Breach of an International Obligation

Meaning of Breach of an International Obligation

Under the law of State responsibility, a State incurs international responsibility when its conduct is attributable to it and that conduct constitutes a breach of an international obligation.

The basic rule is reflected in Article 2 of the International Law Commission’s Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA).

An internationally wrongful act exists when:

• the conduct is attributable to the State under international law, and
• the conduct constitutes a breach of an international obligation binding upon that State.

Thus, attribution alone is not sufficient. There must also be a violation of an obligation.

Simple formula:

State responsibility = Attribution + Breach of an international obligation

What is an International Obligation?

An international obligation is a legal duty imposed upon a State by international law.

The obligation may arise from:

• a treaty
• customary international law
• a general principle of law
• certain binding decisions or rules recognised under international law
• other applicable sources of international legal obligations

For example:

• A treaty may require a State to protect diplomatic premises.
• Customary international law may prohibit certain forms of treatment of foreign nationals.
• International law may require a State to respect another State’s territorial sovereignty.

When the State fails to perform such an obligation, there may be a breach.

Article 12 of ARSIWA

Article 12 ARSIWA provides the central rule for determining breach:

There is a breach of an international obligation by a State when an act of that State is not in conformity with what is required of it by that obligation, regardless of its origin or character.

The important point is that the conduct must be compared with the actual legal requirement imposed upon the State.

Example

Suppose State A has undertaken under a treaty to notify State B before carrying out a particular activity.

If State A carries out the activity without the required notification, its conduct is not in conformity with the obligation.

Therefore, there may be a breach of the international obligation.

Essential Elements of a Breach

The determination of breach generally involves examining several questions.

Existence of an International Obligation

First, there must be an international obligation binding upon the State.

There cannot be a breach of an obligation that does not legally bind the State.

Conduct of the State

There must be some conduct attributable to the State.

The conduct may take the form of:

• an act, or
• an omission.

A State can therefore breach an obligation either by doing something prohibited or by failing to do something required.

Non-Conformity with the Obligation

The conduct must be inconsistent with what the international obligation requires.

The test is essentially:

What did international law require the State to do?

and

What did the State actually do or fail to do?

If the two are inconsistent, a breach may exist.

Attribution

The conduct must be attributable to the State under the rules of international law.

This is governed principally by Articles 4–11 ARSIWA.

For example, conduct of:

• State organs,
• entities exercising governmental authority,
• persons acting under State instructions, direction or control in appropriate circumstances,

may be attributable to the State under the relevant rules.

Breach May Result from an Act or Omission

International obligations can require either positive action or restraint.

Breach by Commission

A State breaches an obligation by doing something that international law prohibits.

For example, if international law prohibits a particular intervention in another State’s affairs, carrying out that intervention may constitute a breach.

Breach by Omission

A State may also breach an obligation by failing to act when international law requires action.

For example, if a State has an international obligation to protect certain persons or property and deliberately fails to take the required measures, the omission may constitute a breach.

Therefore:

Breach = prohibited act OR failure to perform a required act

Article 13: Obligation Must Be Binding at the Time of Conduct

Article 13 ARSIWA establishes an important temporal rule.

A State’s conduct cannot constitute a breach unless the obligation was binding upon that State at the time when the conduct occurred.

This prevents a State from being held responsible for violating an obligation that did not yet legally bind it.

Example

If a treaty entered into force for State A on 1 January 2025, conduct occurring on 1 December 2024 generally cannot be treated as a breach of that treaty obligation merely because the treaty later became binding.

Temporal Application of Breach

The timing of the breach is particularly important because international obligations may operate differently over time.

ARSIWA distinguishes between different forms of breach.

Instantaneous Breach

An obligation may be breached through conduct occurring at a particular point in time.

For example, where a State performs a prohibited act at a particular moment, the breach may be instantaneous.

Continuing Breach

Under Article 14 ARSIWA, a breach is continuing when the obligation requires the State to prevent or cease a particular situation and the State’s conduct continues over time.

In such cases, the breach begins when the conduct starts and continues for as long as the conduct remains contrary to the obligation.

Example:

If a State unlawfully maintains a situation that it is under an international obligation to terminate, the breach may continue for the entire period during which the unlawful situation persists.

