WEEK 5: INTERNATIONAL LAW
International law is the body of rules governing relations between states and international
actors (Klabbers, International Law, 2017, ch 1).
It functions as a “rulebook for global conduct” — ensuring peace, cooperation, and accountability.
Effect and Purpose:
• Maintains peace and security (UN Charter).
• Promotes human rights and humanitarian standards.
• Regulates trade, environment, communications, and war.
• Provides dispute resolution mechanisms (ICJ, ICC).
(Hall 2016) argues that international law remains “law” because it is recognised, applied, and accepted as binding
by the community of states, even without centralised enforcement.
2. DISTINCTION BETWEEN PUBLIC & PRIVATE INTERNATIONAL LAW
Public International Law (PILic)
Rules governing state-to-state relations and international organisations.
Covers almost all international issues — trade, borders, use of force, environmental protection, and human
rights.
(Klabbers 2017): Public international law is “the language through which the international community governs
itself.”
Institutions:
• United Nations (UN) – especially the Security Council for collective security.
• International Court of Justice (ICJ) – resolves disputes between states.
• World Trade Organization (WTO) – regulates international trade.
Private International Law (PILiv)
Also called Conflict of Laws, it governs cross-border private disputes — between individuals, companies, or other
private entities.
(Mortensen et al., Private International Law in Australia, 2015) defines it as “the set of rules that determine which
country’s law applies when private legal relations cross borders.”
Core Legal Questions for Global Lawyers:
1. Jurisdiction – Can this court hear the case?
2. Choice of law – Which country’s law governs?
3. Recognition & enforcement – Will a foreign judgment be recognised here?
,These questions are central for global lawyers advising on contracts, torts, family law, and commercial disputes
involving multiple jurisdictions.
3. PRIMARY SOURCES OF PUBLIC INTERNATIONAL LAW
(As set out in Article 38(1) of the Statute of the International Court of Justice)
1. International Conventions (Treaties) – Article 38(1)(a)
“International conventions, whether general or particular, establishing rules expressly recognised by the contesting
states.”
Definition:
Formal written agreements between states that are governed by international law.
(Hall 2016) defines a treaty as “an agreement binding in law upon the parties that consent to it.”
Examples:
• UN Charter (1945) – foundational treaty for global governance.
• Vienna Convention on the Law of Treaties (1969) – “treaty on treaties”; defines formation, validity, and
termination.
• WHO Framework Convention on Tobacco Control (2005) – used in Tobacco Plain Packaging litigation.
Exam Point: Treaties are binding only on states that consent to them — unlike customary law, which binds all.
2. Customary International Law – Article 38(1)(b)
“International custom, as evidence of a general practice accepted as law.”
Two Elements (Klabbers 2017; Hall 2016):
1. State practice – consistent and widespread behaviour by states.
2. Opinio juris – belief that such behaviour is legally required, not merely habitual.
Examples:
• Prohibition of genocide and torture.
• Immunity of diplomats.
• Freedom of navigation in international waters.
Case Authority: North Sea Continental Shelf Cases (ICJ, 1969) – confirmed both practice and opinio juris are
necessary.
Exam Tip: Customary international law binds all states, even those not party to a relevant treaty (unless they have
persistently objected).
, 3. General Principles of Law Recognised by Civilised Nations – Article 38(1)(c)
These are fundamental legal principles common to major national systems.
(Hall 2016) explains these fill gaps when no treaty or custom exists.
Examples:
• Good faith (bona fide).
• Estoppel.
• Equity and due process.
• Res judicata (finality of judgments).
Exam Point: These ensure that international law has completeness and can adapt to new issues without new
treaties.
4. Judicial Decisions and Scholarly Writings (Subsidiary Means) – Article 38(1)(d)
“Subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists.”
Purpose:
Used to clarify or interpret primary sources (not create law).
Examples:
• ICJ judgments – e.g., Nicaragua v United States (1986) clarified customary law on the use of force.
• Academic commentary – e.g., Hall (2016), Klabbers (2017), Mitchell & Beard (2009) are secondary
interpretive aids.
Exam Tip: Mention that subsidiary sources guide courts and states but are not binding.
4. INSTITUTIONAL STRUCTURE OF THE PUBLIC INTERNATIONAL LAW SYSTEM
Key Bodies:
• United Nations (UN) – Main global forum; Security Council decisions (Chapter VII, UN Charter) can be
binding.
• International Court of Justice (ICJ) – Judicial organ of the UN; settles legal disputes (Article 38(1) sources
guide its judgments).
• International Criminal Court (ICC) – prosecutes individuals for international crimes.
• World Trade Organization (WTO) – enforces global trade rules.
(Klabbers 2017) stresses these institutions are decentralised — cooperation replaces compulsion.
(Hall 2016) highlights the absence of a world legislature and the reliance on consent and reciprocity as the
foundation of international law’s authority.
