Intervention before the ICJ

Introduction

Intervention before the International Court of Justice (ICJ) is a procedure through which a State that is not originally a party to a case seeks to participate in the proceedings because it considers that it has a legal interest that may be affected by the Court’s decision.

Intervention is governed principally by Articles 62 and 63 of the Statute of the International Court of Justice.

The basic idea is:

Case before ICJ

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Third State has an interest or treaty-related concern

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State seeks intervention

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ICJ determines whether statutory requirements are satisfied

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State may participate to the extent permitted

Intervention does not make the intervening State an automatic full party to the original dispute.

Meaning of Intervention

Intervention allows a State that is not originally participating as a party to enter an existing ICJ case for a limited procedural purpose.

The rationale is that an ICJ judgment may have consequences for a third State’s legal interests or for the interpretation of a treaty to which that State is also a party.

The procedure therefore attempts to balance two interests:

• protecting the legal interests of third States; and
• preserving the principle that the ICJ cannot adjudicate a dispute involving a State without that State’s consent.

Legal Basis

The two principal provisions are:

Article 62 – Intervention to Protect a Legal Interest

Article 62 applies where a State considers that it has a legal interest of a nature that may be affected by the decision in the case.

The State must make an application to the Court for permission to intervene.

The Court decides whether to allow the intervention.

Article 63 – Intervention Concerning Treaty Interpretation

Article 63 applies where the construction of a convention to which States other than those involved in the case are parties is in question.

The Registrar notifies those States.

A State receiving such notification has the right to intervene in the proceedings concerning the construction of the convention.

Article 62 and Article 63 – Basic Difference

Article 62	Article 63
Protects a State’s legal interest	Concerns interpretation/construction of a treaty
State applies to intervene	Right to intervene arises upon notification
Court decides whether intervention is permitted	Intervention is available as of right, subject to statutory conditions
Court assesses whether legal interest may be affected	State must be party to the convention whose construction is in question
More discretionary	More treaty-based

This distinction is extremely important for examinations.

Intervention under Article 62

Article 62 contains three important elements:

Applicant must be a State

It must have a legal interest

That interest may be affected by the Court’s decision

The State must then submit an application for permission to intervene.

Legal Interest

The interest under Article 62 must be a legal interest, not merely:

• political interest;
• economic interest;
• diplomatic interest;
• general concern about the outcome.

The Court therefore looks for a genuine legal interest connected with the subject matter of the case.

Example

Suppose States A and B are disputing a territorial boundary.

State C claims that the boundary decision could affect a legal right it possesses concerning the same territory.

State C may seek intervention under Article 62.

But merely being politically interested in the outcome would not normally be sufficient.

“May Be Affected”

Article 62 does not require the State to prove that its legal interest will definitely be affected.

The requirement is that the interest may be affected by the decision.

This is assessed at the stage of the application for intervention.

The Court does not have to conclude that the interest will actually be affected with certainty.

Intervention Is Not an Independent Claim

A State intervening under Article 62 does not automatically obtain the right to introduce an entirely new dispute against the original parties.

Intervention is connected to the existing proceedings.

The Court therefore examines the scope and purpose of the intervention carefully.

Nicaragua Intervention Case

An important authority is:

Land, Island and Maritime Frontier Dispute (El Salvador/Honduras), Application by Nicaragua for Permission to Intervene

Nicaragua sought permission to intervene in the dispute between El Salvador and Honduras.

The ICJ examined the requirements of Article 62 and accepted that Nicaragua had a legal interest of a nature that might be affected by the decision.

The case is particularly important for understanding:

• legal interest;
• possible effect on that interest;
• Article 62;
• limited intervention.

Costa Rica Intervention

Another important development occurred in the Territorial and Maritime Dispute (Nicaragua v Colombia).

Costa Rica sought permission to intervene under Article 62.

The Court examined whether Costa Rica had a legal interest that might be affected by the decision.

The case demonstrates that a State can seek intervention even where it is not an original party to the dispute.

Honduras Intervention

In Territorial and Maritime Dispute (Nicaragua v Colombia), Honduras also sought intervention.

The Court’s jurisprudence in this area illustrates the importance of identifying a concrete legal interest rather than merely a general concern about the outcome.

Article 63 Intervention

Article 63 is fundamentally different.

It applies when the construction of a treaty is in question in a case.

If a State is also a party to that treaty, it has a right to intervene concerning the interpretation of the treaty.

Example

Suppose States A and B are litigating before the ICJ about the interpretation of a treaty.

States C and D are also parties to that treaty.

If the Court is required to interpret the treaty, C and D are notified.

They may intervene concerning the treaty’s construction.

Why Article 63 Exists

Article 63 protects the interests of other treaty parties.

A treaty interpretation adopted by the ICJ may have broader significance for the interpretation of the same treaty.

Article 63 therefore gives other parties to the convention an opportunity to present their views on its construction.

