International law
Week 1
1.1 Chapter 2 - ‘The making of international law
Introduction
International law is largely made by states, reflecting their sovereignty and the consent-based
nature of the system. Since no authority stands above states, law derives from their voluntary
agreement rather than imposition.
However, this makes universal lawmaking difficult; participation is optional, and global
interests often compete with national interests.
There is no single lawmaking treaty, but Article 38 of the ICJ Statute lists the recognized
sources of international law, serving as the core framework though not exhaustive. Modern
developments show international organizations and soft law mechanisms increasingly
participate in lawmaking, expanding beyond the original list.
Two Ships (or Perhaps Three): Lotus and Wimbledon
Two early PCIJ cases — SS Lotus (1927) and SS Wimbledon (1923) — illustrate the
foundation of international law’s positivist and consent-based character.
Lotus (1927)
- Involved a collision at sea between a French and a Turkish vessel, resulting in the
death of Turkish nationals.
- France objected when Turkey prosecuted the French officer, claiming it violated
international law.
- The PCIJ ruled in favor of Turkey, declaring that what is not prohibited in
international law is permitted.
- The “Lotus principle” thus became foundational: states are free to act unless an
explicit rule restricts them.
- This case embodies the positivist, consent-based nature of international law —
emphasizing state freedom and voluntarism.
Wimbledon (1923)
- Concerned Germany’s refusal to let an Allied ship pass through the Kiel Canal despite
a treaty obligation.
- Germany claimed that fulfilling treaty obligations violated its sovereignty.
- The Court rejected this argument, declaring that binding oneself by treaty is an
exercise of sovereignty, not its negation.
Together, Lotus and Wimbledon encapsulate the paradox of sovereignty in international
law:
- Sovereignty is both the foundation of and limitation upon state behavior.
- International law exists not against sovereignty, but because of it — it is a
manifestation of states’ will to cooperate within limits.
Article 38 ICJ Statute
Article 38(1) defines the primary sources of international law:
a. Treaties
, b. Customary international law
c. General principles of law
d. Judicial decisions and scholarly writings (as subsidiary means)
Klabbers calls Article 38 the “orthodox catalogue” of international law’s sources, but he
stresses several important qualifications:
- It is descriptive, not prescriptive - it summarizes existing practice rather than creating
it.
- No hierarchy exists between treaties and custom; they coexist and sometimes overlap.
- The general principles act as a gap-filling mechanism, providing continuity where
neither treaties nor custom apply.
- Judicial and scholarly contributions help identify law but do not create it.
Klabbers also highlights that Article 38 omits modern forms of norm creation, such as UN
resolutions, decisions of international organizations, and soft law instruments. This
underscores how the doctrine of sources is conservative, yet constantly evolving.
Treaties
Treaties are the clearest and most formal source of international law. They rest upon:
● Consent of states (pacta sunt servanda)
● Binding force upon ratification
● Reciprocal obligations
Treaties may serve multiple purposes:
● They can codify existing custom (e.g., the Vienna Convention on Diplomatic
Relations).
● They can create new institutions (e.g., the UN Charter).
● They may regulate technical or economic matters (e.g., trade or environment).
Treaties are expressions of sovereignty: by voluntarily binding themselves, states
demonstrate their freedom to choose obligations.
Customary Law
Customary international law is the oldest source of international law and consists of:
1.State practice (what states do)
2.Opinio juris (what states believe they are legally obliged to do)
Both objective practice and subjective belief are essential; mere habit or coincidence does not
create law. Custom develops gradually, through consistent behavior over time, especially
among major or specially affected states.
However, custom can also change rapidly in times of technological or political
transformation, such as the emergence of cyber norms or environmental principles.
Custom flexibility allows international law to adapt, but it also creates ambiguity,
determining the existence of a customary rule often involves interpretative judgment.
,The Method of Custom: The Paquete Habana
The Paquete Habana (1900): a U.S. Supreme Court case involving the seizure of Cuban
fishing vessels during the Spanish–American War.
