Why This Matters
In 1648, the Peace of Westphalia ended thirty years of religious war across Europe and quietly created something new: a system where sovereign states agreed to treat each other as equals bound by common rules. No court enforced those rules. No police executed them. Yet states followed them, most of the time. International Law was born not from a legislature but from necessity. Today it governs everything from the airspace above your head to the satellites orbiting the planet. The Osmania University examiner tests this chapter because it forces the student to grapple with the hardest question in jurisprudence: can law exist without a sovereign to enforce it? This chapter gives you the framework to answer that question precisely and confidently.
Chapter Overview
This chapter answers four questions:
- What is International Law? The leading definitions from Oppenheim, Starke, and Brierly and what distinguishes each.
- Is International Law really law? The Austin objection, the rebuttal, and the judicial answer.
- What is the nature and basis of International Law? The theories that explain why states obey it.
- What is its scope and importance? The domains it governs and why it matters in the contemporary world.
Definition of International Law
This section examines the three most authoritative definitions and extracts the essential elements that examiners expect.
The term "International Law" was coined by Jeremy Bentham in 1780 in his Introduction to the Principles of Morals and Legislation. Before Bentham, the discipline was called the Law of Nations, a translation of the Roman jus gentium. The change in terminology was not merely cosmetic. Bentham's formulation shifted the focus from nations as cultural communities to states as legal persons interacting under a body of rules.
B entham (coined the term, 1780)
O ppenheim (classic positivist definition)
S tarke (modern comprehensive definition)
S avigny (natural law tradition)
For examination: Oppenheim and Starke are the two definitions most frequently reproduced. Know both verbatim.
Oppenheim's Definition
Oppenheim defines International Law as the body of customary and conventional rules which are considered legally binding by civilised states in their intercourse with each other.
Three elements emerge from this definition. First, the rules must be either customary (arising from consistent state practice) or conventional (arising from treaty). Second, states must consider these rules legally binding, not merely morally persuasive. Third, the original formulation used "civilised states," a term now abandoned as Eurocentric and incompatible with the universality of modern international law.
Oppenheim's definition is positivist in orientation. It focuses on what states actually do, not on what they ought to do. Its limitation is that it excludes individuals and international organisations as subjects of international law, a position that modern international law has firmly rejected.
Starke's Definition
J.G. Starke defines International Law as that body of law which is composed for its greater part of the principles and rules of conduct which states feel themselves bound to observe, and do commonly observe, in their relations with each other.
Starke's definition is deliberately broader than Oppenheim's. It adds three important extensions. It includes rules relating to the functioning of international institutions. It includes rules relating to individuals and non-state entities insofar as those rules concern the rights and duties of states. It acknowledges the importance of "feeling bound," capturing the psychological element of opinio juris that custom requires.
| Dimension | Oppenheim | Starke |
|---|---|---|
| Scope of subjects | States only | States + international institutions + individuals |
| Orientation | Strict positivism | Broader, includes opinio juris |
| Currency | Dated (civilised states) | Contemporary |
| Utility for exams | Classic definition, cite for historical accuracy | Preferred modern definition |
Brierly's Definition
J.L. Brierly defines International Law as the body of rules and principles of action which are binding upon civilised states in their relations with one another.
Brierly's definition is the most concise of the three. It emphasises that international law consists of both rules (specific obligations) and principles (broader normative standards). The inclusion of "principles" alongside "rules" anticipates the role of general principles of law as a source of international law under Article 38(1)(c) of the ICJ Statute.
Nature of International Law: Is it Really Law?
This section addresses the most contested question in the chapter and the one most likely to appear as a Part B question.
The Austin Objection
John Austin, in his Province of Jurisprudence Determined (1832), argued that International Law is not law properly so called but merely positive international morality.
Austin's argument rests on his command theory of law. For Austin, law is a command issued by a sovereign, backed by a sanction. He identified three elements: a determinate human superior (sovereign), a command addressed to legal subjects, and a sanction for disobedience. International Law fails all three tests. There is no world sovereign. No command issues from a superior. No reliable enforcement mechanism exists. On Austin's framework, international law is no different from the rules of a club: persuasive, perhaps even binding in a social sense, but not legally obligatory.
