What Is Jus Cogens in International Law and What Are Its Implications for Treaties and State Conduct?

Japanese Attorney at Law - Bengoshi L.L.

• 8 min read

In the intricate web of international law, most rules are formed through the consent of states, primarily via treaties and customary international law. States are generally free to create new rules or modify existing ones. However, a special category of norms, known as peremptory norms of general international law, or jus cogens, stands apart. These are fundamental principles, recognized by the international community of States as a whole, from which no derogation is permitted. This article delves into the concept of jus cogens, how such norms are identified, and their profound implications for international agreements and state behavior.

The Concept and Nature of Jus Cogens

The modern doctrine of jus cogens is most authoritatively defined in Article 53 of the Vienna Convention on the Law of Treaties (VCLT) 1969:

"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."

Several key characteristics emerge from this definition:

  1. Peremptory Nature: Jus cogens norms are overriding principles of international law. States cannot "contract out" of them or create rules that conflict with them.
  2. Universal Applicability: They are norms of general international law, binding on all states.
  3. Recognition by the "International Community of States as a Whole": This signifies a very high threshold for a norm to achieve jus cogens status. It requires widespread acceptance across different regions, legal systems, and cultures, not merely a simple majority of states. It does not necessarily mean unanimous consent from every single state, but rather a very large majority where any dissent does not undermine the norm's fundamental character.
  4. Non-Derogability: No derogation is permitted. This distinguishes jus cogens from ordinary customary international law, which states can deviate from by treaty or by the formation of a new, conflicting custom (unless the original custom was itself jus cogens).
  5. Modification: A jus cogens norm can only be modified by a subsequent norm of general international law that has the same peremptory character.

Philosophically, jus cogens reflects the idea that the international legal order is not purely based on state consent but also incorporates fundamental values and principles essential for the maintenance of international public order and the protection of the vital interests of the international community. It introduces a form of "international public policy" or a "higher law" into the system. Its roots can be traced to natural law concepts, emphasizing universally binding moral and ethical principles, and it gained significant traction in the post-World War II era, driven by the desire to prevent atrocities and uphold fundamental human dignity.

Identifying Jus Cogens Norms

Despite its importance, there is no universally agreed-upon definitive list of jus cogens norms, nor is there a formal, institutionalized procedure for their identification. The determination that a norm has achieved jus cogens status is typically a result of a process involving state practice, opinio juris (the belief that the norm is legally binding and peremptory), pronouncements by international courts and tribunals, and the work of authoritative bodies like the International Law Commission (ILC).

The ILC, in its recent work on peremptory norms (culminating in Draft Conclusions adopted in 2019 and Commentaries thereto adopted in 2022), has provided valuable guidance on the criteria and evidence for identifying jus cogens norms. The ILC's Draft Conclusion 4 emphasizes that a norm must be a norm of general international law and must be accepted and recognized by the international community of States as a whole as one from which no derogation is permitted and which can only be modified by a subsequent norm of the same character. Evidence for such acceptance and recognition can be found in a wide range of materials, similar to those used for identifying customary international law, but with a focus on the peremptory character of the norm.

Widely Recognized Examples of Jus Cogens Norms:
While a definitive list is elusive, a consensus exists or is emerging around several norms as having jus cogens status. The ILC's work includes an annex providing a non-exhaustive list of norms previously referred to by the Commission as having this status, and which international courts and tribunals have also widely recognized:

  • The prohibition of aggression (or unlawful use of force): This is perhaps the most fundamental jus cogens norm, underpinning international peace and security. The International Court of Justice (ICJ) has implicitly recognized its peremptory character.
  • The prohibition of genocide: Explicitly recognized as jus cogens by the ICJ in Armed Activities on the Territory of the Congo (New Application: 2002) (Democratic Republic of the Congo v. Rwanda) (Jurisdiction and Admissibility, Judgment of February 3, 2006).
  • The prohibition of slavery and the slave trade.
  • The prohibition of torture and other cruel, inhuman, or degrading treatment or punishment: Recognized as jus cogens by the International Criminal Tribunal for the former Yugoslavia (ICTY) in Prosecutor v. Furundžija (Trial Chamber Judgment, December 10, 1998) and the European Court of Human Rights (ECHR) in Al-Adsani v. The United Kingdom (Judgment of November 21, 2001).
  • The prohibition of piracy.
  • The prohibition of racial discrimination and apartheid.
  • The right to self-determination of peoples: The ICJ has referred to the right of self-determination as a right erga omnes (owed to the international community as a whole), and many consider its core components to be of jus cogens character.
  • Basic rules of international humanitarian law: Certain fundamental rules applicable in armed conflict are also widely considered to be jus cogens.

The threshold for a norm to attain jus cogens status is high, reflecting its exceptional and overriding nature.

Consequences of Jus Cogens in International Law

The peremptory character of jus cogens norms carries significant legal consequences across various areas of international law.

A. Impact on Treaties

This is the most clearly defined area of jus cogens' effect, primarily governed by the VCLT:

  • Nullity of Conflicting Treaties (VCLT Article 53): "A treaty is void if, at the time of its conclusion, it conflicts with a peremptory norm of general international law." This means such a treaty has no legal force from the outset (ab initio).
  • Termination of Treaties Conflicting with New Jus Cogens (VCLT Article 64): "If a new peremptory norm of general international law emerges, any existing treaty which is in conflict with that norm becomes void and terminates." The termination here is prospective; rights and obligations accrued before the emergence of the new jus cogens norm are not necessarily affected, unless the norm itself dictates otherwise.
  • Reservations to Treaties: A reservation to a treaty provision that reflects a jus cogens norm is generally considered impermissible if it would allow the reserving state to derogate from that norm.

