Legal Aptitude: International Law

Legal Aptitude: International Law

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

International Law is the body of rules governing relations between sovereign states and other entities with international legal personality (UN, ICRC, the Holy See). For LAT Legal Reasoning, focus on three pillars:

• Sources of International Law — codified in Article 38 of the ICJ Statute: (1) international conventions, (2) international custom (state practice + opinio juris), (3) general principles of law, (4) judicial decisions and teachings of publicists (subsidiary means only).
• Statehood — fixed by the Montevideo Convention, 1933: permanent population, defined territory, effective government, capacity to enter into relations with other states.
• Treaty Law — governed by the Vienna Convention on the Law of Treaties, 1969 (VCLT). Pacta sunt servanda binds parties; jus cogens norms (genocide, slavery, torture, aggression) cannot be contracted out of — a conflicting treaty is void under VCLT Article 53.

High-yield pointers: (i) Custom needs two elements, not one. (ii) The declaratory theory of recognition is the dominant view, not the constitutive theory. (iii) LAT asks 1–2 questions from this theme; expect a definition or principle-application MCQ.

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Sources of International Law

Article 38(1) of the ICJ Statute lists four sources in strict hierarchy. Treaties (conventions) bind only the parties that have expressed consent to be bound. Customary international law binds all states — even non-parties — once two elements coexist: (a) state practice, sufficiently widespread, consistent and durable, and (b) opinio juris sive necessitatis, the belief that the practice is legally obligatory. Classic customs include the prohibition of aggression, the law of the sea freedom-of-navigation rule, and diplomatic inviolability. General principles of law (e.g., nemo judex in causa sua, audi alteram partem, estoppel, unjust enrichment) fill gaps where treaties and custom are silent. Judicial decisions and juristic writings are subsidiary means for determining rules — they are not themselves sources.

Statehood and Recognition

Under the Montevideo Convention, 1933, Article 1, a state must possess: a permanent population, a defined territory, an effective government, and the capacity to enter into relations with other states. The declaratory theory (dominant view) holds that statehood arises the moment these criteria are met; recognition by other states is merely a political acknowledgment. The constitutive theory treats recognition as a legal prerequisite — it remains a minority academic position.

Treaty Law (VCLT 1969)

Treaties are formed through negotiation, adoption, authentication, and consent to be bound by signature, ratification, accession, acceptance or approval. Pacta sunt servanda (Article 26) requires good-faith performance. Interpretation under Articles 31–32 begins with the ordinary meaning in context, in light of object and purpose; travaux préparatoires is supplementary. A treaty conflicting with a jus cogens norm is void under Article 53.

Concept	Rule	Authority
Customary law	Practice + opinio juris	Art. 38(1)(b), ICJ Statute
Jus cogens	Non-derogable peremptory norms	Art. 53, VCLT
Statehood	Four Montevideo criteria	Montevideo Conv., 1933
Treaty binding force	Good-faith performance	Art. 26, VCLT

Typical LAT Question Patterns

Expect MCQs testing: identification of opinio juris as a custom element, declaratory vs constitutive distinction, identification of jus cogens norms, or classification of a given rule as treaty/custom/principle.

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Subjects vs Objects of International Law

Traditionally, only states — and a handful of international organizations such as the UN and ICRC — are primary subjects (holders of rights and duties under international law). Individuals, corporations and NGOs were classified as objects. Modern developments — human rights treaties, individual criminal responsibility before the ICC, refugee law — have shifted individuals into a limited subject status without making them full subjects.

State Responsibility and Attribution

A state incurs international responsibility when an act or omission constitutes a breach of an international obligation and is attributable to it. Attribution covers state organs (Nicaragua v. USA, 1986), persons or groups exercising elements of governmental authority, and insurrectional movements whose conduct is later adopted by the state. Responsibility triggers the obligations to cease the breach, provide assurances/non-repetition, and make reparation (restitution, compensation, satisfaction).

Jurisdiction — Territorial, Personal, Universal

Territorial jurisdiction (the default) covers acts within a state’s borders. Personal (nationality) jurisdiction covers nationals abroad. Passive principle protects nationals harmed abroad. Universal jurisdiction allows any state to try the gravest crimes (piracy, genocide, crimes against humanity, torture, war crimes) regardless of where committed or the offender’s nationality.

Common Mistakes in LAT

• Treating judicial decisions as a primary source — they are subsidiary.
• Forgetting that recognition is declaratory, not constitutive.
• Confusing pacta sunt servanda (binding force) with jus cogens (non-derogability).
• Citing VCLT articles wrongly — the voidness of a jus-cogens-conflicting treaty is Article 53, not 26.

Practice Prompts

1. A treaty authorises the use of force to acquire territory. Is it valid under international law? State the rule and the article.
2. A coastal state claims 200-nm territorial waters. Identify the relevant source category and the elements a LAT setter would test.

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