The International Court of Justice — Public International Law Notes

The International Court of Justice

The very first case the new World Court decided, the Corfu Channel Case (1949), arose when British warships passing through an Albanian strait struck mines and lost forty-four sailors. Albania was held responsible. But notice what had to happen first: both States had to agree to let the Court hear them. That is the single most important thing about the ICJ — it is a court without compulsory power over sovereign States. It can decide only what States consent to give it. Grasp “jurisdiction rests on consent” and you have grasped the topic.

What the ICJ is, its composition, jurisdiction and the law it applies

The International Court of Justice (ICJ) is the principal judicial organ of the United Nations (Art. 92 of the Charter). It sits at the Peace Palace in The Hague and works under its own Statute (the ICJ Statute, annexed to and forming part of the Charter, 1945), the successor to the Permanent Court of International Justice of the League era. Take it in four parts: composition, contentious jurisdiction, advisory jurisdiction, and the law it applies.

A. Composition (Statute, Articles 2–33)

Fifteen judges, no two of whom may be nationals of the same State (Art. 3), chosen for their high moral character and qualifications for the highest judicial offices, so as to represent the main forms of civilisation and the principal legal systems of the world (Art. 9).
They are elected for nine years (one-third every three years) and are re-eligible, elected by the General Assembly and the Security Council voting separately (Arts. 4, 8) — an absolute majority in both is needed.
Quorum is nine judges (Art. 25).
Ad hoc judge (Art. 31) — a party to a case that has no judge of its nationality on the bench may appoint a judge ad hoc for that case, so that both sides are represented.

Only States may be parties in contentious cases (Art. 34(1)) — individuals and organisations cannot litigate before the ICJ.
Jurisdiction is founded on the parties’ consent, given in one of three ways (Art. 36):
- by special agreement (compromis) — the parties jointly submit an existing dispute;
- by a treaty clause (a compromissory clause) referring future disputes under that treaty to the Court; or
- by the optional clause (Art. 36(2)) — a State’s declaration in advance accepting the Court’s jurisdiction as compulsory in relation to any other State accepting the same obligation. This is the so-called “compulsory jurisdiction” — compulsory only between States that have both made the declaration, and often subject to reservations.

C. Advisory jurisdiction (Article 65)

The Court may give an advisory opinion on any legal question at the request of the General Assembly or the Security Council, or of other UN organs and specialised agencies authorised by the GA. An advisory opinion is, in principle, not binding — it is advice — though it carries great authority. (Many of the cases in this very unit — Reparation, Certain Expenses, Namibia — are advisory opinions.)

D. The law the Court applies (Article 38) and the force of judgment

The Court decides in accordance with Article 38(1) — international conventions (treaties), international custom, the general principles of law recognised by civilised nations, and, as subsidiary means, judicial decisions and the teachings of the most highly qualified publicists (loop back to Unit I, Sources).
A judgment is final and without appeal and binding only between the parties and in respect of that case (Arts. 59–60).
Enforcement is by the Security Council: if a party fails to comply, the other may have recourse to the Council, which may make recommendations or decide measures (Art. 94(2) of the Charter).

⚠️ DON’T CONFUSE — contentious jurisdiction vs advisory jurisdiction

Contentious jurisdiction is a lawsuit between two States: only States are parties (Art. 34), it needs their consent (special agreement, treaty clause, or the optional clause), and the judgment binds the parties (Arts. 59–60). Advisory jurisdiction is a legal opinion requested by a UN organ (GA, SC or an authorised body) under Art. 65: no State is a “party”, and the opinion does not bind anyone. So the two axes are who asks and who is bound: States litigating and bound (contentious) versus an organ enquiring and not bound (advisory). Do not say an advisory opinion “binds the States concerned”, and do not say a contentious judgment is “merely advisory” — they are opposite.

Article 36(2), ICJ Statute (1945) — the optional clause: “The states parties to the present Statute may at any time declare that they recognize as compulsory ipso facto and without special agreement, in relation to any other state accepting the same obligation, the jurisdiction of the Court in all legal disputes…”

Article 94(1), UN Charter (1945): “Each Member of the United Nations undertakes to comply with the decision of the International Court of Justice in any case to which it is a party.”

In Simple Terms: The ICJ is the UN’s court — fifteen judges from fifteen different countries, elected for nine years by the Assembly and the Council together, sitting at The Hague. Only States can sue there, and the Court can hear a case only if the States have agreed to let it — by a one-off agreement, a treaty clause, or an advance “optional clause” declaration (the nearest thing to compulsory jurisdiction). It can also give non-binding advisory opinions to UN organs. It decides by the sources in Article 38, its judgments are final, and the Security Council backs up enforcement (Art. 94(2)).

🧩 WORKED EXAMPLE — State A drags State B before the Court

Facts. State A files an application asking the ICJ to decide a boundary dispute with State B. B has never made any optional-clause declaration, is party to no treaty referring the matter to the Court, and refuses to sign any special agreement. B objects that the Court has no jurisdiction.

Rule. ICJ jurisdiction in contentious cases rests on the parties’ consent, expressed through a special agreement, a treaty clause, or matching optional-clause declarations (Art. 36). No consent, no jurisdiction.

Apply. The decoy is that A has genuinely been wronged and the Court is the “World Court”, so it must surely be able to hear the case. But none of the three consent routes exists as against B: B made no declaration, is bound by no compromissory clause, and will not agree. There is nothing on which jurisdiction can rest.

Conclusion. The Court must decline jurisdiction. A cannot force an unwilling B before the ICJ — the hallmark of a consent-based court.

flowchart TD
    A["International Court of Justice<br/>(principal judicial organ — Art. 92; Statute 1945)"]
    A --> B["Composition: 15 judges, 9 years,<br/>elected by GA + SC separately;<br/>ad hoc judge (Art. 31)"]
    A --> C["Contentious: only STATES (Art. 34);<br/>consent — special agreement / treaty clause /<br/>optional clause (Art. 36(2)); judgment BINDS"]
    A --> D["Advisory (Art. 65): opinion to GA/SC/<br/>authorised organs; NOT binding"]
    A --> E["Law applied: Art. 38 (treaties, custom,<br/>general principles, decisions & writings)"]
    A --> F["Enforcement by Security Council (Art. 94(2))"]
    classDef box fill:#e8f0fe,stroke:#333,color:#111;
    class A,B,C,D,E,F box;

Case Laws

Corfu Channel Case (UK v. Albania, 1949, ICJ) — the Court’s first contentious judgment; a State is responsible for damage caused by its knowledge of a hazard in its waters; illustrates consent-based jurisdiction.
Nicaragua v. United States (1986, ICJ) — jurisdiction founded on the optional clause (Art. 36(2)); a State that has accepted compulsory jurisdiction cannot escape a merits decision by boycotting the proceedings.
Legality of the Threat or Use of Nuclear Weapons (1996, ICJ, Advisory Opinion) — a leading exercise of the advisory jurisdiction (Art. 65); the opinion is authoritative but not binding.

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The International Court of Justice — Public International Law Notes