INTERNATIONAL CUSTOMARY LAW
The LOTUS case:
A French vessel hit a Turkish vessel in the high seas. The men on the Turkish ship died. When the French
vessel landed in Turkey, the captain was arrested and sentenced with manslaughter (1926) (in a Turkish
court, under Turkish law). Later, both countries went to the PCIJ under the claim: was Turkey’s
performed jurisdiction (arresting the French captain) a violation of international law? The court found
turkey not guilty, as it did not violate anything and there is no international law that forbids the use of
jurisdiction in case of maritime conflict. The decision was criticized and some years later new
conventions were signed to codify that on the high seas, jurisdiction depends on the flag.
- Definitions: international customs are a set of unwritten rules that has been developed over time
because of repeated actions performed by states. It has two elements:
- Many of the rules that originally governed such diverse areas as jurisdiction over territory,
freedom of the high seas, the privileges and immunities of states and diplomats, the law of land
warfare (jus in bello), and the rights of aliens have stemmed from customary practice.
1) State practice: constitutes any act from the 3 state powers (jurisdiction, legislation, executive)
that recognize the custom. It should also be for a long period of time and for multiple times
(durable). Also, a large number of states must recognize/practice the custom in the same
manner (min. 10). Objections to the custom are relevant. A state may exempt itself from the
application of a new customary law by consistently objecting to the norm’s formation and
proposing opposing customary laws. Consent is required (no single nation can change the law
[of the sea]). [durability, consistency, persistence objector]
2) Opinio juris: the psychological/mental element. The state should feel a legal obligation to
abide by the custom and not just out of courtesy or habit. It must believe that it is obligated
to abide by the existence of the rule of law requiring it
TREATIES AND CUSTOMS
- A treaty is a separate source of international law which creates obligations between states. It does
not have a direct result on customary law, but they can influence each other
- Before the end of the 19th century, customs came first, however later the codification process
started and customs started being codified through treaties or conventions.
- The treaty can crystallize customary law by giving consent to the new rule and helping it to
receive the necessary recognition
- A treaty can also be a starting point for other customary law when the content of the treaty is
confirmed by future state practice
- Generally, states believe they are bound by contracts (treaties) and not customs.
- The state can have a customary opinio juris if it is convinced that it acts not because of treaties
but because of a customary law.
- When a treaty repeats existing customary law, it is like making a formal statement about
something that was already common practice among nations
- When a treaty does something that was the missing piece needed to officially recognize a ruse as
a customary law, it triggers a customary law and the thing becomes recognized as common
practice (like the chemical weapons convention in 1993 which prohibits the usage, production,
acquisition, transfer (etc) of chemical weapons and also verifies in case a country is doing so.
Before this, the usage of chemical weapons was generally frowned upon but this treaty went
beyond than just disapproving of the usage of these weapons.)
The LOTUS case:
A French vessel hit a Turkish vessel in the high seas. The men on the Turkish ship died. When the French
vessel landed in Turkey, the captain was arrested and sentenced with manslaughter (1926) (in a Turkish
court, under Turkish law). Later, both countries went to the PCIJ under the claim: was Turkey’s
performed jurisdiction (arresting the French captain) a violation of international law? The court found
turkey not guilty, as it did not violate anything and there is no international law that forbids the use of
jurisdiction in case of maritime conflict. The decision was criticized and some years later new
conventions were signed to codify that on the high seas, jurisdiction depends on the flag.
- Definitions: international customs are a set of unwritten rules that has been developed over time
because of repeated actions performed by states. It has two elements:
- Many of the rules that originally governed such diverse areas as jurisdiction over territory,
freedom of the high seas, the privileges and immunities of states and diplomats, the law of land
warfare (jus in bello), and the rights of aliens have stemmed from customary practice.
1) State practice: constitutes any act from the 3 state powers (jurisdiction, legislation, executive)
that recognize the custom. It should also be for a long period of time and for multiple times
(durable). Also, a large number of states must recognize/practice the custom in the same
manner (min. 10). Objections to the custom are relevant. A state may exempt itself from the
application of a new customary law by consistently objecting to the norm’s formation and
proposing opposing customary laws. Consent is required (no single nation can change the law
[of the sea]). [durability, consistency, persistence objector]
2) Opinio juris: the psychological/mental element. The state should feel a legal obligation to
abide by the custom and not just out of courtesy or habit. It must believe that it is obligated
to abide by the existence of the rule of law requiring it
TREATIES AND CUSTOMS
- A treaty is a separate source of international law which creates obligations between states. It does
not have a direct result on customary law, but they can influence each other
- Before the end of the 19th century, customs came first, however later the codification process
started and customs started being codified through treaties or conventions.
- The treaty can crystallize customary law by giving consent to the new rule and helping it to
receive the necessary recognition
- A treaty can also be a starting point for other customary law when the content of the treaty is
confirmed by future state practice
- Generally, states believe they are bound by contracts (treaties) and not customs.
- The state can have a customary opinio juris if it is convinced that it acts not because of treaties
but because of a customary law.
- When a treaty repeats existing customary law, it is like making a formal statement about
something that was already common practice among nations
- When a treaty does something that was the missing piece needed to officially recognize a ruse as
a customary law, it triggers a customary law and the thing becomes recognized as common
practice (like the chemical weapons convention in 1993 which prohibits the usage, production,
acquisition, transfer (etc) of chemical weapons and also verifies in case a country is doing so.
Before this, the usage of chemical weapons was generally frowned upon but this treaty went
beyond than just disapproving of the usage of these weapons.)
