1. Introduction to public international law

2. International law State A International law: treaties, customary law
State B
European law: ECT, directives, regulations
National legislation
Bylaws, regulations, ordinances

3. Art.38 ICJ Statute
“1. 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 recognized by the contesting states;
b. international custom, as evidence of a general practice accepted as law;
c. the general principles of law recognized by civilized nations;
d. … 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.”

4. Public international law
System of rules and principles that govern the relationship between States and other subjects of international law (e.g. the United Nations or the European Community)
Primary sources: treaties and customary law
Subsidiary means
Soft law: contributes to the formation of customary law as well as provide evidence of opinio juris

5. Treaties
Agreements between States (and other entities under international law) bind the participating Parties
Conventions, pacts, protocols, covenants etc
Trade, diplomacy, postal services, transboundary emissions, the use of outer space, war, global environment, control and jurisdiction over territory, human rights, international crimes etc
No hierarchy between different international treaties – except the Charter of the United Nations (Constitution of the international community?)
Treaty interpretation through different means including the intention of the parties at the time the treaty was concluded and the subsequent practice of the parties in its application
Conflicts may be addressed in the treaties or subject to Vienna Convention rules

6. Customary law
Customary international law is derived from the consistent practice of States accompanied by opinio juris - the conviction of States that this practice is required by a legal obligation.
In addition to state behaviour, judgments of international courts and academic research are traditionally used as persuasive sources for evidencing customary international law.

7. Treaty & customary law Customary and treaty law are complementary
Treaties regularly contain codifications of customary law while subsequent State practice can develop the provision of a treaty further
Treaties and the practice of States may also lead to the creation of new rules of customary law
What constitutes applicable international law is however often a question of interpretation…

8. Law & practice Art.94 para.1 UNCLOS (Duties of the flag State)
“Every State shall effectively exercise its jurisdiction and control in administrative, technical and social matters over ships flying its flag.”
Art.27 para.3 UN Charter: “Decisions of the Security Council on all other matters shall be made by an affirmative vote of nine members including the concurring votes of the permanent members;…”.
Prohibition of force (Art.2 para.4 UN Charter) unless
- UN Chapter VII enforcement measures,
- Self defence or
- Humanitarian intervention? (US doctrine)

9. Compliance Treaty monitoring and compliance
Security Council to protect peace and security
Jurisdiction of international courts and tribunal
Peer pressure, certainty in international relations and reputation
Investment and donor support

10. Areas of the law Branches or Fields of Public International Law 10
International Human Rights Law (IHRL)
International Humanitarian Law (IHL) (Law of Armed Conflict)
International Criminal Law
International Environmental Law
International Economic/Monetary Law
International Maritime Law
International Law of the Sea
International Trade Law
International Labour
Law
International Law relating to Space
International Refugee Law
International Law relating to disarmament
International Law of Public International Organizations/ Institutions 10

11. International & domestic law
Monism – Dualism – Nihilism
International law > domestic law
Formation and interpretation of domestic law
Use of international law by courts
Human rights instruments
- application pre ratification
- avenues for redress
Creation of processes and institutions: Institute of Biodiversity Conservation and Research to implement Ethiopia’s obligation to the Convention of Biological Diversity; designation of Wetlands etc.

12. Domestic relevance
Direct impact on people’s lives (Security Council resolutions, CDM)
Relevance for the development of domestic legislation, jurisprudence, admin procedures
Reference for sustainable development and good governance
Campaigning tool
Involvement of civil society in development, implementation and compliance monitoring compliance