Article 63 Is About Treaty Construction

The key word is:

Construction

In this context, construction means the interpretation of the treaty.

Therefore, Article 63 intervention is not a general opportunity to participate in every aspect of the case.

Its scope is connected to the construction of the relevant convention.

Effect of Article 63 Intervention

Article 63 provides that where a State intervenes, the construction given by the judgment will be equally binding upon that State.

This is an important distinction from Article 62.

Under Article 63, intervention has a specific relationship with the interpretation of the treaty.

Article 62 vs Article 63 – Detailed Comparison

Feature	Article 62	Article 63
Purpose	Protect legal interest	Participate in treaty construction
Applicant	State	State party to the relevant convention
Legal interest required?	Yes	No separate Article 62-type legal-interest test
Court’s permission	Required	Intervention is a right if conditions are satisfied
Trigger	Legal interest may be affected	Construction of a convention is in question
Scope	Determined by Court	Limited to treaty construction
Effect on intervenor	Does not automatically become full party	Treaty construction in judgment is binding on intervenor
Main character	Protective	Treaty-interpretive

Intervention and State Consent

The ICJ’s jurisdiction is fundamentally based on State consent.

Intervention must therefore not be confused with forcing a third State into litigation.

The Court cannot use intervention as a way to adjudicate a separate dispute between the original parties and a third State without the necessary jurisdictional basis.

This is particularly important under Article 62.

Monetary Gold Principle

The Monetary Gold Removed from Rome in 1943 case established an important limitation on the Court’s jurisdiction.

The Court will not decide a case where determining the legal responsibility of an absent third State would constitute the very subject matter of the decision, unless that State has consented to the Court’s jurisdiction.

This principle protects the consent-based nature of ICJ jurisdiction.

Intervention Does Not Defeat the Monetary Gold Principle

Intervention cannot be used to circumvent the rule that the Court cannot decide the legal rights or responsibility of an absent State without its consent.

Therefore:

Intervention ≠ automatic jurisdiction over a third State

The Court must still respect the fundamental principle of State consent.

Intervention and Third States

A third State may intervene because the outcome could affect its legal position.

However, intervention does not necessarily transform the entire case into a dispute involving three parties.

The Court determines the scope and effect of the intervention according to the applicable Article of the Statute.

Procedure for Article 62 Intervention

A State seeking intervention under Article 62 generally follows this structure:

Existing ICJ case

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Third State identifies legal interest

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Legal interest may be affected by decision

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Application to intervene

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Original parties given opportunity to respond

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Court examines requirements

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Court decides whether to permit intervention

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If permitted → intervention within specified scope

Procedure for Article 63 Intervention

The process is different:

Existing ICJ case

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Construction of a convention is in question

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Other States parties to convention notified

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State may intervene

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Intervention concerning treaty construction

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Court considers treaty interpretation

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Construction in judgment has specified binding effect

Intervention Is Ancillary to Main Proceedings

Intervention is generally incidental or ancillary to the principal proceedings.

The original dispute remains the central case.

The intervention exists because of a specific legal relationship between the third State and the subject matter of the proceedings.

Intervention and Party Status

A very important examination point is that intervention does not necessarily make the intervening State a party to the case.

A State can intervene without becoming a full party in the same sense as the original litigants.

This distinction is particularly important when analysing Article 62.

Intervention as a Party vs Non-Party Intervention

The ICJ has recognised that intervention may occur in different procedural forms.

A State may seek intervention:

• to protect a legal interest; or
• in relation to treaty interpretation.

The precise consequences depend on the applicable statutory provision and the terms of the Court’s decision.

Intervention and Jurisdiction

Intervention does not independently create jurisdiction over the underlying dispute.

The Court must have jurisdiction over the original proceedings.

For Article 62, the intervening State’s participation does not automatically mean that the Court acquires jurisdiction to determine every dispute between that State and the original parties.

Intervention and Merits

The intervening State does not necessarily obtain an unrestricted opportunity to argue every issue in the merits.

The Court controls the scope of intervention.

The State may participate only to the extent permitted by the applicable intervention procedure.

Important Cases

Monetary Gold (Italy v France, United Kingdom and United States)

Key principle: The Court cannot determine the legal responsibility or rights of an absent third State where that State’s legal position is the very subject matter of the decision without its consent.

Nicaragua’s Intervention in El Salvador/Honduras

Key principle: Article 62 requires a legal interest of a nature that may be affected by the decision.

Territorial and Maritime Dispute (Nicaragua v Colombia) – Costa Rica

Important for understanding the requirements and limits of intervention under Article 62.

Territorial and Maritime Dispute (Nicaragua v Colombia) – Honduras

Further illustrates the Court’s approach to Article 62 intervention and the need for a legally protected interest.

Whaling in the Antarctic (Australia v Japan)

New Zealand’s intervention under Article 63 is an important modern example of treaty-based intervention.