B. Impact on State Conduct and Responsibility

While the VCLT focuses on treaties, jus cogens norms also have profound implications for general state conduct and the law of state responsibility:

  • Obligations Erga Omnes: Many, if not all, jus cogens norms give rise to obligations erga omnes. These are obligations owed not just to a particular state, but to the international community as a whole. All states are considered to have a legal interest in their protection. The ICJ first articulated this concept in the Barcelona Traction, Light and Power Company, Limited (Belgium v. Spain) case (Second Phase, Judgment of February 5, 1970). While closely related, jus cogens refers to the peremptory character of a norm, while erga omnes refers to the scope of its applicability and opposability.
  • Serious Breaches of Obligations Arising from Jus Cogens Norms: The ILC Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA) outline specific consequences for "serious breaches" (defined as gross or systematic failure) of obligations arising under peremptory norms of general international law (ARSIWA Articles 40 and 41). These consequences apply to all states, not just the injured state, and include:
    • A duty for all states to cooperate to bring the serious breach to an end through lawful means.
    • A duty for all states not to recognize as lawful a situation created by a serious breach.
    • A duty for all states not to render aid or assistance in maintaining that situation.
      The ICJ affirmed these duties in its Advisory Opinion on the Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (July 9, 2004).

C. Impact on State Immunity and Jurisdiction

This remains one of the most contentious and developing areas concerning jus cogens. The question is whether a state or its officials can claim immunity from jurisdiction (particularly of foreign national courts or international tribunals) for acts that violate jus cogens norms.

  • State Immunity in Civil Proceedings: The prevailing view, affirmed by the ICJ in the Jurisdictional Immunities of the State (Germany v. Italy: Greece intervening) case (Judgment of February 3, 2012), is that customary international law does not currently provide for an exception to state immunity in civil proceedings before foreign national courts solely on the ground that the acts alleged constitute violations of jus cogens (such as war crimes or crimes against humanity). The ICJ reasoned that the rules on state immunity are procedural in nature and are distinct from the substantive rules of jus cogens, and that no conflict between them arises. This has been a point of considerable debate, with some national courts (notably in Italy, as in the Ferrini v. Federal Republic of Germany case, Court of Cassation, March 11, 2004) taking a contrary view, arguing that jus cogens should prevail over immunity.
  • Immunity of State Officials:
    • Immunity Ratione Personae (Personal Immunity): Sitting Heads of State, Heads of Government, and Ministers for Foreign Affairs generally enjoy immunity ratione personae from foreign criminal jurisdiction, even for alleged jus cogens crimes, for the duration of their time in office (as held by the ICJ in the Arrest Warrant case, 2002). However, this does not mean impunity, as they can be prosecuted by their own national courts, if their state waives immunity, after they leave office (for acts not covered by functional immunity), or by competent international criminal tribunals.
    • Immunity Ratione Materiae (Functional Immunity): For former officials, or for official acts of incumbent officials not covered by personal immunity, the question is whether functional immunity applies to jus cogens crimes. The Pinochet cases (UK House of Lords, 1998-1999) suggested that international crimes like torture, prohibited by jus cogens and international conventions, cannot be considered legitimate official functions deserving of immunity ratione materiae. This remains an area of development.
  • Universal Jurisdiction: Many jus cogens crimes (e.g., genocide, war crimes, crimes against humanity, torture) are also subject to universal jurisdiction, meaning states may be entitled (or in some cases, obliged by treaty) to prosecute offenders regardless of where the crime was committed or the nationality of the perpetrator or victim.

D. Other Implications

  • Invalidity of Other International Acts: Acts of international organizations (e.g., certain UN Security Council resolutions) or unilateral acts of states that conflict with jus cogens norms are likely to be considered invalid or unlawful.
  • Limitation on Customary International Law: A customary international law rule cannot develop or be applied in a manner that conflicts with a jus cogens norm.
  • Countermeasures: A state taking countermeasures in response to an internationally wrongful act by another state must not breach its obligations under jus cogens norms (ARSIWA Article 50(1)(d)).

The Role and Challenges of Jus Cogens

Jus cogens plays a vital role in the international legal system by:

  • Protecting Fundamental Values: It safeguards core values of the international community, such as peace, human dignity, and the basic rights of peoples.
  • Promoting a "Public Order" of the International Community: It introduces an element of hierarchy and objectivity into a system largely based on state consent, suggesting a move towards a more constitutionalized or value-oriented international legal order.

However, the doctrine is not without its challenges:

  • Identification Uncertainty: The lack of a precise mechanism for identifying jus cogens norms and the high threshold for their recognition can lead to uncertainty and debate about which specific norms have achieved this status.
  • Potential for Abuse: The concept could potentially be invoked for political reasons or to challenge established legal rules without broad consensus.
  • Tension with State Sovereignty and Consent: Jus cogens inherently limits state sovereignty by imposing non-derogable obligations, which can create tension with the traditional consent-based nature of international law. The ILC's work aims to mitigate some of these concerns by emphasizing the stringent criteria for a norm to be recognized as jus cogens.

Conclusion

Peremptory norms of general international law (jus cogens) represent a fundamental and increasingly significant feature of the international legal landscape. They embody the most basic values of the international community and impose overriding obligations on all states, limiting their freedom of action in treaty-making and other conduct. While challenges remain in their precise identification and the full scope of their legal consequences, particularly in areas like state immunity, the doctrine of jus cogens underscores the evolution of international law towards a system that not only regulates inter-state relations but also upholds certain universal principles essential for global order and justice. For those engaged in international affairs, awareness of these fundamental, non-derogable norms is increasingly indispensable.