ICJ Statute: Composition, Jurisdiction, and Advisory Opinions

The Statute of the International Court of Justice is the founding legal document that governs the UN’s principal judicial organ. Adopted in 1945 as an integral part of the UN Charter, the ICJ Statute replaced the earlier Statute of the Permanent Court of International Justice, which had operated under the League of Nations from 1922 until the League’s dissolution in 1946.¹ It sets out how the court is organized, which disputes it can hear, where it draws its law from, and how proceedings run from filing to final judgment. All 193 UN member states are automatically parties to it, and non-member states can join under conditions set by the General Assembly on the Security Council’s recommendation.²

How the Court Is Composed

Articles 2 through 33 set up a bench of fifteen judges. No two may be nationals of the same country, and the selection process is designed so that the world’s principal legal systems and major civilizations are represented. Judges serve nine-year terms and are elected through independent, simultaneous votes in the General Assembly and the Security Council. A candidate must win a majority in each body to secure a seat. Terms are staggered so that five seats come up for election every three years, which prevents a wholesale turnover of the bench at any one time.³

Once elected, judges are expected to be fully independent. They cannot hold political or administrative office, pursue any other occupation, or act as agent or counsel in any case. The court elects its own President and Vice-President, each serving three-year terms, and appoints a Registrar who handles administrative work, correspondence, and archives.

Judges Ad Hoc

Article 31 creates a distinctive feature of ICJ proceedings. If one party to a dispute already has a national sitting on the bench, the other party may appoint a person of its choosing to sit as a judge for that case only. If neither party has a national on the bench, both sides may each appoint one. Ad hoc judges participate on terms of complete equality with the elected members and are held to the same independence standards.³

Chambers

The full fifteen-judge bench hears most cases, but Article 26 allows the court to form smaller chambers of three or more judges to handle particular categories of disputes or individual cases. Parties must request a chamber, and the court sets its size with their approval.³ The option has been used sparingly, but it offers a faster alternative when both sides prefer it.

When the Court Has Jurisdiction

Article 34 limits parties in contentious cases to states. Individuals, corporations, and international organizations cannot file or be named as respondents.³ Even when a dispute ultimately affects millions of people, the case at The Hague is formally between governments.

Consent is the bedrock of ICJ jurisdiction. A state cannot be brought before the court against its will. Consent reaches the court through three main channels:

Special agreement. Two or more states jointly refer a specific dispute to the court, agreeing in advance to accept the outcome.
Treaty clause. Many treaties include clauses directing disputes about interpretation or application to the ICJ. A state that ratifies such a treaty has pre-consented to ICJ jurisdiction for those disputes.
Optional clause declaration. Under Article 36(2), states may file a standing declaration recognizing the court’s compulsory jurisdiction over legal disputes concerning treaty interpretation, questions of international law, breaches of international obligations, and the reparations owed for those breaches. Declarations can be unconditional, limited to certain states, or valid only for a fixed period.³

As of 2026, 75 of the 193 UN member states have deposited declarations accepting compulsory jurisdiction.⁴ Several major powers, including the United States, Russia, and China, have either never filed such a declaration or withdrawn one previously made. The court’s compulsory jurisdiction is therefore far from universal.

A fourth, less common path is forum prorogatum. If one state files a case against another that has not accepted jurisdiction, the respondent can choose to accept it after the fact by participating in the proceedings. Jurisdiction takes effect as of the date of acceptance.⁵ Most respondents decline, but the mechanism remains available.

When a respondent challenges the court’s authority, Article 36(6) gives the court itself the power to decide whether jurisdiction exists. This principle, sometimes called compétence de la compétence, prevents a state from shutting down proceedings by objection alone. Only if valid consent is found does the case proceed to the merits.³

What Law the Court Applies

Article 38 tells the court what law to use when deciding a dispute. It lists four categories in a clear hierarchy:

International treaties. Agreements between states that create binding rules expressly recognized by the parties. When a relevant treaty exists, it is the court’s starting point.
International custom. A general practice among states accepted as legally required. Proving customary law typically means showing both widespread, consistent state behavior and a shared belief that the behavior is obligatory.
General principles of law. Foundational concepts found across the world’s legal systems, such as good faith, the right to be heard, and the prohibition on unjust enrichment. These fill gaps where no treaty or custom directly applies.
Judicial decisions and scholarly writings. Subsidiary tools rather than independent sources. Court rulings and the work of leading legal scholars help interpret and clarify the three primary sources but do not create binding rules on their own.