International law is the body of rules governing relations between states and international
actors (Klabbers, International Law, 2017, ch 1).
It functions as a “rulebook for global conduct” — ensuring peace, cooperation, and accountability.
Effect and Purpose:
• Maintains peace and security (UN Charter).
• Promotes human rights and humanitarian standards.
• Regulates trade, environment, communications, and war.
• Provides dispute resolution mechanisms (ICJ, ICC).
(Hall 2016) argues that international law remains “law” because it is recognised, applied, and accepted as binding
by the community of states, even without centralised enforcement.
2. DISTINCTION BETWEEN PUBLIC & PRIVATE INTERNATIONAL LAW
Public International Law (PILic)
Rules governing state-to-state relations and international organisations.
Covers almost all international issues — trade, borders, use of force, environmental protection, and human
rights.
(Klabbers 2017): Public international law is “the language through which the international community governs
itself.”
Institutions:
• United Nations (UN) – especially the Security Council for collective security.
• International Court of Justice (ICJ) – resolves disputes between states.
• World Trade Organization (WTO) – regulates international trade.
Private International Law (PILiv)
Also called Conflict of Laws, it governs cross-border private disputes — between individuals, companies, or other
private entities.
(Mortensen et al., Private International Law in Australia, 2015) defines it as “the set of rules that determine which
country’s law applies when private legal relations cross borders.”
Core Legal Questions for Global Lawyers:
1. Jurisdiction – Can this court hear the case?
2. Choice of law – Which country’s law governs?
3. Recognition & enforcement – Will a foreign judgment be recognised here?
,These questions are central for global lawyers advising on contracts, torts, family law, and commercial disputes
involving multiple jurisdictions.
3. PRIMARY SOURCES OF PUBLIC INTERNATIONAL LAW
(As set out in Article 38(1) of the Statute of the International Court of Justice)
1. International Conventions (Treaties) – Article 38(1)(a)
“International conventions, whether general or particular, establishing rules expressly recognised by the contesting
states.”
Definition:
Formal written agreements between states that are governed by international law.
(Hall 2016) defines a treaty as “an agreement binding in law upon the parties that consent to it.”
Examples:
• UN Charter (1945) – foundational treaty for global governance.
• Vienna Convention on the Law of Treaties (1969) – “treaty on treaties”; defines formation, validity, and
termination.
• WHO Framework Convention on Tobacco Control (2005) – used in Tobacco Plain Packaging litigation.
Exam Point: Treaties are binding only on states that consent to them — unlike customary law, which binds all.
2. Customary International Law – Article 38(1)(b)
“International custom, as evidence of a general practice accepted as law.”
Two Elements (Klabbers 2017; Hall 2016):
1. State practice – consistent and widespread behaviour by states.
2. Opinio juris – belief that such behaviour is legally required, not merely habitual.
Examples:
• Prohibition of genocide and torture.
• Immunity of diplomats.
• Freedom of navigation in international waters.
Case Authority: North Sea Continental Shelf Cases (ICJ, 1969) – confirmed both practice and opinio juris are
necessary.
Exam Tip: Customary international law binds all states, even those not party to a relevant treaty (unless they have
persistently objected).
, 3. General Principles of Law Recognised by Civilised Nations – Article 38(1)(c)
These are fundamental legal principles common to major national systems.
(Hall 2016) explains these fill gaps when no treaty or custom exists.
Examples:
• Good faith (bona fide).
• Estoppel.
• Equity and due process.
• Res judicata (finality of judgments).
Exam Point: These ensure that international law has completeness and can adapt to new issues without new
treaties.
4. Judicial Decisions and Scholarly Writings (Subsidiary Means) – Article 38(1)(d)
“Subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists.”
Purpose:
Used to clarify or interpret primary sources (not create law).
Examples:
• ICJ judgments – e.g., Nicaragua v United States (1986) clarified customary law on the use of force.
• Academic commentary – e.g., Hall (2016), Klabbers (2017), Mitchell & Beard (2009) are secondary
interpretive aids.
Exam Tip: Mention that subsidiary sources guide courts and states but are not binding.
4. INSTITUTIONAL STRUCTURE OF THE PUBLIC INTERNATIONAL LAW SYSTEM
Key Bodies:
• United Nations (UN) – Main global forum; Security Council decisions (Chapter VII, UN Charter) can be
binding.
• International Court of Justice (ICJ) – Judicial organ of the UN; settles legal disputes (Article 38(1) sources
guide its judgments).
• International Criminal Court (ICC) – prosecutes individuals for international crimes.
• World Trade Organization (WTO) – enforces global trade rules.
(Klabbers 2017) stresses these institutions are decentralised — cooperation replaces compulsion.
(Hall 2016) highlights the absence of a world legislature and the reliance on consent and reciprocity as the
foundation of international law’s authority.