📋 Facts: A German vessel, the Franconia, collided with a British ship within three miles of the English coast, causing death. The captain was prosecuted in an English court.
⚖️ Issue: Whether English courts had jurisdiction over a foreigner's act committed on a foreign vessel within British territorial waters.
🏛️ Held: The Court, by a majority, held that English courts had no jurisdiction. International custom regarding territorial waters had not been incorporated into English law by statute or judicial decision.
🎯 Principle: International Law does not automatically become part of domestic law; it requires adoption or transformation. Illustrates the Austin critique: without domestic incorporation, international rules lack enforceability.
🔗 Full case notes
The Rebuttal: Why IL Is Law
The better view, endorsed by most modern jurists, is that International Law is genuine law, though of a different structural character from municipal law.
Five arguments rebut Austin:
First, the consensual basis argument. States create international law through consent expressed in treaties and custom. The binding force derives not from a superior's command but from the consent of equals. This is not unusual: contract law binds parties not because a sovereign commanded the contract but because the parties agreed.
Second, the effectiveness argument. States do, in fact, overwhelmingly comply with international law. As Louis Henkin observed, almost all nations observe almost all principles of international law almost all of the time. The absence of a centralised enforcement mechanism does not mean absence of compliance.
Third, the judicial recognition argument. National courts regularly apply international law as law. The Privy Council, the US Supreme Court, and the Supreme Court of India have all treated international law as a binding legal source.
Fourth, the institutional argument. The UN Charter, the ICJ Statute, the WTO Dispute Settlement Mechanism, and hundreds of treaty-based institutions create a sophisticated legal architecture that operates as law in practice.
Fifth, the jus cogens argument. Certain norms of international law are now accepted as peremptory: they bind all states absolutely regardless of consent. The prohibition on genocide, torture, and slavery cannot be contracted out of. This is precisely what Austin said law required: obligatory force.
📋 Facts: A British company claimed that Britain, having annexed the South African Republic, was bound by obligations the Republic had undertaken to pay compensation to the company.
⚖️ Issue: Whether the British Crown was bound by international obligations of the annexed state.
🏛️ Held: The Court held that international law is part of English law, but only insofar as it has been adopted by the courts. Unincorporated international obligations do not automatically bind the Crown.
🎯 Principle: International Law has legal status but domestic incorporation remains the threshold for municipal enforcement. Frequently cited as the English position on IL-Municipal relationship.
🔗 Full case notes
📋 Facts: A French vessel, the Lotus, collided on the high seas with a Turkish vessel. Turkey arrested the French officer when the ship docked in Constantinople and prosecuted him.
⚖️ Issue: Whether Turkey had jurisdiction to prosecute a French national for an act committed on a French vessel on the high seas.
🏛️ Held: The PCIJ held that Turkey had not violated international law. In the absence of a prohibitive rule, states are free to exercise jurisdiction. Sovereignty implies freedom of action unless restricted.
🎯 Principle: The Lotus principle: whatever is not prohibited by international law is permitted. States are sovereign and free unless international law specifically restricts them. This principle has since been modified but remains foundational.
🔗 Full case notes
Incorrect framing. Austin identified a genuine structural difference between international and municipal law. The correct answer is that his positivist framework is too narrow, not that his observations are factually wrong. Modern scholars like Hart distinguished between primary and secondary rules, acknowledging that IL lacks secondary rules but still qualifies as a legal system. Give Austin credit, then rebut him with Hart.
Theories on the Basis of International Law
This section explains why states feel legally bound by international law — the theoretical foundations that examiners test in Part B.
Natural Law Theory
The natural law school holds that international law derives its binding force from universal principles of reason and justice that exist independently of state consent.
Hugo Grotius (1583 to 1645), the Father of International Law, grounded the law of nations in natural law in his foundational work De Jure Belli ac Pacis (On the Law of War and Peace, 1625). Grotius argued that certain rules of conduct among nations are dictated by right reason and would bind states even if God did not exist. The rule pacta sunt servanda (agreements must be kept) is not binding because states agreed to it; it is binding because reason demands it.
W ar must be just (jus ad bellum)
W ar must be conducted justly (jus in bello)
P acts must be kept (pacta sunt servanda)
De Jure Belli ac Pacis (1625). These three ideas underpin the entire modern law of armed conflict and treaty law.
