What is International Law?

1. ISSUE — is international law really law?

The foundational question is whether the rules and principles binding upon states in their relations — what Brierly defined and Crawford still defines as "international law" — is properly described as law. The doubt is structural: no world legislature, no compulsory court of general jurisdiction, no police, no executive to enforce judgments against a recalcitrant state. If law is what Austin took it to be — the command of a sovereign backed by sanction — international law fails every limb.

The thesis: Austin misdescribes the phenomenon. International law is law of a different kind — horizontal, consensual, sourced rather than legislated, decentralised. Its existence is recognised in Article 38(1) ICJ Statute 1945; its operating logic is set by the Lotus presumption (PCIJ, 1927) that restrictions on state independence cannot be presumed. Sovereignty is the organising principle; consent is the mechanism. The "is it law?" question survives only if Austin was right about what law is — Hart, Higgins and Crawford say he was not.

2. RULE — sources, sovereignty, and Article 38

Following Brierly and Crawford, PIL is the body of rules and principles binding upon states in their relations. Crawford in Brownlie's Principles (9th ed 2019) complicates that immediately: international law also addresses IOs, individuals (human rights, international criminal law), and, in narrower domains, corporations and armed groups. The state-centric definition is doctrinally orthodox and analytically incomplete. The canonical sources provision is Article 38(1) ICJ Statute 1945:

"The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply: (a) international conventions, whether general or particular, establishing rules expressly recognised by the contesting states; (b) international custom, as evidence of a general practice accepted as law; (c) the general principles of law recognised by civilised nations; (d) subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of law."

— Statute of the International Court of Justice 1945, Article 38(1).

Three points. First, Article 38(1) is a list addressed to the ICJ, not a constitutional provision; whether unilateral acts, soft law, IO decisions, or peremptory norms belong beside it is a live debate. Second, the categories are unequal: treaty (a) and custom (b) do the doctrinal work; general principles (c) plug gaps; judicial decisions and writings (d) are subsidiary. Third — Drew's lecture point — Article 38 is not self-sufficient. To identify custom you need rules about how to find rules: opinio juris, state practice, specially-affected states, persistent objectors. The architecture is layered.

Underwriting it is state sovereignty. Article 2(1) UN Charter records the "sovereign equality" of all members; Article 2(7) reserves matters "essentially within the domestic jurisdiction of any state" from UN intervention. Sovereignty is why PIL is consent-based: a state is bound only by rules it has accepted (treaty) or that have crystallised into custom — with the modern qualification that jus cogens norms (genocide, slavery, torture, aggression) bind regardless of consent.

The operating presumption follows. In Lotus the PCIJ held that "rules of law binding upon States … emanate from their own free will" and that "restrictions upon the independence of States cannot … be presumed". Liberty is the default; constraint requires demonstration. D'Amato argues this is overdrawn — widespread uncontested practice can constrain without express consent — but the basic frame still does the work.

3. APPLICATION — Lotus, Reparation, custom

Read together: Lotus sets the default; North Sea and Asylum discipline custom; Nicaragua shows consent need not be contemporaneous; Reparation shows the legal community is not only states. The modern overlay — jus cogens (Arts 53, 64 VCLT 1969); erga omnes (Barcelona Traction ICJ 1970, dictum); individual criminal responsibility (Nuremberg 1945–46; Rome Statute 1998; ICC) — strains the consent model further without dismantling the Westphalian frame.

4. CRITIQUE — Austin, Hart, Koskenniemi

John Austin, in The Province of Jurisprudence Determined (1832), defined law as the command of a sovereign backed by sanction. PIL, lacking a sovereign legislator, becomes "positive morality" — opinions and sentiments about the conduct of nations. The argument stipulates what law is and excludes the inter-state phenomenon by definition. If a definition rules out a body of rules that lawyers, courts and foreign ministries continuously treat as law, the response is to revise the definition.

H.L.A. Hart's reply in The Concept of Law (1961; 2nd ed 1994): mature legal systems combine primary rules of obligation with secondary rules — a rule of recognition, rules of change, and rules of adjudication. PIL has primary rules (prohibition on use of force, diplomatic immunities, treaty interpretation) but only attenuated secondary rules: no unified rule of recognition, no centralised legislature, no compulsory court. PIL is therefore "primitive" — like the law of a small society — but not non-law. The category is law; the species is decentralised.

Hans Kelsen defended PIL as a normative order whose validity derives from a presupposed Grundnorm: validity is normative structure, not coercion. Rosalyn Higgins (Problems and Process, 1994) reframes PIL as a process of authoritative decision-making by which states, organisations and tribunals reconstitute the rules in light of community values; the Austinian search for command-and-sanction is a category mistake.

Martti Koskenniemi (From Apology to Utopia, 1989; reissued 2005) turns the screw: international legal argument oscillates between an apology for state power and unreachable utopia; each pole collapses into the other; the discipline reproduces the indeterminacy as professional argument. Indeterminacy is constitutive, not pathological.

Goldsmith and Posner (The Limits of International Law, 2005) advance a modern Austinianism: compliance is a function of state interest, not obedience. The reply is empirical (Henkin) and conceptual (Hart): a system in which states routinely treat rules as binding, justify departures in their language, and accept third-party adjudication is not mere coincidence-of-interest, even where coercive enforcement is thin.