Composite Breach

Article 15 ARSIWA deals with breaches consisting of a series of actions or omissions defined collectively as wrongful.

A breach may therefore arise not from one isolated act but from a series of acts or omissions that, taken together, amount to the wrongful conduct identified by the obligation.

This is particularly relevant where an obligation concerns a pattern of conduct rather than a single event.

Article 14 and the Duration of Breach

Article 14 is important for understanding the consequences of continuing violations.

The duration of the breach may affect:

• when responsibility arises,
• the period for which the wrongful conduct continues,
• the obligation to cease the conduct,
• reparation for injury caused during the period of breach.

A continuing breach is not treated as though the wrongful conduct occurred only on its first day.

Article 15 and Composite Acts

A composite breach occurs when a State’s responsibility results from a series of acts or omissions.

The breach occurs when the conduct reaches the point at which the elements required for the wrongful act are satisfied.

Article 15 is particularly significant in relation to obligations concerning:

• systematic discrimination,
• repeated violations,
• patterns of conduct,
• cumulative wrongful behaviour.

Source of the Obligation Does Not Matter for Article 12

Article 12 deliberately uses the phrase “regardless of its origin or character.”

This means that for the purpose of determining whether a breach exists, the obligation may derive from different sources of international law.

The important question is whether the State’s conduct is inconsistent with an obligation that legally binds it.

Thus, a breach may involve an obligation arising from:

Source	Possible obligation
Treaty	Obligation expressly undertaken by the State
Customary international law	Rule accepted as legally binding through customary practice
General principles	Applicable general principle of international law
Other applicable international rules	Obligations arising under the relevant international legal framework

Primary Rules and Secondary Rules

A useful distinction in State responsibility is between primary rules and secondary rules.

Primary Rules

Primary rules establish the substantive obligations of States.

For example:

• a treaty obligation,
• prohibition of aggression,
• obligation to respect diplomatic immunity,
• obligation to protect certain persons.

These rules tell States what they must or must not do.

Secondary Rules

Secondary rules determine the legal consequences of violating a primary obligation.

ARSIWA is principally concerned with these secondary rules.

It addresses questions such as:

• When is conduct attributable to a State?
• When does a breach occur?
• What are the consequences of responsibility?
• What constitutes reparation?
• When may countermeasures be taken?

Easy distinction:

Primary rule → What must the State do?

Secondary rule → What happens when the State violates that obligation?

Breach and Fault

As a general matter, State responsibility under ARSIWA does not depend upon a general requirement of fault.

The relevant primary obligation may, however, itself contain a requirement concerning:

• intent,
• knowledge,
• negligence,
• recklessness,
• or another mental element.

Therefore, whether fault is relevant depends upon the particular international obligation being breached.

The secondary law of State responsibility should not be confused with the substantive requirements of the primary rule.

Breach and Circumstances Precluding Wrongfulness

Even where conduct appears inconsistent with an international obligation, the conduct may, in certain circumstances, not be considered wrongful because of a recognised circumstance precluding wrongfulness.

ARSIWA deals with these in Articles 20–27.

They include:

• Consent — Article 20
• Self-defence — Article 21
• Countermeasures — Article 22
• Force majeure — Article 23
• Distress — Article 24
• Necessity — Article 25
• Compliance with peremptory norms — Article 26
• Consequences of invoking these circumstances — Article 27

These provisions are important because the existence of conduct inconsistent with an obligation must be assessed together with the applicable rules governing wrongfulness.

Breach vs Attribution

These concepts must not be confused.

Attribution	Breach
Asks whether the conduct is legally connected to the State	Asks whether the conduct violates an international obligation
Mainly addressed in Articles 4–11 ARSIWA	Mainly addressed in Articles 12–15 ARSIWA
Focuses on who acted	Focuses on whether the obligation was violated
Example: conduct of a State organ	Example: conduct contrary to a treaty obligation

Both are generally required for an internationally wrongful act under Article 2.

Breach vs Injury

A breach and injury are also different concepts.

A State may breach an international obligation even where the legal consequences do not depend upon proof of material damage.

Conversely, the question of injury becomes particularly important when determining reparation.

