Questions about Customary international law
Short answers, pulled from the story.
What is customary international law and how does it differ from treaty law?
Customary international law consists of international legal obligations arising from established or usual international practices, often unwritten, as opposed to formal written treaties or conventions. While treaties bind only the states that sign and ratify them, customary international law can bind all states, including those that never formally agreed to a rule, as long as those states have not persistently objected to it.
What are the two requirements for a rule to become customary international law?
A rule becomes customary international law when two conditions are both met: first, there must be a state practice that is sufficiently widespread, representative, and consistent, with a significant number of states using and relying on it; second, states must hold opinio juris, meaning they act out of a belief that they are legally obligated to follow the rule, not merely out of habit or courtesy.
What is jus cogens and how does it relate to customary international law?
Jus cogens, Latin for "compelling law", refers to peremptory norms of international law that no treaty or conflicting rule can override. All jus cogens norms qualify as customary international law through their adoption by states, but not all customary international law rises to this level. Examples of jus cogens violations include piracy, slavery, torture, genocide, war of aggression, and crimes against humanity.
When were the laws of war codified and what role does customary international law still play?
The laws of war, known as jus in bello, were codified in the Hague Conventions of 1899 and 1907 and later in the Geneva Conventions. However, those conventions do not cover every legal matter that can arise in armed conflict. Article 1(2) of Additional Protocol I states that customary international law governs armed conflict situations not addressed by other agreements, and in 1993 the United Nations Security Council adopted the Geneva Conventions as customary international law.
What evidence does the International Law Commission recognize for identifying customary international law?
In 1950, the International Law Commission listed treaties, decisions of national and international courts, national legislation, opinions of national legal advisors, diplomatic correspondence, and the practice of international organizations as forms of evidence of customary international law. In 2018 the Commission adopted Conclusions on Identification of Customary International Law with commentaries, which the United Nations General Assembly welcomed and encouraged states to disseminate as widely as possible.
Can a state avoid being bound by customary international law through persistent objection?
A state that consistently and persistently objects to a customary rule may avoid being bound by it in ordinary circumstances. However, if a rule has risen to the level of jus cogens, persistent objection offers no protection. States can also depart from ordinary customary international law by enacting treaties or domestic legislation that conflicts with it, but no such departure is permitted for peremptory norms.