Author: Sué González Hauck

Required knowledge: Link

Learning objectives: Understanding XY.

A. Introduction


Consent is at the heart of the international legal system. The degree to which it is taken to structure the international legal system as a whole depends on whether and to what degree one subscribes to voluntarist theories of validity of international legal rules. The famous Lotus case is the often-cited symbol and point of anchoring for such voluntarist conceptions of international law. The often-cited passe of the Lotus dictum in this context reads:

International law governs relations between independent States. The rules of law binding upon States therefore emanate from their own free will as expressed in conventions or by usages generally accepted as expressing principles of law and established in order to regulate the relations between these co-existing independent communities or with a view to the achievement of common aims. Restrictions upon the independence of States cannot therefore be presumed.[1]

Consent is thus supposed to be the expression of the 'free will' of a sovereign state and the source of obligations under international law. The principle of consent is reflected in the way international law is formed. This is most obvious in the cases of treaties, which are, in principle, only binding on a state if this state has expressed its consent to be bound by the respective treaty (cf. Articles 11-17 VCLT). Consent is also an essential part of international dispute resolution. Under Article 36 of the Statute of the ICJ, states can accept the ICJ's jurisdiction either by signing the ICJ Statute, or by making a special declaration recognizing the ICJ's jurisdiction in a particular case. This means that a state can only be brought before the ICJ if it has consented to the ICJ's jurisdiction either generally or specifically in a particular case.

Two main issues arise regarding this conception of the role of consent in international rule-making: First, given that States are legal entities who cannot form and express a 'free will' in the same way an individual person can, the question of whether and how one can attribute a free will to a State and which expressions of such an attributed will count as expressions of State consent remains one of the enigmas at the heart of international law. Second, the prevailing formalized conception of consent, which flows from the idea of sovereign equality among States, does not take into account material inequalities.

It is commonplace among international lawyers to juxtapose an extreme version of a voluntarist conception of international law, in which consent and only consent is supposed to be the source of obligations under international law, to a conception of international law based on community values. According to Martti Koskenniemi, this contrast between consent and justice is but one of the many ways in which international legal arguments permanently oscillate between 'concreteness' and 'normativity'.[2]

B. Consent, Consensus, and Anarchy


The importance of consent in international law stems from the fact that there is no international government. The absence of government or hierarchical rule in the sense of a centralized authority that can make and enforce laws can be defined as anarchy.[3] The absence of centralized government does not entail the absence of order or rules. In the absence of formal hierarchical rule and thus under conditions of formal equality, the subjects of international law, i.e. mainly States, can only be bound by a rule of international law if they have given their consent. This mirrors the ideal of consensual decision-making and unanimity, which communal anarchist theories embrace. These theories were developed with smaller communities of individuals in mind, not with a global community of States. The difference between this community-oriented idea of anarchy on the one hand and the notion of anarchy, which prevails on the international plain and which focuses on the sovereignty of individual States on the other hand marks the difference between group-oriented notions of consensus and unanimity and individualist voluntarist notions of consent.


Stephen Neff distinguishes three kinds of consent: ‘outcome consent’, ‘rule consent’, and ‘regime consent’.[4] Outcome consent refers to a specific situation and it transforms the outcome of this situation. An act that would otherwise be unlawful is transformed into a lawful act due to the fact that the state affected by this act has given its consent. Rule consent refers to the voluntary acceptance of a specific rule of international law. This kind of consent is at the basis of classical positivist and voluntarist conceptions of international law sources and of international law’s validity. Regime consent refers not to a specific rule but, more generally, to a be bound by the rules created within a specific system, e.g. international organization. In the terminology introduced by HLA Hart, rule consent can be characterized as consent to primary rules, i.e. rules involving substantive obligations, while regime consent refers to secondary rules, i.e. rules about rule-making. [5] Arguments involving a generalized kind of consent to the whole of international law have played a key role in the era of formal decolonization, i.e. mainly in the 1960s and 1970s. The ‘newly independent states’ that were created as a result of this formal decolonization argued that they had not consented to previously existing international legal rules and could therefore start with a clean slate. The counterargument, which prevailed, was based on a form of regime consent: International lawyers from the Global North argued that the newly independent states had given a generalized consent to the international legal system by attaining independence as states.


