PUBLIC INTERNATIONAL LAW
2025-2026
Introduction to Public International Law
Core Themes
• The nature and sources of international law
• The role and recognition of different subjects in international law
• Foundational principles from key cases (Lotus and Wimbledon)
• Treaty law and its interpretation under the Vienna Convention
Subjects of International Law
Primary Subjects
• States: Full international legal personality; sovereignty, equality, and independence are
foundational.
• Individuals: Recognized through human rights treaties and international criminal law.
• International Organizations: Accepted as subjects since the League of Nations and UN.
• Others with Limited Personality:
o NGOs and groups (contested status)
o Indigenous peoples (growing recognition)
o Liberation movements (historically relevant during decolonization)
o Multinational corporations (functional personality in investment law)
Key Distinctions
• States are “born” subjects; others are created through law or treaties.
• Universal personality applies only to states; others require recognition.
• International personality ≠ domestic legal personality
, Public International Law
Statehood Criteria (Montevideo Convention)
Outlined by James Crawford:
• Permanent population
• Defined territory
• Effective government
• Capacity to enter into international relations
Example: Palestine’s partial recognition (e.g., passport acceptance) illustrates how recognition can exist
without full statehood.
Sources of International Law (ICJ Statute, Article 38)
1. International conventions (treaties)
2. International custom (general practice accepted as law)
3. General principles of law (recognized by civilized nations)
4. Subsidiary means: judicial decisions and scholarly writings
Foundational Cases
1. S.S. Lotus Case (1927)
• Principle: International law is a permissive system.
• Key Quote: “Restrictions upon the independence of States cannot therefore be presumed.”
• Implication: States are free to act unless explicitly prohibited by law.
2. S.S. Wimbledon Case (1923)
• Principle: Sovereignty is compatible with international obligations.
• Key Quote: “The right of entering into international engagements is an attribute of State
sovereignty.”
• Implication: States voluntarily limit their sovereignty by entering treaties.
Page 2
, Public International Law
Treaty Law (Vienna Convention on the Law of Treaties)
Definition (Art. 2(1)(a))
• A treaty is a written agreement between states governed by international law.
Key Provisions
• Art. 26 – Pacta Sunt Servanda: Treaties must be performed in good faith.
• Art. 31–32 – Interpretation:
o Ordinary meaning in context and purpose
o Supplementary means (e.g., preparatory work) if ambiguity arises
• Art. 52: Treaties procured by force are void.
• Art. 54: Termination by treaty provisions or mutual consent
• Art. 61–64: Grounds for termination (e.g., impossibility, armed conflict, jus cogens)
Treaty Types
• Convention, Charter, Protocol, Pact, Covenant, Agreement
Conceptual Tensions
• Positivist view: Law is created by state consent; morality or common sense are not valid sources.
• Critique: Customary law may be imposed on non-consenting states; consent can be coerced.
Page 3
, Public International Law
Autonomous Weapons Systems (AWS) in International
Law
Core Focus
• Legal challenges posed by autonomous weapons
• Compatibility with International Humanitarian Law (IHL)
• Gaps in accountability and treaty regulation
• Normative and institutional responses
What Are Autonomous Weapons Systems?
Definition:
Weapons that, once activated, can select and engage targets without further human intervention.
Categories:
Type Description
Human-in-the-loop Semi-autonomous: human authorizes each attack
Human-on-the-loop Supervised autonomy: human can override
Human-out-of-the-loop Fully autonomous: no human control or oversight
Examples:
• Phalanx CIWS (US): intercepts projectiles automatically
• HARPY (Israel): targets radar installations
• Lancet-3 (Russia): loitering munition with autonomous targeting
• KARGU (Turkey): rotary drone with autonomous strike capability
Page 4
2025-2026
Introduction to Public International Law
Core Themes
• The nature and sources of international law
• The role and recognition of different subjects in international law
• Foundational principles from key cases (Lotus and Wimbledon)
• Treaty law and its interpretation under the Vienna Convention
Subjects of International Law
Primary Subjects
• States: Full international legal personality; sovereignty, equality, and independence are
foundational.
• Individuals: Recognized through human rights treaties and international criminal law.
• International Organizations: Accepted as subjects since the League of Nations and UN.
• Others with Limited Personality:
o NGOs and groups (contested status)
o Indigenous peoples (growing recognition)
o Liberation movements (historically relevant during decolonization)
o Multinational corporations (functional personality in investment law)
Key Distinctions
• States are “born” subjects; others are created through law or treaties.
• Universal personality applies only to states; others require recognition.
• International personality ≠ domestic legal personality
, Public International Law
Statehood Criteria (Montevideo Convention)
Outlined by James Crawford:
• Permanent population
• Defined territory
• Effective government
• Capacity to enter into international relations
Example: Palestine’s partial recognition (e.g., passport acceptance) illustrates how recognition can exist
without full statehood.
Sources of International Law (ICJ Statute, Article 38)
1. International conventions (treaties)
2. International custom (general practice accepted as law)
3. General principles of law (recognized by civilized nations)
4. Subsidiary means: judicial decisions and scholarly writings
Foundational Cases
1. S.S. Lotus Case (1927)
• Principle: International law is a permissive system.
• Key Quote: “Restrictions upon the independence of States cannot therefore be presumed.”
• Implication: States are free to act unless explicitly prohibited by law.
2. S.S. Wimbledon Case (1923)
• Principle: Sovereignty is compatible with international obligations.
• Key Quote: “The right of entering into international engagements is an attribute of State
sovereignty.”
• Implication: States voluntarily limit their sovereignty by entering treaties.
Page 2
, Public International Law
Treaty Law (Vienna Convention on the Law of Treaties)
Definition (Art. 2(1)(a))
• A treaty is a written agreement between states governed by international law.
Key Provisions
• Art. 26 – Pacta Sunt Servanda: Treaties must be performed in good faith.
• Art. 31–32 – Interpretation:
o Ordinary meaning in context and purpose
o Supplementary means (e.g., preparatory work) if ambiguity arises
• Art. 52: Treaties procured by force are void.
• Art. 54: Termination by treaty provisions or mutual consent
• Art. 61–64: Grounds for termination (e.g., impossibility, armed conflict, jus cogens)
Treaty Types
• Convention, Charter, Protocol, Pact, Covenant, Agreement
Conceptual Tensions
• Positivist view: Law is created by state consent; morality or common sense are not valid sources.
• Critique: Customary law may be imposed on non-consenting states; consent can be coerced.
Page 3
, Public International Law
Autonomous Weapons Systems (AWS) in International
Law
Core Focus
• Legal challenges posed by autonomous weapons
• Compatibility with International Humanitarian Law (IHL)
• Gaps in accountability and treaty regulation
• Normative and institutional responses
What Are Autonomous Weapons Systems?
Definition:
Weapons that, once activated, can select and engage targets without further human intervention.
Categories:
Type Description
Human-in-the-loop Semi-autonomous: human authorizes each attack
Human-on-the-loop Supervised autonomy: human can override
Human-out-of-the-loop Fully autonomous: no human control or oversight
Examples:
• Phalanx CIWS (US): intercepts projectiles automatically
• HARPY (Israel): targets radar installations
• Lancet-3 (Russia): loitering munition with autonomous targeting
• KARGU (Turkey): rotary drone with autonomous strike capability
Page 4