5. EVALUATION — does it work as law?

The strongest case is empirical. Louis Henkin's line — "almost all nations observe almost all principles of international law and almost all of their obligations almost all of the time" (How Nations Behave, 2nd ed 1979) — is the one every essay should know. Compliance is overdetermined: reputation, reciprocity, repeat-play diplomacy, the costs of treaty violation, domestic incorporation. Sanction in the Austinian sense is rare; compliance is not.

Compliance is asymmetric. Weaker states bear more of the costs; permanent SC members absorb non-compliance more cheaply. The Council veto, the limited reach of ICJ compulsory jurisdiction (Art 36 Statute optional clause), and the political character of Chapter VII enforcement compound the asymmetry. PIL approximates like-cases-alike in technical regimes (ICAO, IMO, telecommunications) and falls short in others (use of force; accountability for atrocity).

Non-state actors strain the model. Individuals are both objects of obligation (Nuremberg, ICC) and bearers of rights (human rights treaties, regional regimes). Corporations are subjects of investment law and business-and-human-rights instruments. IOs have functional personality (Reparation). Armed groups bear obligations under common Article 3 of the Geneva Conventions and customary IHL.

6. CONCLUSION

International law is law: rules and principles binding upon states (and now IOs, individuals and other actors), sourced through Article 38(1), anchored in Lotus, enriched by custom that binds without express consent, peremptory norms that bind regardless, and practice that admits non-state actors. Austin mischaracterises the species; Hart's "primitive but real" is closer. Higgins: the system is in operation. Koskenniemi: operation is contested all the way down. Henkin closes the case empirically. The honest answer takes a position — PIL is law of a decentralised, consent-based kind — and defends it through Article 38, Lotus, and at least one modern strain (Reparation, Nicaragua, jus cogens) that complicates but does not falsify the claim.

Academic voices

International law is, on Austin's account, not law properly so called but "positive morality" — opinions and sentiments current among nations generally — because it lacks a sovereign legislator and a coercive sanction.

— John Austin, The Province of Jurisprudence Determined (1832), Lecture VI (paraphrase).

International law has primary rules of obligation but lacks the full set of secondary rules — a unified rule of recognition, centralised rules of change, compulsory rules of adjudication. It is therefore "primitive" but not non-law: real law in an attenuated form.

— H.L.A. Hart, The Concept of Law (Clarendon, 1961; 2nd edn 1994), Ch X (paraphrase).

"Almost all nations observe almost all principles of international law and almost all of their obligations almost all of the time."

— Louis Henkin, How Nations Behave: Law and Foreign Policy (2nd edn, Columbia UP / Council on Foreign Relations, 1979), p. 47.

International legal argument oscillates between an apology for state power and an unattainable utopia. Each pole collapses into the other; the discipline reproduces the oscillation as its mode of professional argument.

— Martti Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (Helsinki, 1989; reissued CUP, 2005) (paraphrase).

International law is not a set of rules to be retrieved and applied; it is a process of authoritative decision-making by which states, courts and tribunals reconstitute the rules in light of community values.

— Rosalyn Higgins, Problems and Process (Clarendon, 1994), Ch 1 (paraphrase).

Common pitfalls

Exam answer skeleton

1. ISSUE. Is international law really law? Thesis: yes, of a decentralised, consent-based, horizontal kind, anchored in Article 38(1) and disciplined by Lotus.
2. RULE. Define PIL (Brierly/Crawford). Article 38(1) ICJ Statute. Sovereignty (Arts 2(1), 2(7) UN Charter) as organising principle, consent as mechanism. Lotus for the default-position rule.
3. APPLICATION. Lotus (sovereignty/consent), North Sea (custom structure), Asylum (evidentiary demands), Nicaragua (treaty/custom interplay), Reparation (personality beyond states).
4. CRITIQUE. Austin (positive morality) → Hart (primitive but real) → Kelsen (validity, not coercion) → Higgins (process) → Koskenniemi (apology/utopia) → Goldsmith & Posner (rationalist).
5. EVALUATION. Henkin on compliance. Asymmetry. Modern strain: jus cogens, erga omnes, individual responsibility, non-state actors. Frame holds; species mutating.
6. CONCLUSION. Take a position. International law is law — decentralised, consent-based, primitive-but-real — but defended through the modern overlay, not just through 1927.

Checklist

• Opened with the legal issue and thesis; not with Westphalia/League history.
• Cited Article 38(1) ICJ Statute and named all four heads (treaty, custom, general principles, judicial decisions/writings as subsidiary).
• Cited Lotus (PCIJ 1927) and at least one qualification (Nicaragua; D'Amato).
• Engaged Austin (positive morality, 1832) and Hart (primitive system, 1961). Bonus: Higgins, Koskenniemi, Goldsmith & Posner.
• Cited Henkin's "almost all nations … almost all the time" line.
• Acknowledged the modern overlay: jus cogens, erga omnes, individual responsibility, IO personality (Reparation 1949), non-state actors.
• Cited Article 2(7) UN Charter on domestic jurisdiction.
• Took a position.