Learning objective 1: Where can you find sources of
international law?
Art. 38 of the Statute of the International Court of Justice
a. International conventions
It’s the most direct way states create rights and obligations under international law and it’s the only
instrument available to states that want to enter into a legal relationship. The legal-basis is state
consent and a treaty only creates legal obligations for the consenting states.
- Pacta sund servanda = states must honour their treaty-based obligations
- Constituent treaty = a treaty that established an international organization
b. Custom law
c. General principles
It was to make sure that the court would be able to decide to a case even if an answer was not
possible to be found in custom or treaty law. But now, the ICJ never relied solely on general
principles, always together with custom or treaty. General principles also regulate the interaction
among legal norms.
d. Judicial decision
It is only a subsidiary source of law, they help to identify what the law is
A B C = law creating
D = law identifying
Learning objective 2: What is customary law?
Customary law is based on the everyday interaction of states. it arises when a particular way of
behaving is:
1. Followed as a general principle among states (the way things are) – objective element
2. Accepted by those states as legally binding (opinio juris) – subjective element
Objective element – state practice
Consistent repetition of certain behaviour that is either physical or verbal or legal practise. State
practice can be divided in 3 elements:
1. Generally consistency
The state practice needs to be reasonably uniform. Important is the general consistency of
the core of that conduct. Als long as the conduct is generally consistent with the rule, and the
inconsistent conduct treated as a breach of the rule rather than an indicator of the
recognition of a new rule, the conduct may suffice (Nicaragua Case 186).
2. Duration (but not fundamental)
The ICJ stated that the passage of only a short period of time is not necessarily a bar to the
formation of a new rule of custom law (North Sea Continental Shelf case 74).
3. Generality
How widespread participation in practise must be. Unanimity is not required, practise should
include the majority of states, and perhaps even more. The practise of those state whose
interests are especially affected are the most relevant (North Sea Continental Shelf case 73).
States can object to an emerging rule of international law, they are called the persistent objectors.
There are limits, they cannot object to the emerging of peremptory norms, imperative norms and jus
international law?
Art. 38 of the Statute of the International Court of Justice
a. International conventions
It’s the most direct way states create rights and obligations under international law and it’s the only
instrument available to states that want to enter into a legal relationship. The legal-basis is state
consent and a treaty only creates legal obligations for the consenting states.
- Pacta sund servanda = states must honour their treaty-based obligations
- Constituent treaty = a treaty that established an international organization
b. Custom law
c. General principles
It was to make sure that the court would be able to decide to a case even if an answer was not
possible to be found in custom or treaty law. But now, the ICJ never relied solely on general
principles, always together with custom or treaty. General principles also regulate the interaction
among legal norms.
d. Judicial decision
It is only a subsidiary source of law, they help to identify what the law is
A B C = law creating
D = law identifying
Learning objective 2: What is customary law?
Customary law is based on the everyday interaction of states. it arises when a particular way of
behaving is:
1. Followed as a general principle among states (the way things are) – objective element
2. Accepted by those states as legally binding (opinio juris) – subjective element
Objective element – state practice
Consistent repetition of certain behaviour that is either physical or verbal or legal practise. State
practice can be divided in 3 elements:
1. Generally consistency
The state practice needs to be reasonably uniform. Important is the general consistency of
the core of that conduct. Als long as the conduct is generally consistent with the rule, and the
inconsistent conduct treated as a breach of the rule rather than an indicator of the
recognition of a new rule, the conduct may suffice (Nicaragua Case 186).
2. Duration (but not fundamental)
The ICJ stated that the passage of only a short period of time is not necessarily a bar to the
formation of a new rule of custom law (North Sea Continental Shelf case 74).
3. Generality
How widespread participation in practise must be. Unanimity is not required, practise should
include the majority of states, and perhaps even more. The practise of those state whose
interests are especially affected are the most relevant (North Sea Continental Shelf case 73).
States can object to an emerging rule of international law, they are called the persistent objectors.
There are limits, they cannot object to the emerging of peremptory norms, imperative norms and jus
