), 2006. The ICJ expressly recognised the prohibition of genocide as jus cogens for the first time, but held that this did not by itself give it jurisdiction.
- Belgium v Senegal, 2012. The prohibition of torture is part of customary international law and has become a peremptory norm.
- Jurisdictional Immunities (Germany v Italy), 2012. Rules of state immunity are procedural and do not conflict with substantive peremptory norms, so Germany retained immunity in Italian courts despite serious violations during the Second World War.
3. Consequences
Figure 2: Consequences of a peremptory norm
4. Obligations Erga Omnes
- Barcelona Traction (Belgium v Spain), 1970. The Court distinguished obligations of a state towards another state from obligations towards the international community as a whole; the latter, by their nature, concern all states, and all states have a legal interest in their protection; examples include the outlawing of aggression and genocide and the basic rights of the human person, including protection from slavery and racial discrimination.
- East Timor (Portugal v Australia), 1995. The right of self-determination has an erga omnes character, but that character and the rule of consent to jurisdiction are different things; the Court could not decide without Indonesia, an absent third state.
- Wall advisory opinion, 2004. Self-determination and certain obligations of humanitarian law are erga omnes; all states must not recognise the illegal situation or aid in maintaining it.
- Erga omnes partes. Obligations under some treaties are owed to all parties; any party may bring a claim without being specially affected (Belgium v Senegal, 2012, under the Torture Convention; The Gambia v Myanmar, 2022, under the Genocide Convention)
- Article 48, ARSIWA. A state other than the injured state may invoke responsibility if the obligation is owed to a group of states for their collective interest, or to the international community as a whole.
5. Jus Cogens and Erga Omnes Compared
Figure 3: Two concepts, two questions
⚠ Exam trap Jus cogens concerns validity: a treaty conflicting with a peremptory norm is void (Article 53) or becomes void (Article 64), and no persistent objector exception applies. Erga omnes concerns standing: every state may invoke the breach (Barcelona Traction, 1970; Article 48, ARSIWA). Neither creates jurisdiction without consent (East Timor, 1995; Armed Activities, 2006). The ILC adopted its conclusions on peremptory norms on 17 May 2022. |
6. Frequently Asked Questions
Can a persistent objector escape a peremptory norm?
No. A peremptory norm is accepted by the international community as a whole and binds every state; the persistent objector rule applies only to ordinary custom.
Does a breach of jus cogens remove state immunity?
Not according to the ICJ. In Germany v Italy (2012), it held that immunity rules are procedural and do not conflict with substantive peremptory norms, so immunity is not lost because the underlying acts were grave violations.
7. Related Topics
- Topic 8: International Custom. The persistent objector.
- Topic 16: Law of Treaties IV. Invalidity of treaties.
- Topic 43: State Responsibility. Serious breaches and countermeasures.