When Can a Unilateral Act by a State Create Legal Obligations or Rights in International Law?

Japanese Attorney at Law - Bengoshi L.L.

• 7 min read

International law is predominantly formed through the consent of states, most commonly expressed via treaties or evolving through customary state practice. However, states can also create legal effects—binding obligations for themselves or new legal situations opposable to others—through their own unilateral acts or declarations. These acts, performed by a single state without the need for acceptance or reaction from other states, are a significant, albeit sometimes complex, feature of the international legal landscape. This article explores the conditions under which such unilateral acts can generate international legal rights and obligations.

The Foundation: Intent to Be Bound and Good Faith

The cornerstone for a unilateral act of a state to produce legal effects is the clear intention of that state to be legally bound by its declaration or conduct. This principle was famously articulated by the International Court of Justice (ICJ) in the Nuclear Tests Cases (Australia v. France; New Zealand v. France) (Judgments of December 20, 1974). France had made public statements, including by its President, indicating its intention to cease atmospheric nuclear testing after a certain series of tests. The ICJ found that:

"It is well recognized that declarations made by way of unilateral acts, concerning legal or factual situations, may have the effect of creating legal obligations... When it is the intention of the State making the declaration that it should become bound according to its terms, that intention confers on the declaration the character of a legal undertaking, the State being thenceforth legally required to follow a course of conduct consistent with the declaration."

The Court emphasized that no formal acceptance by other states is necessary for such a declaration to be binding, nor is any quid pro quo. The binding character rests on the principle of good faith, as interested states are entitled to require that the obligation be respected.

However, not every unilateral statement by a state official creates a legal obligation. The ICJ in the Frontier Dispute (Burkina Faso/Republic of Mali) case (Judgment of December 22, 1986) considered a statement made by Mali's Head of State at a press conference regarding a boundary mediation. The Court concluded that, in that specific context, the statement did not demonstrate an intention to be bound by a unilateral legal undertaking, emphasizing that "everything depends on the intention of the State in question."

The International Law Commission (ILC), in its "Guiding Principles applicable to unilateral declarations of States capable of creating legal obligations" (2006), has further clarified these aspects. These Principles, while not a binding treaty, provide authoritative guidance. They reiterate that a declaration creates legal obligations only if the state has the intention to be bound (Principle 1) and that such intention is to be ascertained by interpreting the content of the declaration, the factual circumstances of its making, and the reactions to it (Principle 3).

Unilateral acts can take various forms, each with distinct legal implications:

A. Promise (Unilateral Assumption of Obligations)

This is the category most clearly addressed in the Nuclear Tests Cases. A state, through a public declaration made by an authority vested with the power to bind the state (e.g., Head of State, Head of Government, Minister for Foreign Affairs – ILC Guiding Principle 4), can unilaterally undertake legally binding obligations.

  • Publicity: The declaration must generally be made publicly, though the form (written or oral) is not decisive (ILC Guiding Principle 5).
  • Clarity and Specificity: The terms of the promise must be clear and specific to indicate an intention to be bound. Vague or purely political statements are insufficient.
  • Irrevocability: Once a binding unilateral promise is made and relied upon by other states in good faith, it cannot be arbitrarily revoked or modified (ILC Guiding Principle 10). Modification or revocation generally requires consideration of the extent of reliance by other states and any fundamental change of circumstances.

B. Recognition

Recognition is a unilateral act by which a state acknowledges the existence of a certain factual situation or legal status and accepts the legal consequences that flow from it. Common examples include:

  • Recognition of States: Acknowledging that an entity meets the criteria of statehood.
  • Recognition of Governments: Accepting a new government as the legitimate representative of an existing state (particularly relevant after unconstitutional changes of government).
  • Recognition of Territorial Claims or Boundaries.
  • Recognition of Belligerency or Insurgency.

The legal effect of recognition is often to create an estoppel, meaning the recognizing state is precluded from later denying the situation it has recognized, especially if other states have relied on that recognition.

C. Protest

A protest is a formal objection by a state to a situation, claim, or conduct of another state which it considers to be contrary to international law or its own rights. The primary legal function of a protest is to:

  • Preserve the protesting state's legal rights and claims.
  • Prevent the legitimization or consolidation of the objected-to situation through acquiescence or prescription.
  • Signal that the protesting state does not accept the legality of the conduct or situation.

To be effective, a protest must generally be timely, clear, and consistently maintained. Failure to protest in circumstances where a protest would be expected can sometimes be interpreted as acquiescence.

D. Waiver or Renunciation

A waiver (or renunciation) is a unilateral act by which a state intentionally abandons or surrenders a right, claim, or legal position.

