1. Sources of international law

2. Notion of sources
Legal processes and methods for the creation of international law
International Court of Justice (ICJ), Art. 38 of the Statute
1. The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply:

3. 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) subject to provisions of Article 59, judicial decisions and the teachings of the most qualified publicists of the various nations, as subsidiary means for the determination of rules of law.

4. Customary law Objective (material) element: state practice
Subjective (psychological) element: conviction of states, that their conduct is governed by law
„Opinio iuris (sive necessitatis)”

5. Potential forms of state practice
Diplomatic correspondance
Policy statements
Press releases
Official manuals on legal questions
National laws
Judgments of domestic courts
Practice of international organizations

6. Modalities of state practice
Duration: depends on the circumstances, but requires repetition (no instant practice)
Uniformity and generality
1969. ICJ. North Sea Continental Shelf cases: ‘both extensive and virtually uniform’
1986. ICJ. Nicaragua: ‘conduct of states should, in general, be consistent with such rules’
Acceptance of states whose interests are specifically affected (”deeper of set of footprints”)

7. Protest, acquiescence and change
1984. ICJ. Gulf of Maine: acquiescence is ‘equal to tacit recognition manifested by unilateral conduct which the other party may interpret as consent’
Generally, if states acquiesce in the development of new customary rules it can be deemed as reinforcing it
BUT: states may not protest for different reasons!
Persistent objector: objection against a newly emerging customary rule since its inception, the new norm is inapplicable to the objector

8. General principles of law (recognised by civilised nations)
Certain legal principles that can be found in all major legal systems (continental, common law, Asian etc.)
Eg: binding force of treaties, finality of judgments (res judicata), good faith (bona fides), compensation (indemnity)

9. Ius cogens Art. 53. of Vienna Convention on the Law of Treaties
A norm accepted and recognized by the international community of states as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character.

10. Erga omnes ICJ. Barcelona Traction case
Erga omnes obligations: owed to the international community as such
Legal norms which protect the entire international community, it is the legal interest of all states to enforce them
Prohibition of genocide, slavery, aggression, racial discrimination, right to self-determination, humanitarian rules

11. Resolutions of international organizations
Usually non-binding except for member states
UN General Assembly resolutions: might be evidence of custom if
(i) predominant majority of states - including states whose interest are specially affected -,
(ii) repeatedly,
(iii) adopt it with the same content.
Moreover, they might constitute authoritative interpretation of the UN Charter.
SC resolutions: binding if adopted with reference to breach or threat to peace or aggression.

12. Soft law
Role: not legal norm but might be important for the development of international law (e.g. international environmental law)
2 types:
- Non-binding terms in a binding treaty, e.g. „The parties will endeavour..”, „attempt”
- Apparently binding language but the parties only wanted a political agreement. E.g Helsinki Final Act.

13. Relationship of international law and domestic (municipal) law
Dualism: international law and domestic law are separate legal orders, cannot overrule each other
International legal rules become domestic norms through transformation
Monism: international law and domestic law comprise of one single legal system
Incorporation: international law is automatically part of the law of the land