The central question under Article 12 is whether the State’s conduct is not in conformity with its international obligation.

Breach and Reparation

Once an internationally wrongful act is established, the responsible State is subject to the consequences of responsibility.

Under Article 30 ARSIWA, the responsible State is under obligations concerning:

• cessation of the wrongful act, where the breach is continuing; and
• appropriate assurances and guarantees of non-repetition, where circumstances require.

Under Article 31, the responsible State must make full reparation for the injury caused by the internationally wrongful act.

Forms of reparation include:

• Restitution — Article 35
• Compensation — Article 36
• Satisfaction — Article 37

The classic principle comes from the Factory at Chorzów (1928) case, where the Permanent Court of International Justice emphasised the principle of full reparation for injury caused by an internationally wrongful act.

Important Cases

Factory at Chorzów (Germany v Poland)

The case is a foundational authority on the consequences of internationally wrongful conduct.

The Permanent Court of International Justice established the principle that reparation should, as far as possible, wipe out the consequences of the illegal act and restore the situation that would probably have existed had the wrongful act not occurred.

Exam relevance:
Important for understanding the relationship between breach, responsibility and reparation.

United States Diplomatic and Consular Staff in Tehran (United States v Iran)

The ICJ examined Iran’s responsibility for violations involving the United States diplomatic and consular premises and personnel.

The case demonstrates how failures to comply with international obligations can give rise to State responsibility.

Exam relevance:
Useful for connecting breach of international obligations with State responsibility.

Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States)

The ICJ examined violations of international obligations concerning, among other matters, the use of force and non-intervention.

The case is particularly important for demonstrating that obligations may arise from customary international law as well as treaties.

Exam relevance:
Useful when discussing the source of international obligations and breach of customary rules.

Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro)

The ICJ considered Serbia’s obligations under the Genocide Convention, including the obligation to prevent genocide.

The case illustrates that a State’s international responsibility may arise from failure to perform a positive obligation, not merely from directly committing the prohibited act.

Exam relevance:
Important for understanding breach by omission.

Simple Flowchart

International obligation exists

↓

Obligation is binding upon the State

↓

State engages in conduct

↓

Conduct is attributable to the State

↓

Conduct is not in conformity with the obligation

↓

Breach of international obligation

↓

Internationally wrongful act

↓

State responsibility

↓

Cessation + Reparation + Other applicable consequences

Quick Revision

Point	Rule
Basic provision	Article 12 ARSIWA
Meaning	Conduct is not in conformity with an international obligation
Obligation must bind State	Article 13
Act or omission	Both may constitute breach
Instantaneous breach	Breach occurring at a particular point
Continuing breach	Article 14
Composite breach	Article 15
Attribution	Articles 4–11
Circumstances precluding wrongfulness	Articles 20–27
Cessation	Article 30
Full reparation	Article 31
Restitution	Article 35
Compensation	Article 36
Satisfaction	Article 37
Leading reparation case	Factory at Chorzów

Key Exam Points

• Article 12 ARSIWA provides the basic definition of breach.
• A breach occurs when State conduct is not in conformity with an international obligation.
• The obligation may arise from a treaty, custom or another applicable source of international law.
• The obligation must be binding upon the State when the conduct occurs under Article 13.
• Breach may occur through an act or omission.
• Article 14 deals with continuing breaches.
• Article 15 deals with composite breaches.
• Attribution and breach are separate requirements under Article 2.
• Fault is not generally an independent requirement under the secondary rules of State responsibility, although the primary obligation may require a particular mental element.
• A breach may lead to cessation and reparation.
• Factory at Chorzów is a leading authority on full reparation.

Conclusion

Breach of an international obligation is one of the central components of State responsibility. Under Article 12 of ARSIWA, the essential question is whether the conduct of the State is not in conformity with an international obligation binding upon it. The breach may arise through an act or omission and may be instantaneous, continuing or composite depending upon the nature of the obligation.

For examination purposes, the most important framework is:

Article 2 → Attribution + Breach

Articles 12–15 → Nature and timing of breach

Articles 20–27 → Circumstances precluding wrongfulness

Articles 30–37 → Consequences and reparation

Factory at Chorzów → Full reparation