Positivist Theory
The positivist school holds that international law derives its binding force exclusively from the express or implied consent of states.
Vattel, Bynkershoek, and Moser developed the positivist tradition. On this view, a state is bound only by rules it has consented to, either through treaty (express consent) or through custom (implied consent by consistent practice). The strength of positivism is its explanatory clarity: it grounds international law in verifiable state conduct. Its weakness is that it struggles to explain jus cogens norms, which bind states regardless of consent.
Consent Theory (Voluntarism)
Closely related to positivism, the consent theory holds that the will of the state is the ultimate source of all international obligation. Triepel and Anzilotti developed the doctrine of Vereinbarung: international law arises from the common will of states, which is different from and superior to the individual will of any single state. This common will, once formed through treaty or custom, binds all participating states.
Auto-Limitation Theory
Jellinek proposed that states voluntarily limit their own sovereignty by accepting international law. States are not externally compelled; they choose to restrict their freedom because reciprocal restriction serves their interests. This theory explains treaty compliance well but struggles with customary law that binds states regardless of individual voluntary limitation.
| Theory | Basis of Binding Force | Key Jurist | Weakness |
|---|---|---|---|
| Natural Law | Reason and justice | Grotius | Vague; no mechanism to identify content |
| Positivism | State consent | Vattel, Anzilotti | Cannot explain jus cogens |
| Consent/Voluntarism | Common will of states | Triepel | Circular: states bind themselves |
| Auto-Limitation | Self-imposed restriction | Jellinek | Cannot explain non-consensual custom |
Scope and Importance of International Law
This section maps the domains governed by international law and explains its contemporary significance.
Scope: What International Law Governs
International law today extends far beyond its original focus on inter-state relations. Starke identifies the following principal domains:
State relations: The foundational domain. Rules governing diplomacy, treaty-making, territorial sovereignty, state responsibility, and the use of force between states.
Law of the sea: The legal regime governing territorial waters, the contiguous zone, the exclusive economic zone, the continental shelf, and the high seas, now codified primarily in UNCLOS 1982.
Air and outer space law: The Chicago Convention (1944) governs civil aviation. The Outer Space Treaty (1967) governs activities beyond the atmosphere, establishing that outer space is the province of all mankind.
International organisations: The UN Charter (1945) and the constitutive instruments of specialised agencies create a complex institutional framework with legal personality distinct from member states.
📋 Facts: Count Folke Bernadotte, the UN mediator in Palestine, was assassinated in Jerusalem in 1948. The General Assembly asked the ICJ whether the UN had the capacity to bring an international claim against the responsible state for injuries to its agent.
⚖️ Issue: Whether the United Nations possesses international legal personality distinct from its member states.
🏛️ Held: The UN is an international person. It is a subject of international law, capable of possessing international rights and duties and of maintaining its rights by bringing international claims, even against non-member states.
🎯 Principle: International organisations are subjects of international law. Legal personality in the international system is not confined to states, confirming the expansion beyond the purely state-centric model.
🔗 Full case notes
Human rights: The Universal Declaration (1948), the two International Covenants (1966), and a network of treaty bodies have made individual human rights a central concern of international law, breaking the traditional state-centric model.
International criminal law: The Rome Statute (1998) established the ICC, creating individual criminal responsibility for genocide, crimes against humanity, and war crimes under international law directly.
Importance of International Law
International Law performs five functions that no alternative mechanism can replicate.
It maintains international order by providing agreed rules that reduce uncertainty and prevent disputes from escalating to conflict. It protects state sovereignty by codifying the principle of sovereign equality and non-intervention. It facilitates cooperation by providing the legal framework for treaties on trade, environment, health, and communications. It protects individuals by establishing minimum standards of treatment that states owe to persons regardless of nationality. It provides dispute resolution through the ICJ, WTO panels, UNCLOS tribunals, and ad hoc arbitration.
📋 What it addresses: The foundational instrument of the post-World War II international order. Creates the United Nations and its principal organs.
📌 Key Articles: Article 2(1): sovereign equality of all members. Article 2(4): prohibition on threat or use of force. Article 2(7): non-intervention in domestic jurisdiction. Article 51: right of self-defence.