  • Clear Intent: Waiver must be clear and unequivocal. It is generally not presumed.
  • Example: The Permanent Court of International Justice (PCIJ) in the Legal Status of Eastern Greenland (Denmark v. Norway) case (Judgment of April 5, 1933) considered a declaration made by the Norwegian Foreign Minister (the "Ihlen Declaration") regarding Denmark's claim to sovereignty over Greenland. While the Court ultimately found that this declaration (stating Norway would not make difficulties concerning the Danish claim) was binding, it was interpreted in the context of bilateral negotiations and understandings rather than a purely unilateral renunciation of a potential Norwegian claim. A clearer example would be an explicit statement by a state that it no longer pursues a particular territorial claim.

States frequently make unilateral declarations or engage in conduct aimed at establishing or defining their rights, powers, or a particular legal situation. Examples include:

  • Declarations establishing the breadth of the territorial sea or exclusive economic zone (EEZ).
  • Laws granting nationality.
  • Assertions of sovereignty over newly discovered territory (terra nullius), although this is now largely historical.

The international legal effect of such assertions depends on their conformity with existing rules of international law:

  • If the assertion is made pursuant to a permissive rule of international law (e.g., a coastal state declaring an EEZ up to 200 nautical miles as permitted by UNCLOS), it is generally opposable to other states.
  • If the assertion goes beyond what is permitted by existing international law, or if the law is unsettled, its opposability to other states will depend on their reaction – i.e., their recognition or acquiescence.
    • The ICJ in the Fisheries Case (United Kingdom v. Norway) (Judgment of December 18, 1951) found that Norway's method of drawing straight baselines for its territorial sea, even if it departed from what the UK considered the general rule, had become opposable to the UK and other states due to their prolonged toleration and lack of consistent protest. This illustrates how unilateral assertions, coupled with the acquiescence of other affected states, can contribute to the evolution of customary international law or the establishment of a specific legal situation.

Formalities and Interpretation of Unilateral Acts

  • Form: As noted in the Nuclear Tests Cases and affirmed by the ILC (Guiding Principle 5), unilateral acts capable of creating legal obligations can be made orally or in writing. The form is not decisive, but the act must be public or at least known to the state(s) to whom it is addressed.
  • Interpretation: The interpretation of unilateral declarations is guided by the need to ascertain the state's intention to be bound. According to the ILC Guiding Principles (Principle 7):
    • The terms of the declaration should be interpreted in good faith, considering the text itself, the context in which it was made, and the circumstances of its making.
    • When a declaration is ambiguous, it should be interpreted restrictively, particularly if it purports to limit the sovereignty or freedom of action of the declaring state. This reflects the general principle that limitations on state sovereignty are not to be presumed.
    • Regard may be had to subsequent practice of the declaring state and the reactions of other states.

Invalidity, Modification, and Termination of Unilateral Acts

While a state can bind itself unilaterally, it is not an entirely unfettered power. The ILC Guiding Principles suggest that grounds for invalidity, termination, and suspension analogous to those applicable to treaties under the VCLT may apply to unilateral declarations.

  • Invalidity: A unilateral declaration may be invalid if (ILC Guiding Principle 8):
    • It conflicts with a peremptory norm of general international law (jus cogens). For instance, a unilateral promise to commit an act of aggression would be void. The PDF mentions that binding UN Security Council resolutions conflicting with jus cogens are also considered void, by analogy.
    • The consent to be bound was vitiated by error, fraud, corruption, or coercion against the state representative, or coercion of the state itself, similar to the grounds for invalidating treaties under the VCLT.
  • Modification and Revocation: A unilateral declaration that has created legal obligations for the declaring State cannot be revoked or modified arbitrarily (ILC Guiding Principle 10). In determining whether a revocation would be arbitrary, particular consideration should be given to:
    • Any specific terms of the declaration relating to revocation or modification.
    • The extent to which other states to whom the obligations are owed have relied on such obligations.
    • The extent to which there has been a fundamental change of circumstances (rebus sic stantibus).

Unilateral Acts of International Organizations

It is also important to note that international organizations can perform unilateral acts that produce legal effects. Binding decisions of the UN Security Council under Chapter VII of the UN Charter, for example, create legal obligations for UN member states (UN Charter Article 25). Regulations adopted by specialized agencies like the World Health Organization, or legislative acts within regional integration frameworks like the European Union (e.g., EU Regulations under Article 288 TFEU), are other instances of unilateral acts by international organizations creating binding rules for their member states or even individuals and corporations. The legal basis for these acts lies in the constituent treaty of the organization. Their interpretation often involves considering the organization's specific mandate and objectives, as highlighted by the ICJ in cases like the Advisory Opinion on Interpretation of the Agreement of 25 March 1951 between the WHO and Egypt (Judgment of December 20, 1980).

Conclusion

Unilateral acts and declarations represent a flexible and often direct means by which states can assume legal obligations, assert rights, or otherwise influence their legal relationships within the international community. While not as formally structured as treaty-making, their legal significance hinges on the clear intention of the acting state to create legal effects, interpreted in good faith and with due regard to the legitimate expectations of other states. The principles governing their formation, interpretation, and consequences, as increasingly clarified by international jurisprudence and the work of the ILC, underscore the dynamic nature of international law-making and the importance of carefully considering all forms of state conduct on the international stage.