Customary international law

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Customary international law is an aspect of international law involving the principle of custom. Along with general principles of law and treaties, custom is considered by the International Court of Justice, jurists, the United Nations, and its member states to be among the primary sources of international law.

International law regulations governing international relations

International law is the set of rules generally regarded and accepted in relations between nations. It serves as a framework for the practice of stable and organized international relations. International law differs from state-based legal systems in that it is primarily applicable to countries rather than to individual citizens. National law may become international law when treaties permit national jurisdiction to supranational tribunals such as the European Court of Human Rights or the International Criminal Court. Treaties such as the Geneva Conventions may require national law to conform to respective parts.

Treaty express agreement under international law entered into by actors in international law

A treaty is an agreement under international law entered into by actors in international law, namely sovereign states and international organizations. A treaty may also be known as an (international) agreement, protocol, covenant, convention, pact, or exchange of letters, among other terms. Regardless of terminology, all of these forms of agreements are, under international law, equally considered treaties and the rules are the same.

International Court of Justice primary judicial organ of the United Nations

The International Court of Justice, abbreviated as ICJ, is the principal judicial organ of the United Nations (UN). It settles legal disputes between member states and gives advisory opinions to authorized UN organs and specialized agencies. It comprises a panel of 15 judges elected by the General Assembly and Security Council for nine-year terms. It is seated in the Peace Palace in The Hague, Netherlands.


Many governments accept in principle the existence of customary international law, although there are differing opinions as to what rules are contained in it.

In 1950, the International Law Commission listed the following sources as forms of evidence to customary international law: treaties, decisions of national and international courts, national legislation, opinions of national legal advisors, diplomatic correspondence, and practice of international organizations. [1]

The International Law Commission was established by the United Nations General Assembly in 1948 for the "promotion of the progressive development of international law and its codification."

Recognition of customary international law

The International Court of Justice Statute defines customary international law in Article 38(1)(b) as "a general practice accepted as law." [2] This is generally determined through two factors: the general practice of states and what states have accepted as law. [3]

There are several kinds of customary international laws recognized by states. Some customary international laws rise to the level of jus cogens through acceptance by the international community as non-derogable rights, while other customary international law may simply be followed by a small group of states. States are typically bound by customary international law regardless of whether the states have codified these laws domestically or through treaties.

Jus cogens

See jus cogens.

A peremptory norm (also called jus cogens, Latin for "compelling law") is a fundamental principle of international law which is accepted by the international community of states as a norm from which no derogation is ever permitted. These norms rooted from Natural Law principles, [4] and any laws conflicting with it should be considered null and void. [5] Examples include various international crimes; a state violates customary international law if it permits or engages in slavery, torture, genocide, war of aggression, or crimes against humanity [6]

A peremptory norm is a fundamental principle of international law that is accepted by the international community of states as a norm from which no derogation is permitted.

Latin Indo-European language of the Italic family

Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets and ultimately from the Phoenician alphabet.

The international community is a phrase used in geopolitics and international relations to refer to a broad group of people and governments of the world. It does not refer literally to all nations or states in the world. The term is typically used to imply the existence of a common point of view towards such matters as specific issues of human rights. Activists, politicians and commentators often use the term in calling for action to be taken; e.g., action against what is in their opinion political repression in a target country.

Jus cogens and customary international law are not interchangeable. All jus cogens are customary international law through their adoption by states, but not all customary international laws rise to the level of peremptory norms. States can deviate from customary international law by enacting treaties and conflicting laws, but jus cogens are non-derogable.

Codification of international customary law

Some international customary laws have been codified through treaties and domestic laws, while others are recognized only as customary law.

The laws of war, also known as jus in bello, were long a matter of customary law before they were codified in the Hague Conventions of 1899 and 1907, Geneva Conventions, and other treaties. However, these conventions do not purport to govern all legal matters that may arise during war. Instead, Article 1(2) of Additional Protocol I dictates that customary international law governs legal matters concerning armed conflict not covered by other agreements. [7] [8]

In law, codification is the process of collecting and restating the law of a jurisdiction in certain areas, usually by subject, forming a legal code, i.e. a codex (book) of law.

Geneva Conventions Treaties establishing humanitarian laws of war

The Geneva Conventions comprise four treaties, and three additional protocols, that establish the standards of international law for humanitarian treatment in war. The singular term Geneva Convention usually denotes the agreements of 1949, negotiated in the aftermath of the Second World War (1939–45), which updated the terms of the two 1929 treaties, and added two new conventions. The Geneva Conventions extensively defined the basic rights of wartime prisoners, established protections for the wounded and sick, and established protections for the civilians in and around a war-zone. The treaties of 1949 were ratified, in whole or with reservations, by 196 countries. Moreover, the Geneva Convention also defines the rights and protections afforded to non-combatants, yet, because the Geneva Conventions are about people in war, the articles do not address warfare proper—the use of weapons of war—which is the subject of the Hague Conventions, and the bio-chemical warfare Geneva Protocol.

Protocol I

Protocol I is a 1977 amendment protocol to the Geneva Conventions relating to the protection of victims of international conflicts, where "armed conflicts in which peoples are fighting against colonial domination, alien occupation or racist regimes" are to be considered international conflicts. It reaffirms the international laws of the original Geneva Conventions of 1949, but adds clarifications and new provisions to accommodate developments in modern international warfare that have taken place since the Second World War.