🎯 Significance: Transformed international law from a decentralised system of bilateral rules into a collective security architecture. The prohibition on force in Article 2(4) is now jus cogens.
Common Confusions
Austin conflated the two but modern jurisprudence separates them sharply. International morality refers to standards states ought to observe. International law refers to standards states are legally obligated to observe, with institutional mechanisms for compliance and sanction. The content may overlap; the legal character differs.
Grotius systemised and theorised it; he did not invent it. Rules governing ambassadors, treaties, and conduct in war predate Grotius by centuries. His contribution was the first comprehensive theoretical framework, which is why he is called the Father, not the Inventor, of International Law.
Enforcement is not synonymous with a centralised police force. International law is enforced through diplomatic pressure, economic sanctions, ICJ judgments, Security Council action, treaty withdrawal rights, and reputational costs. The absence of a world police does not equal absence of enforcement.
Key Takeaways
Three Key Definitions:
- Oppenheim: customary and conventional rules, states only, positivist
- Starke: broader, includes institutions and individuals, adds opinio juris
- Brierly: rules and principles, most concise
The Austin Debate:
- Austin: IL is positive morality, not law (no sovereign, no command, no sanction)
- Rebuttal: consensual basis, effectiveness, judicial recognition, institutions, jus cogens
- Hart's refinement: IL lacks secondary rules but still qualifies as a legal system
Four Theories of Basis:
- Natural Law (Grotius): reason and justice
- Positivism (Vattel): state consent
- Voluntarism (Triepel): common will
- Auto-Limitation (Jellinek): self-imposed restriction
Memory Hooks:
- BOSS: four key definers
- Grotius Three Pillars: war just, war conducted justly, pacta sunt servanda
- Oppenheim vs Starke four-dimension distinction table
- Four Theories table: basis, jurist, weakness
Define International Law
The term "International Law" was coined by Jeremy Bentham in 1780. Two definitions dominate examination answers.
Oppenheim defines International Law as the body of customary and conventional rules which are considered legally binding by civilised states in their intercourse with each other. This is the classic positivist definition, limited to states as subjects.
Starke offers a broader definition: International Law is that body of law composed for its greater part of principles and rules of conduct which states feel themselves bound to observe, and do commonly observe, in their relations with each other, including rules relating to international institutions and individuals. Starke's definition is preferred today because it reflects the expanded scope of modern international law beyond purely inter-state relations.
Both definitions share three common elements: a body of rules, legal bindingness, and applicability to the conduct of states in their mutual relations. The key advance in Starke is the inclusion of international organisations and individuals as partial subjects, reflecting developments since 1945.
Part A (6 marks)
Is International Law True Law? Austin's Objection
John Austin, in Province of Jurisprudence Determined (1832), argued that International Law is not law properly so called but merely positive international morality. On Austin's command theory, law requires a determinate sovereign, a command, and a sanction. International Law has none of these: there is no world sovereign, no centralised command, and no reliable enforcement mechanism.
The better view is that Austin's framework is too narrow. Five reasons support this. First, law can derive binding force from consent rather than command: treaty obligations bind by agreement, as contracts do. Second, states comply with international law overwhelmingly in practice. Third, national courts regularly apply international law as binding legal authority. Fourth, institutions like the ICJ, WTO, and ICC operate as genuine legal mechanisms. Fifth, jus cogens norms bind states regardless of consent, satisfying even Austin's requirement of obligatory force.
H.L.A. Hart's refinement is most persuasive: international law lacks secondary rules but this makes it a primitive legal system, not a non-legal system.
Part B (15 marks)
Discuss the Definition, Nature, and Basis of International Law / Is International Law Truly Law? / Theories and Future of International Law
- Definition: Oppenheim (rules accepted by civilised states); Brierly (rules of conduct binding states)
- Article 38(1) ICJ Statute: authoritative enumeration of sources
- Austin's Challenge: IL is "positive international morality"; lacks sovereign command, sanctions, courts
- Three theories of basis: Natural Law (Grotius), Positivism (Vattel, Bentham), Eclectic (modern)
- Subjects: states (primary), international organisations, individuals (partial subjects)
- Lotus Case 1927: states free to act unless prohibited by IL
- Modern features: jus cogens, erga omnes, international institutions, individual responsibility