Probleem 3
Bronnen:
- A. Hendriksen – International Law – Chapter 2, §4 & Chapter 3, §9
- Military and Paramilitary Activities in and against Nicaragua
- Legality of the threat of the use of nuclear weapons
- North Sea continental shelf case
- The SS Lotus case
1. What is customary international law?
Custom law are habits that are expected to be followed. The absent of an international lawmaker made custom an
important source of international law. Custom law is based on everyday interaction of the states and has the ability to
adapt to new circumstances. International custom law arises when:
1. Followed as a general practice among states
2. Accepted by those states as legally binding
A custom law binds all states, including states that haven’t taken part of the formation. Customary law can also develop
regionally.
The objective element – state practice
To get a custom law, there must be a consistent repetition of a particular behavior. In theory, all state acts may be taken
into consideration. But verbal acts must be public, and internal documents and memoranda do not qualify as a states
practice. A state practice can be divided into three elements:
- Consistency = the behavior must be consistent. However, minor departures from a collective uniformity may be
acceptable (‘settle practice’). In the Nicaragua case the Court stated that it is not to be expected that states have
acted ‘with complete consistency’.
- Duration = the custom must be lived by for a long time. The passage of a short period of time is not necessarily a
bar to the formation of new custom law (North Sea Continential Shelf cases). However, sometimes it happens
that instant custom is made by a certain event, for example the 9/11 attacks.
- Generality = practice should include a majority of states. Besides the determination of how many states, it is also
important to determine which states. A state may avoid being bound by an emerging customary rule by
persistently objecting to the practice. The law therefore protects the imposition by a majority of the other states
of new obligations upon it while allowing that majority to develop the law without having to wait for acceptance.
Persistently objecting only applies to new and emerging custom rules. In the North Sea Continental Shelf Cases
the court stated thar the practice by states ‘whose interest are specially affected’ is particularly relevant.
The subjective requirement – opinio juris
Opinio juris sive necessitatis = state practice only creates a binding custom when it is accepted as law
The subjective requirement is to differentiate between acts motivated by a desire to honor a legal obligation and to those
that are not. According to the International Law Association, the existence of sufficient general and representative state
practice is usually sufficient to create a binding custom, and opinio juris is usually only looked for if there is reason to
believe that a behavior has non-legal motivations (SS Lotus case). There is a difference between behavior at a time when a
rule begins to be formed and behavior at a time when it has already been formed. In the Nicaragua case, the court
decided that the subject element is important when there is a breach from customary rule, and the case will depend on
the justification offered.
In the SS Lotus case the Turkish government procecuted a French citizen who was involved in a collusion between two
ships. The French believed that the state that has woven the flag has jurisdiction (opinio juris). But, according to the court,
both states may exercise concurrent jurisdiction over this matter because there is no rule of international law in regard to
collision cases to the effect that criminal proceedings are exclusively within the jurisdiction of the state whose flag is
flown.
2. Which has priority: treaties or customary international law?
When a treaty codifies customary law, the parties will be bound by both, while non-parties are only bound by customary
law. A treaty can also develop customary law, when this happens, non-parties will be bound to the treaty and customary
law when they develop along the lines of the treaty. When a treaty and a custom law says the same this is called ‘parallel
obligations. When this happens, the treaty and the custom law can coexist (Nicaragua). When the treaty and customary
law conflicts, the one which has norms that has a peremptory/jus cogens character prevails. Normally a treaty prevails
Bronnen:
- A. Hendriksen – International Law – Chapter 2, §4 & Chapter 3, §9
- Military and Paramilitary Activities in and against Nicaragua
- Legality of the threat of the use of nuclear weapons
- North Sea continental shelf case
- The SS Lotus case
1. What is customary international law?
Custom law are habits that are expected to be followed. The absent of an international lawmaker made custom an
important source of international law. Custom law is based on everyday interaction of the states and has the ability to
adapt to new circumstances. International custom law arises when:
1. Followed as a general practice among states
2. Accepted by those states as legally binding
A custom law binds all states, including states that haven’t taken part of the formation. Customary law can also develop
regionally.
The objective element – state practice
To get a custom law, there must be a consistent repetition of a particular behavior. In theory, all state acts may be taken
into consideration. But verbal acts must be public, and internal documents and memoranda do not qualify as a states
practice. A state practice can be divided into three elements:
- Consistency = the behavior must be consistent. However, minor departures from a collective uniformity may be
acceptable (‘settle practice’). In the Nicaragua case the Court stated that it is not to be expected that states have
acted ‘with complete consistency’.
- Duration = the custom must be lived by for a long time. The passage of a short period of time is not necessarily a
bar to the formation of new custom law (North Sea Continential Shelf cases). However, sometimes it happens
that instant custom is made by a certain event, for example the 9/11 attacks.
- Generality = practice should include a majority of states. Besides the determination of how many states, it is also
important to determine which states. A state may avoid being bound by an emerging customary rule by
persistently objecting to the practice. The law therefore protects the imposition by a majority of the other states
of new obligations upon it while allowing that majority to develop the law without having to wait for acceptance.
Persistently objecting only applies to new and emerging custom rules. In the North Sea Continental Shelf Cases
the court stated thar the practice by states ‘whose interest are specially affected’ is particularly relevant.
The subjective requirement – opinio juris
Opinio juris sive necessitatis = state practice only creates a binding custom when it is accepted as law
The subjective requirement is to differentiate between acts motivated by a desire to honor a legal obligation and to those
that are not. According to the International Law Association, the existence of sufficient general and representative state
practice is usually sufficient to create a binding custom, and opinio juris is usually only looked for if there is reason to
believe that a behavior has non-legal motivations (SS Lotus case). There is a difference between behavior at a time when a
rule begins to be formed and behavior at a time when it has already been formed. In the Nicaragua case, the court
decided that the subject element is important when there is a breach from customary rule, and the case will depend on
the justification offered.
In the SS Lotus case the Turkish government procecuted a French citizen who was involved in a collusion between two
ships. The French believed that the state that has woven the flag has jurisdiction (opinio juris). But, according to the court,
both states may exercise concurrent jurisdiction over this matter because there is no rule of international law in regard to
collision cases to the effect that criminal proceedings are exclusively within the jurisdiction of the state whose flag is
flown.
2. Which has priority: treaties or customary international law?
When a treaty codifies customary law, the parties will be bound by both, while non-parties are only bound by customary
law. A treaty can also develop customary law, when this happens, non-parties will be bound to the treaty and customary
law when they develop along the lines of the treaty. When a treaty and a custom law says the same this is called ‘parallel
obligations. When this happens, the treaty and the custom law can coexist (Nicaragua). When the treaty and customary
law conflicts, the one which has norms that has a peremptory/jus cogens character prevails. Normally a treaty prevails