The Court ruled that customary international law protected coastal fishing vessels from
capture, citing centuries of consistent state practice.
Justice Gray’s famous dictum — “International law is part of our law” — illustrates how
courts can identify and apply customary norms even without written treaties. This case
demonstrates how judicial recognition and long-standing practice can transform moral
expectations into binding rules.
Consent and the Persistent Objector
Although custom binds all states, the persistent objector rule allows a state to opt out of a
developing norm if it consistently and clearly objects from the outset.
This doctrine preserves the voluntarist nature of international law; ensuring no state is bound
against its will.
However, this principle has practical limits:
● It cannot apply to peremptory norms (jus cogens), such as prohibitions on genocide or
slavery.
● Persistent objection is rare in practice and difficult to sustain over time.
The persistent objector doctrine illustrates both the strength (flexibility) and weakness
(fragmentation) of a consent-based system.
On Lawbreaking and Lawmaking
International law evolves not only through compliance but also through violations.
Occasionally, lawbreaking triggers lawmaking, especially when other states acquiesce in a
novel act.
For example:
● The Truman Proclamation (1945) extended U.S. sovereignty over its continental
shelf — initially controversial, but later accepted and codified in the 1958 Geneva
Conventions and UNCLOS (1982).
● Similarly, the use of outer space and Antarctic exploration produced new norms
through practice preceding regulation.
Thus, violations or innovations can act as experiments, gradually reshaping legal
expectations.
General Principles of Law
These are fundamental legal doctrines recognized by all “civilized nations”, including:
● Equity
● Good faith
● Res judicata (finality of judgment)
● Prohibition of abuse of rights
They are used primarily when no treaty or custom applies, functioning as a “safety net” to
preserve coherence in the legal system. The general principles embody moral rationality and
comparative legal reasoning, bridging domestic and international law. They also indicate that
, international law is not purely positivist, it draws upon shared legal conscience as well as
consent.
Unilateral Declarations
States may create legal obligations through clear and intentional unilateral acts.
The Nuclear Tests cases (Australia v. France, 1974) before the ICJ exemplify this: France’s
public statements declaring a halt to nuclear testing were deemed legally binding, as they
expressed an intention to be bound.
The unilateral declarations demonstrate the power of intention and good faith fundamental to
all international obligations.
Other Possible Sources and the Renewal of Sources Doctrine
Lawmaking has expanded beyond the “traditional trilogy” (treaties, custom, general
principles).
Modern law emerges from:
● UN General Assembly resolutions (e.g., the Universal Declaration of Human Rights)
● Decisions of international organizations
● Codes of conduct and soft law instruments
● Private regulatory regimes (e.g., financial or environmental standards)
These developments represent a “renewal of the sources doctrine”: the realization that
lawmaking today involves multiple actors, varied instruments, and degrees of normativity.
The distinction between “hard” and “soft” law has become blurred, as soft norms can
harden into binding obligations over time.
Final Remarks
Despite its complexity, the source's doctrine remains essential because it provides structure
and legitimacy in a decentralized system. International law continues to rest on consent, good
faith, and shared expectations, even as it evolves through new mechanisms.
Ultimately, the making of international law is a dynamic, dialogic process; balancing
sovereignty with community, and stability with change.
1.1 S.S. Lotus (PCIJ, 1927)
Facts:
● On 2 August 1926, the French ship Lotus collided with the Turkish ship
Boz-Kourt on the high seas near the island of Mitylene.
● The Boz-Kourt sank, and eight Turkish nationals died.
● Upon arrival in Constantinople, Turkish authorities arrested Lieutenant Demons, the
French officer on watch on the Lotus, and charged him with manslaughter under
Turkish law.
● France protested, claiming that only France (as the flag state of the Lotus) had
jurisdiction over incidents on the high seas involving its ship.
● The dispute was referred to the Permanent Court of International Justice (PCIJ).
