- Jus cogens rules have the highest status in the informal hierarchy of souces of IL.
- Difference between jus cogens and erga omnes rules.– The main difference btw a rule of jus cogens and a rule that creates an obligation erga omnes is that all jus cogens rules create erga omnes obligations, but only some rules creating erga omnes obligations are rules of jus cogens.
- Requirements: it must be accepted and recognised by the international community of States as a whole as a rule from which no derogation is permitted; and which can be modified only by a subsequent norm of general international law having the same character.
- Effects: States cannot deviate from jus cogens rule. A new State must accept it and it cannot be changed without the approval of the international community as a whole.
- Regulation: article 53 VCLT. Definition (art. 53 VCLT): ‘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 53 VCLT provides that a treaty is void if, at the time of its conclusion, it conflicts with a peremptory rule of international law. As to an existing treaty, under Article 64 VCLT if a new rule of jus cogens emerges and a treaty conflicts with it, the treaty becomes void and terminates. However, specific procedures set out in Articles 65 and 66 VCLT must be followed if a party to a treaty claims that the existing treaty breaches a new established in accordance with the procedures contained in article 65 and 66 VCLT. Consequently, a party to a traty must follow these procedures in order to invalidate it while a State, or an IGO, which is not a party to a treaty, is not required to follow them and therefore may claim that a particular treaty is invalid on the ground that it clashes with a jus cogens rule. An example of a situation where a treaty was invalidated on the ground of a violation of jus cogenes providedad by the IACtHR in Aloeboetoe Case.
- The VCLT does not freeze the rules of jus cogens. To the contrary, its article 64 highlights the evolutionary nature of jus cogens. It states that ‘if a new peremptory norm of general law emerges any existing treaty which is in conflict with that norm becomes void and terminates’. However, in practice it is difficult to envisage a situation where a new rule of jus cogens would overturn an existing rule bearing in mind that by their nature jus cogens rules are not only accepted but also recognised by the international community of States as a whole.
- The international community has not agreed on any list of peremptory rules. However, in the case Concerning Questions relating to the obligation to extradite or prosecute (Belgium v. Senegal) the ICJ suggested that in order to identify a rule of jus cogens, procedures similar to those relating to the identification of any rule of customary law should be carried out.
Assesment of jus cogens
In the light of more recent judgements of the ICJ the role of jus cogens seems to be undermined rather than enhanced.
- The prohibition of torture: In the Case Concerning Questions Relating to the Obligation to Extradite or Prosecute (Belgium v. Senegal.
- Rules relating to State immunity are rules of procedure, jus cogens are rules of substance. Conflict btw them conceptually impossible.
- Erga omnes obligations. In the Barcelona Traction, Light and Power: the ICJ making reference to these erga omnes obligations stated that: ‘Such obligations derive, for example, in contemporary International Law, from the outlawing of acts of aggression, and of genocide, and also from the principles and rules concerning the basic rights of the human peron, including protection from slavery and racial discrimination.
- The 2005 Resolution of the Institute of International Law examines erga omnes obligations: the prohibition of acts of aggression, the prohibition of genocide, obligations concerning the protection of basic human rights, obligations relating to the environment of common space