International law is governed by several principles which influence its applications. One of those principles is the principle of jus cogens. Jus cogens, or Peremptory Norms as they are also referred to, are considered an important part of Public International Law. In this question, I will try to define jus cogens and look into the emergence of jus cogens as a normative category of law. Furthermore, I will look into the application of jus cogens, in law-making as well as in its application by international judicial bodies. To conclude, I will analyse whether there is a need for jus cogens in light of its seldom application.
What is Jus Cogens?
Jus cogens are recognised as an important principle of international law which cannot be derogated from. From a literal understanding of the term, deriving from its Latin phrase, it means compelling law. As is mentioned before, jus cogens are also referred to as peremptory norms.
Art. 53 of the Vienna Convention of the Law of Treaties (VCLT) defines it as follows:
For the purposes of the present Convention, a peremptory norm of general international law is 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.
Although there is agreement that there exists a principle of international law called jus cogens, there has not been an attempt to enlist what it entails. Thus, in the words of Abi-Saab, jus cogens can be thought of as a box without a clarity on what its contents, origin or sources are.
How did the normative category of jus cogens emerge?
The idea of jus cogens was part of the legal scholarship for many years. It developed as a doctrine, but it was a broad idea which made it difficult to be applied in a practical sense. It was discussed and later recognised in 1969 with the emergence of the VCLT. This was when jus cogens was introduced formally into the world of international law.
It appears twice in the VCLT, firstly, under Art. 53 which voids a treaty if it is in conflict with a peremptory norm of general international law at the time of conclusion; and secondly, under Art. 64, which voids any treaty in existence which violates a new peremptory norm that has emerged.
But there is a debate on whether jus cogens is created by way of a treaty or through the emergence of custom.
Application of Jus Cogens – or Reasons why it is not used:
Jus cogens are often used synonymously with the human rights rules. In fact, in the Restatement (Third) of the Foreign Relations of the United States, many human rights norms are categorised as having achieved the standing of jus cogens.
Hierarchical Rules of Law
With the emergence of jus cogens, Art. 38(1) of the Statute of the ICJ was disturbed. Earlier, it was a belief that all of the “sources of international law” (if they can be termed as such) in the said provision were on an equal footing. But recognition of jus cogens has introduced a hierarchy of rules in the list of sources, with jus cogens placed at the top. Not only was a hierarchy created in the rules of application of the law; but this also curtailed the flexibility of the law applicable due to its content. It was now necessary to look at the content of each rule of law and assign value; whether the said rule is of higher value than the rest.
Given the situation of priority, the natural understanding is that this principle would be oft used and quoted in international law. But that is not the case as is seen in the next section.
Application by International Tribunals
The ICJ had been suspiciously quiet about jus cogens and its applicability. Since its formal acceptance into the realm of international law in 1969 through VCLT, it took the ICJ almost 3 decades to discuss to jus cogens.
In the Advisory Opinion of 1996 regarding the Legality of Use or Threat of Use of Nuclear Weapons, the term “jus cogens” was not used. Instead, the court equated it with humanitarian law as “intransgressible principles of humanitarian law”. Even when it acknowledged the existence of peremptory norms as envisaged in the ILC, the court created a separate category. This category was the violation of erga omnes rather than accept jus cogens as an existing normative category. Thus it is clear that the ICJ hesitated in recognising and later applying this principle.
In the case of Armed Activities on the Territory of the Congo, the ICJ recognised the principle of jus cogens and weighed it against the concept of “consent of parties”. Although it recognised the peremptory norm, the court ruled that such a norm cannot be used to trump the consent requirement to establish the jurisdiction of the Court. Judge Dugard’s opinion sheds more clarity, stating that a judicial decision is a choice guided by principles, identified as ‘propositions that describe rights’, and policies, namely ‘propositions that describe goals.’It was accepted that as jus cogens are based on both policy as well as principles, it would enjoy a higher value.
One of the reasons for the hesitation by the ICJ to apply this principle would be to recognise a law which was not created by it. Another reason could be that when recognised, jus cogens would have to be strictly applied. In that context, Judge Dugard’s opinion of the existence of jus cogens in a contextual manner with limitations seems to strike the right balance between the existence and non-existence of jus cogens.
To summarise, it can be seen that the trend of application of jus cogens is limited at the tribunals. This can be attributed to the rigidity of a concept of jus cogens, the consequence of voiding a treaty (VCLT Art. 53 and 64) and the unlimited power that is accumulated in its application when a norm is recognised as jus cogens.
Critical Analysis – Is jus cogens then needed when it is seldom applied in practice?
The concept of jus cogens, as is observed, has not been accepted with open arms by the Tribunals (particularly ICJ). In the context of limited application, a question might arise that there is no need for the concept of jus cogens. But taking away this principle would strike at the communitarian values that are being compiled in international law. Judge Dugard’s opinion can be used to shift the application of jus cogens from a mechanical application of the law to a flexible concept which is used as an interpretive tool between competing norms.
Ultimately, jus cogens are a construct of society. Its value is based on the value placed on it by the community, including the hierarchical priority. Just like Mana, jus cogens is an abstract and general concept which is quite concrete. A flexible interpretation can replace the rigid application. This can ensure that the principle is used more often in practice.
 Art. 53, VCLT
 Bianchi, A. ‘Human Rights and the Magic of Jus Cogens’ 19 European Journal of International Law 491-508, 494 (2008).
 Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, I.C.J. Reports 2004, p. 136, para.159
 Armed Activities on the Territory of the Congo (New Application: 2002) (Dem. Rep. Congo v. Rwanda), Jurisdiction and Admissibility  ICJ Rep 1, Separate Opinion of Judge ad hoc
 Bianchi, A. ‘Human Rights and the Magic of Jus Cogens’ 19 European Journal of International Law 491-508, 503 (2008).
 Prosecutor v. Anto Furundzija, IT-95-17/1-T, ICTY Trial Chamber II, Judgment of 10 Dec. 1998, at paras 155-156