Week 1
1.1 Chapter 2 - ‘The making of international law
Introduction
International law is largely made by states, reflecting their sovereignty and the consent-based
nature of the system. Since no authority stands above states, law derives from their voluntary
agreement rather than imposition.
However, this makes universal lawmaking difficult; participation is optional, and global
interests often compete with national interests.
There is no single lawmaking treaty, but Article 38 of the ICJ Statute lists the recognized
sources of international law, serving as the core framework though not exhaustive. Modern
developments show international organizations and soft law mechanisms increasingly
participate in lawmaking, expanding beyond the original list.
Two Ships (or Perhaps Three): Lotus and Wimbledon
Two early PCIJ cases — SS Lotus (1927) and SS Wimbledon (1923) — illustrate the
foundation of international law’s positivist and consent-based character.
Lotus (1927)
- Involved a collision at sea between a French and a Turkish vessel, resulting in the
death of Turkish nationals.
- France objected when Turkey prosecuted the French officer, claiming it violated
international law.
- The PCIJ ruled in favor of Turkey, declaring that what is not prohibited in
international law is permitted.
- The “Lotus principle” thus became foundational: states are free to act unless an
explicit rule restricts them.
- This case embodies the positivist, consent-based nature of international law —
emphasizing state freedom and voluntarism.
Wimbledon (1923)
- Concerned Germany’s refusal to let an Allied ship pass through the Kiel Canal despite
a treaty obligation.
- Germany claimed that fulfilling treaty obligations violated its sovereignty.
- The Court rejected this argument, declaring that binding oneself by treaty is an
exercise of sovereignty, not its negation.
Together, Lotus and Wimbledon encapsulate the paradox of sovereignty in international
law:
- Sovereignty is both the foundation of and limitation upon state behavior.
- International law exists not against sovereignty, but because of it — it is a
manifestation of states’ will to cooperate within limits.
Article 38 ICJ Statute
Article 38(1) defines the primary sources of international law:
a. Treaties
, b. Customary international law
c. General principles of law
d. Judicial decisions and scholarly writings (as subsidiary means)
Klabbers calls Article 38 the “orthodox catalogue” of international law’s sources, but he
stresses several important qualifications:
- It is descriptive, not prescriptive - it summarizes existing practice rather than creating
it.
- No hierarchy exists between treaties and custom; they coexist and sometimes overlap.
- The general principles act as a gap-filling mechanism, providing continuity where
neither treaties nor custom apply.
- Judicial and scholarly contributions help identify law but do not create it.
Klabbers also highlights that Article 38 omits modern forms of norm creation, such as UN
resolutions, decisions of international organizations, and soft law instruments. This
underscores how the doctrine of sources is conservative, yet constantly evolving.
Treaties
Treaties are the clearest and most formal source of international law. They rest upon:
● Consent of states (pacta sunt servanda)
● Binding force upon ratification
● Reciprocal obligations
Treaties may serve multiple purposes:
● They can codify existing custom (e.g., the Vienna Convention on Diplomatic
Relations).
● They can create new institutions (e.g., the UN Charter).
● They may regulate technical or economic matters (e.g., trade or environment).
Treaties are expressions of sovereignty: by voluntarily binding themselves, states
demonstrate their freedom to choose obligations.
Customary Law
Customary international law is the oldest source of international law and consists of:
1.State practice (what states do)
2.Opinio juris (what states believe they are legally obliged to do)
Both objective practice and subjective belief are essential; mere habit or coincidence does not
create law. Custom develops gradually, through consistent behavior over time, especially
among major or specially affected states.
However, custom can also change rapidly in times of technological or political
transformation, such as the emergence of cyber norms or environmental principles.
Custom flexibility allows international law to adapt, but it also creates ambiguity,
determining the existence of a customary rule often involves interpretative judgment.
,The Method of Custom: The Paquete Habana
The Paquete Habana (1900): a U.S. Supreme Court case involving the seizure of Cuban
fishing vessels during the Spanish–American War.