Generally, sovereign nations must consent in order to be bound by a particular treaty or legal norm. However, international customary laws are norms that have become pervasive enough internationally that countries need not consent in order to be bound. In these cases, all that is needed is that the state has not objected to the law. However, states that object to customary international law may not be bound by them unless these laws are deemed to be jus cogens . [9] However, in a dispute with any nation that has not affirmed the "silence implies consent" principle, any invocation of the "silence implies consent" principle involves an appeal to custom, such that if that nation does not espouse the broader premise of acknowledging the existence of customary international law, such an appeal will depend on circular reasoning ("customary international law is binding because silence implies consent, and silence implies consent because the fact that silence implies consent is one aspect of customary international law"). [10]

Consent and International Customary Law

It is commonly said that the international community is ‘anarchical’, in that there is no layer of higher government with absolute power to treat states like citizens. This is in a way unsurprising, since most states could (if pressed) rely solely on themselves for survival. States are thus in a position, unlike individual humans, to refuse the benefits and reciprocal responsibilities of participating in a community under law.

In recognition of this reality, it has long been a tenet of international law that a state must expressly consent to a rule (by, for example, signing a treaty) before it can be legally bound by the rule. Customary international law not only upsets this idea of consent, it does it by stealth. [11]

The International Court of Justice

The Statute of the International Court of Justice acknowledges the existence of customary international law in Article 38(1)(b), incorporated into the United Nations Charter by Article 92: "The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall custom, as evidence of a general practice accepted as law."

Customary international law "... consists of rules of law derived from the consistent conduct of States acting out of the belief that the law required them to act that way." [12] It follows that customary international law can be discerned by a "widespread repetition by States of similar international acts over time (State practice); Acts must occur out of sense of obligation ( opinio juris ); Acts must be taken by a significant number of States and not be rejected by a significant number of States." [13] A marker of customary international law is consensus among states exhibited both by widespread conduct and a discernible sense of obligation.

The two essential elements of customary international law are state practice and opinio juris , as confirmed by the International Court of Justice in the Legality of the Threat or Use of Nuclear Weapons. [14]

In relation to the psychological element that is opinio juris, the International Court of Justice further held in North Sea Continental Shelf, that "not only must the acts concerned amount to a settle practice, but they must also be such, or be carried out in such a way, as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it... The States concerned must therefore feel that they are conforming to what amounts to a legal obligation.". [15] The Court emphasised the need to prove a "sense of legal duty" as distinct from "acts motivated by considerations of courtesy, convenience or tradition". [16] This was subsequently confirmed in Nicaragua v. United States of America. [17]

Bilateral versus multilateral customary international law

The recognition of different customary laws can range from simple bilateral recognition of customary laws to worldwide multilateral recognition. Regional customs can become customary international law in their respective regions, but do not become customary international law for nations outside the region. The existence of bilateral customary law was recognized by the International Court of Justice in the Right of Passage Over Indian Territory case between Portugal and India, in which the court found "no reason why long continued practice between the two states accepted by them as regulating their relations should not form the basis of mutual rights and obligations between the two states." [18]

Other customary international laws

Other examples accepted or claimed as customary international law include the principle of non-refoulement and immunity of visiting foreign heads of state. United Nations Security Council in 1993 adopted Geneva conventions as customary international law because since the time being it has transformed itself into customary international law. If any treaty or law has been called as customary international law then parties which have not ratified said treaty will be bound to observe its provisions in good faith. [19]

See also

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  1. See Evidence of State practice Archived 2008-12-26 at the Wayback Machine .
  2. "Statute of the International Court of Justice" . Retrieved 30 May 2012.
  3. Yoram Dinstein. 2004. The Conduct of Hostilities under the Law of International Armed Conflict, pp. 5. Cambridge: Cambridge University Press.
  4. Władysław Czapliński. Jus Cogens and the Law of Treaties. In C.Tomuschat and J.M. Thouvenin (eds). 2006. The Fundamental Rules of the International Legal Order, pp. 83-98. Netherlands: Koninklijke Brill NV
  5. Article 53 of the Vienna Conventions on the Law of Treaties (1969)
  6. M. Cherif Bassiouni.1998. International Crimes: jus cogens and Obligatio Erga Omnes, Law & Contemporary Problems, 59: 63-74
  7. "Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I)". 8 June 1977. Retrieved 30 May 2012.
  8. Yoram Dinstein. 2004. The Conduct of Hostilities under the Law of International Armed Conflict, pp. 6-7. Cambridge: Cambridge University Press.
  9. Fisheries Case (United Kingdom v Norway) (Judgement) [1951] ICJ Rep 116, 131 where it is stated '…the ten-mile rule would appear to be inapplicable as against Norway inasmuch as she has always opposed any attempt to apply it to the Norwegian coast.' The case can be found at:
  10. citation needed
  11. Dinesh, Singh Rawat. "Know Customary International Law" (Online). ABC Live. ABC Live. Retrieved 30 April 2017.
  12. Rosenne, Practice and Methods of International Law, p. 55.
  13. "Customary International Law".
  14. "Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, I.C.J. Reports" 1996, p. 226, 253, [64],
  15. North Sea Continental Shelf, Judgment, I.C.J. Reports 1969, pp. 3, 43, [74],
  16. Ibid.
  17. Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United States of America), Merits, Judgment, I.C.J. Reports 1986, pp. 14, 98, [186],
  18. "Right of Passage over Indian Territory (Merits) (Port. v. India), 1960 I.C.J. 6 (Apr. 12)".
  19. Certain Norwegian Loans (France v Norway) (Jurisdiction) [1957] ICJ Rep 9, 53.