New Zealand participated concerning the interpretation of the International Convention for the Regulation of Whaling.

This is an excellent case to remember for Article 63.

Intervention and the Whaling Case

The Whaling in the Antarctic proceedings provide a particularly clear example of Article 63.

New Zealand was not an original party to the dispute between Australia and Japan but was also a party to the relevant convention.

Because the construction of the convention was in question, New Zealand exercised its right to intervene under Article 63.

Exam Formula

Article 63

Treaty construction

Other treaty party

↓

Right to intervene

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Whaling in the Antarctic

Intervention vs Joinder

Intervention should not be confused with joinder.

Intervention

A third State seeks to participate in an existing case because of a legal interest or treaty-interpretation issue.

Joinder

Joinder involves bringing additional parties into proceedings in a manner that makes them parties to the dispute.

The precise procedural consequences depend on the applicable rules and circumstances.

Intervention vs Third-Party Participation

Intervention is a specific legal procedure governed by the ICJ Statute.

It should not be treated simply as informal participation by an interested State.

The intervening State must satisfy the applicable requirements of Article 62 or Article 63.

Intervention and Provisional Measures

Intervention and provisional measures are different procedures.

Provisional measures under Article 41 protect rights pending final judgment.

Intervention under Articles 62–63 allows certain third States to participate in existing proceedings.

They may arise in the same case, but they serve different purposes.

Important ICJ Statute Provisions

Provision	Subject
Article 34	Only States may be parties in contentious cases
Article 36	Jurisdiction
Article 41	Provisional measures
Article 59	Binding force of judgments
Article 62	Intervention to protect legal interest
Article 63	Intervention concerning treaty construction
Article 64	Expenses of proceedings

The most important provisions for this topic are Articles 62 and 63.

Exam-Oriented Distinction

Article 62

Think:

“My legal interest may be affected.”

Article 63

Think:

“This treaty to which I am a party is being interpreted.”

Easy Memory Trick

62 → Legal Interest

63 → Convention Construction

Complete Flowchart

ICJ Case

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Third State wants to participate

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Why?

↙︎　　　　　　　　　↘︎

Legal interest may be affected　　 Treaty construction

↓　　　　　　　　　　　　　　　　↓

Article 62　　　　　　　　　 Article 63

↓　　　　　　　　　　　　　　　　↓

Application for permission　　 Right to intervene

↓　　　　　　　　　　　　　　　　↓

Court examines requirements　　 Relevant treaty party notified

↓　　　　　　　　　　　　　　　　↓

Intervention if permitted　　　 Intervention on construction

Quick Revision

Question	Answer
Meaning	Participation of a third State in an existing ICJ case
Main provisions	Articles 62 & 63 ICJ Statute
Article 62	Legal interest may be affected
Article 63	Construction of a convention
Article 62 application	Required
Article 62 legal interest	Must be legal, not merely political
Article 63 treaty requirement	State must be a party to the convention
Article 62 permission	Court decides
Article 63 character	Right to intervene when conditions are satisfied
Full party automatically?	No
Key jurisdiction principle	State consent
Important limitation	Monetary Gold principle
Article 63 case	Whaling in the Antarctic
Article 62 cases	Nicaragua intervention; Costa Rica/Honduras interventions
Main distinction	Article 62 protects legal interest; Article 63 concerns treaty interpretation

Key Exam Points

• Intervention before the ICJ is governed primarily by Articles 62 and 63 of the ICJ Statute.
• Article 62 concerns a State’s legal interest of a nature that may be affected by the decision.
• Article 62 requires an application for permission to intervene.
• A legal interest must be distinguished from a merely political or economic interest.
• The intervening State does not automatically become a full party to the original dispute.
• Article 63 applies where the construction of a convention to which other States are parties is in question.
• A State party to that convention has a right to intervene concerning its construction.
• Article 62 is primarily protective; Article 63 is primarily treaty-interpretive.
• Intervention does not independently create jurisdiction over a third State.
• The Monetary Gold principle protects absent States from having their legal responsibility determined without consent.
• Whaling in the Antarctic is an important Article 63 example.
• Nicaragua’s intervention in El Salvador/Honduras is an important Article 62 authority.
• Intervention should be distinguished from joinder, provisional measures and ordinary party status.

Conclusion

Intervention before the ICJ is an important mechanism for protecting the interests of States that are not original parties to a dispute. It prevents the Court’s proceedings from completely ignoring the legal interests of third States while respecting the fundamental principle of State consent to international jurisdiction.

The two provisions must be clearly distinguished:

Article 62 → Legal Interest

A State may seek permission to intervene when it has a legal interest that may be affected by the Court’s decision.

Article 63 → Treaty Construction

A State that is party to a convention being interpreted in the case has a right to intervene concerning the construction of that convention.

For examinations, the most important authorities are Monetary Gold, the Nicaragua intervention proceedings, and Whaling in the Antarctic.