Definition, Nature and Meaning of International Law — is it 'true law'? — Public International Law Notes

Definition, Nature and Meaning of International Law — is it “true law”?

In 1832 the English jurist John Austin looked at the law between nations and declared it was not law at all — merely “positive international morality”, like the rules of a club. For nearly a century that stung. Yet when Iraq invaded Kuwait in 1990, no State said “there is no law here”. Every State — including Iraq — argued in the language of law: self-defence, aggression, Charter obligations. States do not plead morality at each other; they plead law. That instinct is the best answer to Austin.

What international law is, and why the question of “true law” arises

International law is the body of rules and principles that binds sovereign States (and, increasingly, other international persons) in their relations with one another. The reason its very status as “law” is doubted is structural, so notice the structure first. Every domestic legal system you know sits above the people it governs: a Parliament makes the rule, a court applies it, a police force enforces it. International law has none of these. There is no world Parliament, no compulsory world court, and no world police. Instead it is a horizontal order — sovereign States, each formally equal, making the rules that bind them by agreeing to them and by behaving as bound.

Because of that missing “sovereign above”, the examiner’s favourite question is evaluative: is international law true law? Austin said no. His theory of law (the command theory) held that law is the command of a sovereign, backed by a sanction. Between States there is no common superior and no organised sanction, so — for Austin — there is no law, only “positive international morality”.

The modern reply does not deny Austin’s facts; it denies his definition. Austin described one kind of law — the municipal kind — and mistook it for law itself. Law does not require a legislature and a policeman; primitive and customary legal systems bound people for centuries without either. International law behaves like law in every way that matters:

States treat it as binding — they do not claim freedom to ignore it.
When a State departs from it, it does not deny the rule; it pleads an exception (self-defence, necessity, consent). You only make excuses to a rule you accept.
It is obeyed with remarkable consistency — arguably more consistently than citizens obey the criminal law — because breach is costly (reprisals, sanctions, loss of reputation and reciprocity).
It does have sources (Art. 38 ICJ Statute), courts (the ICJ and arbitral tribunals) and sanctions (Security Council enforcement under Chapter VII of the UN Charter, self-help, countermeasures).

So the honest conclusion is: international law is a weak legal system, but it is a legal system. Conceding its weaknesses (no legislature, no compulsory jurisdiction, the veto) is what makes the defence credible — do not pretend it is as strong as municipal law.

Oppenheim: “Law of Nations or International Law is the name for the body of customary and conventional rules which are considered legally binding by civilised States in their intercourse with each other.”

In Simple Terms: International law is the set of rules — grown from custom and from treaties — that States themselves accept as legally binding (not merely moral) when they deal with one another. The key words are “legally binding” and “considered so by the States”: obligation comes from the States’ own acceptance, not from a ruler above them.

🧩 WORKED EXAMPLE — answering “Is international law true law?”

Facts. An exam asks: “International Law is not true law but only positive morality. Critically examine.”

Rule. Austin’s command theory says law needs a sovereign + sanction. The reply is that this describes municipal law only; law can rest on custom and consent.

Apply. Show the three moves: (1) state Austin’s objection fairly; (2) rebut it — States plead IL, justify departures as exceptions, obey it consistently, and IL has sources, courts and sanctions; (3) concede the weaknesses honestly.

Conclusion. International law is “true law” in a real but weaker sense — law of a horizontal, decentralised order, not a vertical one. A verdict that simply says “yes” or “no” without the reasoning scores poorly; the marks are in the reasoning.

💡 The single sentence examiners reward: “Austin defined law by the features of one system, the municipal, and then found international law wanting for lacking them — but law is a wider genus than the command of a sovereign.”

flowchart TD
    A["Is International Law 'true law'?"]
    A --> B["Austin says NO<br/>law = command of sovereign + sanction<br/>no world sovereign, so no law"]
    A --> C["Modern reply: YES (but weak)"]
    C --> D["States plead it as law"]
    C --> E["Departures pleaded as exceptions"]
    C --> F["Has sources, courts, sanctions"]
    C --> G["Obeyed consistently"]
    classDef box fill:#e8f0fe,stroke:#333,color:#111;
    class A,B,C,D,E,F,G box;

Case Laws

West Rand Central Gold Mining Co. v. R. (1905) — English courts will apply a rule of international law only where it has been established by sufficient State practice; confirms IL is treated as law but must be proved.
The Paquete Habana (1900, US Supreme Court) — “International law is part of our law”; coastal fishing vessels are exempt from capture as prize by settled custom, showing custom operating as binding law.

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