State consent obtained its status as the ultimate source of international legal obligations in the nineteenth century, as international law was established as a 'scientific' discipline and as legal positivists purportedly broke ties with the natural law tradition. The nineteenth century was also the time during which European States formalized their colonial endeavours. Consent as a foundational principle of international law was supposed to flow from State sovereignty. Consequently - but not incidentally - there was no place in nineteenth-century positivist accounts of international law for consent of people and communities that were not organized in the form of European States.[6]

On the other hand, colonial powers used a formalized notion of consent to legitimize their claim to colonial domination. While European States did not recognize indigenous polities in the Americas, Africa, and Australia as sovereign entities with the power to contribute to international law-making and with the protection that the principle of non-intervention and other corollaries of sovereignty provide, they did recognize indigenous authorities and their capacity to enter into legally binding obligations when it came to formally ceding title to land. This practice entirely neglected the coercive circumstances that accompanied formal declarations of consent.[7]

Contemporary international legal rules take into account indigenous peoples's rights by requiring their free, prior, and informed consent regarding policies and projects that directly affect them. Key international instruments that explicitly guarantee the right to free, prior, and informed consent for indigenous peoples include the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP), International Labour Organization Convention 169 (ILO 169, Article 6), and the Convention on Biological Diversity (CBD, Article 10(c)). According to Article 19 UNDRIP, 'States shall consult and cooperate in good faith with the indigenous peoples concerned through their own representative institutions in order to obtain their free, prior and informed consent before adopting and implementing legislative or administrative measures that may affect them'. The UN Office of the High Commissioner for Human Rights has published the following guidelines on the meaning of free, prior and informed consent:[8]

Free implies that there is no coercion, intimidation or manipulation.

Prior implies that consent is to be sought sufficiently in advance of any authorization or commencement of activities and respect is shown to time requirements of indigenous consultation/consensus processes.

Informed implies that information is provided that covers a range of aspects, including the nature, size, pace, reversibility and scope of any proposed project or activity; the purpose of the project as well as its duration; locality and areas affected; a preliminary assessment of the likely economic, social, cultural and environmental impact, including potential risks; personnel likely to be involved in the execution of the project; and procedures the project may entail. This process may include the option of withholding consent. Consultation and participation are crucial components of a consent process.


The most important limits on state consent under contemporary positive law are jus cogens according to Article 53 VCLT and Article 103 of the UN Charter. Both of these norms establish a hierarchy of rules by limiting states' ability to enter into and uphold agreements that conflict either with jus cogens or with the UN Charter.[9] Jus cogens, or a peremptory norm of general international law is, according to Article 53 VCLT, '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'. This means that states cannot modify jus cogens through other treaties or through customary law. Examples of jus cogens include the prohibition of genocide, crimes against humanity, slavery, and torture, and the principle of non-refoulement. Art. 103 of the United Nations Charter is another key aspect of limits to state consent in international law. This article provides that in the event of a conflict between the obligations of a state under the Charter and its obligations under another international agreement, the obligations under the Charter shall take precedence.


This section introduces Siobhán Airey's work on 'sexing' consent and thus provides an example of how international law can be informed by feminist theories beyond questions that directly involve gender.

Further Readings

  • Source I
  • Source II


  • Summary I
  • Summary II

Table of Contents


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Part I - History, Theory, and Methods

Part II - General International Law

Part III - Specialized Fields


  1. PCIJ Lotus (France v Turkey) Rep Series A No 10, 18.
  2. Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (Reissue with a new Epilogue, CUP 2006) 65.
  3. Hedley Bull, The Anarchical Society (3rd edn Palgrave Macmillan 2002) 44; Kenneth Waltz, Theory of International Politics (1979) 88, 102; Helen Milner, 'The Assumption of Anarchy in International Relations Theory: A Critique' (1991) 17 (1) Review of International Studies 67-85, 70-74.
  4. Stephen C. Neff, ‘Consent’ in Concepts for International Law, at 128-129
  5. Stephen C. Neff, ‘Consent’ in Concepts for International Law, at 130-131.
  6. Antony Anghie, Imperialism, Sovereignty and the Making of International Law (CUP 2005) 34; James Anaya, Indigenous Peoples in International Law (2000) 19 et seq.
  7. | Mieke van der Linden, The Acquisition of Africa (1870-1914): The Nature of International Law (Brill Nijhoff 2017); James Anaya, Indigenous Peoples in International Law (2000) 17.
  8. UN Office of the High Commissioner for Human Rights, 'Free, Prior and Informed Consent', September 2013.
  9. Cf. Prosper Weil, Towards Relative Normativity in International Law?, 77 AJIL 413 (1983); Karen Knop, Introduction to the Symposium on Prosper Weil, "Towards Relative Normativity in International Law?" 114 AJIL Unbound 67 (2020).