Article 38 is widely regarded as the most authoritative statement of what counts as international law, and its influence extends well beyond ICJ proceedings.³

Article 59 adds an important limit: the court’s decisions have no binding force except between the parties and only in respect of that particular case.³ There is no formal doctrine of binding precedent. In practice, though, the court regularly cites its own earlier decisions, and states treat past judgments as highly persuasive.

How a Case Moves Through the Court

Articles 39 through 64 lay out the procedure. A case begins when a state files an application naming the dispute and the respondent, or when both states submit a special agreement. The process then splits into two phases.

In the written phase, each side files detailed briefs called memorials and counter-memorials, setting out facts, legal arguments, and evidence. The court may authorize further written submissions. Everything is submitted in English or French, the court’s two official languages. The oral phase follows, with public hearings where legal teams present arguments to the judges. Witnesses and expert witnesses may be called. After the hearings close, the judges deliberate in private and deliver their judgment in open court, in writing, with full reasoning.³

Provisional Measures

Under Article 41, the court can order provisional measures at any stage if it believes a party’s rights are at risk of irreparable harm before final judgment. These function much like preliminary injunctions in domestic courts. Article 41 uses the word “indicate” rather than “order,” which for decades left scholars arguing over whether these measures were merely recommendations or legally binding.³

The court settled that question in the 2001 LaGrand case (Germany v. United States), holding that provisional measures do create binding legal obligations. The court found that its earlier order “was not a mere exhortation” but “created a legal obligation for the United States.”⁶ Provisional measures are now among the court’s most visible tools, especially in cases involving armed conflict or humanitarian crises.

Judgments, Dissents, and Revision

Under Article 60, judgments are final and cannot be appealed. A party that disagrees has no higher court to turn to. Two narrow openings exist. A party may ask the court to clarify the meaning of a judgment, and under Article 61, a party may apply for revision if it discovers a decisive new fact that was unknown at the time of judgment and whose ignorance was not due to negligence. The revision application must be filed within six months of discovering the new fact and cannot be made more than ten years after the judgment.³

Article 57 guarantees that any judge who disagrees with all or part of a judgment may deliver a separate opinion.³ In practice, ICJ judgments almost always come with separate and dissenting opinions, sometimes longer and more detailed than the majority reasoning. These opinions carry no legal force but often shape how international law develops over time.

Advisory Opinions

Besides deciding disputes between states, the court issues advisory opinions on legal questions referred to it by authorized UN bodies. Articles 65 through 68 govern the process. The General Assembly and the Security Council can request an opinion on any legal question. Other UN organs and specialized agencies may do so on questions arising within the scope of their activities, and only if the General Assembly has authorized them.² Authorized requesters include the Economic and Social Council, the Trusteeship Council, and sixteen specialized agencies.⁷

Advisory opinions are technically non-binding. No state is a “party” in the formal sense, and the goal is legal clarification rather than dispute resolution. In practice they carry significant weight, and advisory opinions on topics such as nuclear weapons and the obligations of occupying powers have shaped international law alongside the court’s binding judgments.

How Judgments Get Enforced

This is where the system hits its most obvious structural limit. Judgments bind the parties, but the court has no police force and no power to compel compliance on its own. Enforcement runs through Article 94 of the UN Charter. Under paragraph 1, every UN member undertakes to comply with the court’s decisions in cases to which it is a party. Under paragraph 2, if a state fails to do so, the other party may bring the matter to the Security Council, which can make recommendations or decide upon measures to give effect to the judgment.²

The catch sits in the phrase “if it deems necessary.” The Security Council has discretion over whether to act, and any of its five permanent members can veto enforcement. In the best-known test of this mechanism, Nicaragua asked the Security Council to enforce the court’s 1986 judgment against the United States. The United States vetoed the resolution. Compliance in the ICJ system is often a matter of diplomatic pressure and reputational cost rather than coerced obedience. Most judgments are ultimately complied with, but the enforcement gap remains the single biggest criticism of the court’s design, and it is why questions of jurisdiction and consent carry such weight at the front end of every case.

1
International Court of Justice. Permanent Court of International Justice
2
United Nations. UN Charter – Chapter XIV: The International Court of Justice
3
International Court of Justice. Statute of the International Court of Justice
4
International Court of Justice. Declarations Recognizing the Jurisdiction of the Court as Compulsory
5
International Court of Justice. Basis of the Court’s Jurisdiction
6
International Court of Justice. LaGrand (Germany v. United States of America)
7
International Court of Justice. Organs and Agencies Authorized to Request Advisory Opinions