The Court ruled that customary international law protected coastal fishing vessels from
capture, citing centuries of consistent state practice.
Justice Gray’s famous dictum — “International law is part of our law” — illustrates how
courts can identify and apply customary norms even without written treaties. This case
demonstrates how judicial recognition and long-standing practice can transform moral
expectations into binding rules.
Consent and the Persistent Objector
Although custom binds all states, the persistent objector rule allows a state to opt out of a
developing norm if it consistently and clearly objects from the outset.
This doctrine preserves the voluntarist nature of international law; ensuring no state is bound
against its will.
However, this principle has practical limits:
● It cannot apply to peremptory norms (jus cogens), such as prohibitions on genocide or
slavery.
● Persistent objection is rare in practice and difficult to sustain over time.
The persistent objector doctrine illustrates both the strength (flexibility) and weakness
(fragmentation) of a consent-based system.
On Lawbreaking and Lawmaking
International law evolves not only through compliance but also through violations.
Occasionally, lawbreaking triggers lawmaking, especially when other states acquiesce in a
novel act.
For example:
● The Truman Proclamation (1945) extended U.S. sovereignty over its continental
shelf — initially controversial, but later accepted and codified in the 1958 Geneva
Conventions and UNCLOS (1982).
● Similarly, the use of outer space and Antarctic exploration produced new norms
through practice preceding regulation.
Thus, violations or innovations can act as experiments, gradually reshaping legal
expectations.
General Principles of Law
These are fundamental legal doctrines recognized by all “civilized nations”, including:
● Equity
● Good faith
● Res judicata (finality of judgment)
● Prohibition of abuse of rights
They are used primarily when no treaty or custom applies, functioning as a “safety net” to
preserve coherence in the legal system. The general principles embody moral rationality and
comparative legal reasoning, bridging domestic and international law. They also indicate that
, international law is not purely positivist, it draws upon shared legal conscience as well as
consent.
Unilateral Declarations
States may create legal obligations through clear and intentional unilateral acts.
The Nuclear Tests cases (Australia v. France, 1974) before the ICJ exemplify this: France’s
public statements declaring a halt to nuclear testing were deemed legally binding, as they
expressed an intention to be bound.
The unilateral declarations demonstrate the power of intention and good faith fundamental to
all international obligations.
Other Possible Sources and the Renewal of Sources Doctrine
Lawmaking has expanded beyond the “traditional trilogy” (treaties, custom, general
principles).
Modern law emerges from:
● UN General Assembly resolutions (e.g., the Universal Declaration of Human Rights)
● Decisions of international organizations
● Codes of conduct and soft law instruments
● Private regulatory regimes (e.g., financial or environmental standards)
These developments represent a “renewal of the sources doctrine”: the realization that
lawmaking today involves multiple actors, varied instruments, and degrees of normativity.
The distinction between “hard” and “soft” law has become blurred, as soft norms can
harden into binding obligations over time.
Final Remarks
Despite its complexity, the source's doctrine remains essential because it provides structure
and legitimacy in a decentralized system. International law continues to rest on consent, good
faith, and shared expectations, even as it evolves through new mechanisms.
Ultimately, the making of international law is a dynamic, dialogic process; balancing
sovereignty with community, and stability with change.
1.1 S.S. Lotus (PCIJ, 1927)
Facts:
● On 2 August 1926, the French ship Lotus collided with the Turkish ship
Boz-Kourt on the high seas near the island of Mitylene.
● The Boz-Kourt sank, and eight Turkish nationals died.
● Upon arrival in Constantinople, Turkish authorities arrested Lieutenant Demons, the
French officer on watch on the Lotus, and charged him with manslaughter under
Turkish law.
● France protested, claiming that only France (as the flag state of the Lotus) had
jurisdiction over incidents on the high seas involving its ship.
● The dispute was referred to the Permanent Court of International Justice (PCIJ).
