What is Jus Cogens in International Law?

Jus Cogens - Show Notes 

It means “a mandatory or peremptory norm of general international law accepted and recognized by international community as a norm from which no derogation is permitted. 

Grotius relied heavily on Roman Law distinction between jus strictum (Obligatory Law) and jus dispositivum (Voluntary Law). 

Thinking of early International Law scholars was heavily dominated by voluntarist approaches. 

1928 – Pablo Najera (French-Mexican Claims Commission) 

1934 – Individual opinion by Judge Schucking of PCIJ in 1934 Oscar Chinn Case. 

Article 53 of VCLT - Treaties conflicting with a peremptory norm of general international law (“jus cogens”) 

“A treaty is void if, at the time of its conclusion, it conflicts with a peremptory norm of general international law. 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.” 

Article 64 of VCLT - Emergence of a new peremptory norm of general 

international law (“jus cogens”) 

“If a new peremptory norm of general international law emerges, any existing treaty which is in conflict with that norm becomes void and terminates.” 

Thus, the Jus Cogens Rule trumps the relevant treaty in question, rendering it void in entirety. 

Today, Jus Cogens is widely accepted among the scholars of International Law. 

Lauterpacht wrote that “the concept of Jus Cogens operates as a concept superior to both customary international law and treaty. 

Therefore, a jus cogens rule may thus override even the most authoritative form of executive action known to international society, should that authority be exercised in violation of that rule. 

In addition to the prohibitions against the aggressive use of force and genocide, rules which are today widely accepted as being rules ofjus cogens include the prohibitions against slavery, torture and apartheid.26 These rules play an essential role in the international legal system by defining certain key aspects of that system and making it extremely difficult for States to change the way these rules apply to them. 

Opinio Juris seems to be at the root of the non-derogable character of Jus Cogens Rules because States simply do not believe that it is possible to contract out of Jus Cogens Rules. 

Most scholars believe that the principal source of Jus Cogens Rules is the process of Customary International Law.