Introduction
In order to fully grasp ‘the sources of international law’, perhaps a definition of international law itself is warranted. International law in general was systematically developed for the promulgation of international humanitarian law post World War II.[1] It is a system of rules, norms, and standards that apply between sovereign states and international actors.[2] There are marked differences between international law and domestic law. For international law, the lawmakers are of a collective nature, that is, states and international organizations, whereas the lawmakers of national law are individuals; selected through democratic process or otherwise. National law is primarily legislative, whereas international law enjoys a plurality of equivalent sources. Finally, international law is both vertically and horizontally pluralistic, the former referring to the lack of hierarchy among legal sources, and the latter is with reference to how different it is in different legal regimes. Contrastingly, national law enjoys both centralization and a hierarchy among sources. [3]
‘Source of law’ can be defined as facts or events that lead to the creation, modification, and annulment of valid legal norms.[4] With regarded to international law, they may be described as ‘the categories of rules of international law that are regarded as legally valid and binding.’[5] They define the rules of the system; new rules are accepted as a part of international law when they are attested by one or more sources of international law.[6] In simpler terms, it is a definite method of determining what the law is.[7]
The generally uncontested and formally accepted international law sources are as listed under Article 38 of the ICJ statute.[8] The four sources of international law listed are,
- International treaties,
- International customs,
- General principles and
- Judicial decisions
Although, it is up to the states themselves to decide what actually constitutes international law.[9] Further, as mentioned previously, there is no hierarchy among the listed sources, but sometimes, written obligations like treaties and judicial decisions are privileged over unwritten obligations like customs and general principles, mostly for evidentiary reasons. [10] There is a distinction to be made between formal and material sources of law. Formal sources are the methods for the creation of rules of general application which are binding on their addressee. Material sources act as evidence for the existence of a rule.[11] Peremptory norms of international law (jus cogens) may in principle, be considered to be placed higher than other norms, with reference to Art. 53 of the Vienna Convention on the Law of Treaties[12] and Art. 50 of the International Law Commission’s Articles on the Responsibility of States for Internationally Wrongful Acts,[13] although it is currently a debatable position.
Sources of international law
1. International treaties
Under Para 1 of Article 38 of ICJ [14], international treaties were defined as being general or particular, establishing rules recognised by the contesting States Parties to a dispute before the Court. They are written bilateral or multilateral treaties between states or international organisations, ranging from agreements, conventions, protocols to covenants.[15] Treaties are the most important source of obligation in international law.[16] Bilateral treaties may provide evidence of customary rules.[17] International treaties are drafted and adopted with the consent of participating parties.[18] It’s effect and significance is usually expressed in the principle ‘Pacta sunt servanda’ (agreements must be kept). The treaties are binding, and obligations must be performed in good faith.[19] The obligations created under treaties can be said to be quasi-contractual.
Many treaties like UNCLOS (Law of the Sea Convention) and human rights conventions, have almost universal participation, hence their character can be described as being more normative.[20] It has been suggested that treaties are to be understood as a source of obligation, and the rule of law concerning them is simply that the basic principles of the treaties have to be followed.[21] There is a distinction to be made with regard to ‘law-making treaties’ and other treaties, the former creates logical obligations which cannot be discharged by following it once. As opposed to treaties for the joint carrying out of a single enterprise, which will be discharged once fulfilled. Law-making treaties are framed as legal propositions, they create general norms to govern the conduct of parties.[22] Examples include the Geneva Conventions (1949), Hague Conventions(1899 & 1907), the Genocide Convention (1948) etc.
2. Customary international law
Under Article 38, customary international law is regarded as evidence of a general practice accepted as law, or put another way, ‘it is the generalization of the practice of states’.[23] It is a series of unwritten rules through which states conduct their relations with each other; customary law helped in the constitution of international law before the advent of the United Nations.[24] These rules are created by or can be inferred from the practice of states.[25] Practices carried out of courtesy cannot be claimed to be legal requirements. The particular rules of comity that are maintained without reservation, tend to develop into customary law.[26]
The distinction between customary law and treaty laws is that the former is binding on all states without exception, whereas treaties are applicable only to those who are party to it. [27] However, the question remains, what exactly constitutes ‘state practice’. This refers to sufficient instances of consistent following of an alleged custom, backed by ‘opinio juris sive necessitates’ (an opinion of law or necessity).[28] The elements of custom are:
1) Duration and consistency of practice– the requirement is of substantial uniformity; complete uniformity is not necessitated.[29] No particular duration is necessary once generality and consistency of practice are established.
2) Generality of practice– this deals with the difficulty in distinguishing between mere abstention from protest by states in the face of practice followed by others. Silence could mean agreement, but it could also be a denotation of a lack of interest.[30]
3) Opiono juris sive necessitatis (the psychological factor)– this is a contentious element, as some writers do not consider it an apt requirement for custom,[31] though it is conceded that something akin to it is necessary.
The ICJ proclaimed thus in the North Sea Continental Shelf cases,
“Not only must the acts concerned amount to a settled 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 need for such a belief, i.e, the existence of a subjective element, is implicit in the very notion of the opinio juris sive necessitatis. The States concerned must therefore feel that they are conforming to what amounts to a legal obligation. The frequency, or even habitual character of the acts is not in itself enough. There are many international acts, e.g., in the field of ceremonial and protocol, which are performed almost invariably, but which are motivated only by considerations of courtesy, convenience or tradition, and not by any sense of legal duty.” [32]
Examples of international customs include diplomatic correspondence, policy statements, official manuals, state legislation, international and national decisions etc.[33]
3. General principles
Described by Article 38 as the general principles of law recognised by civilized nations. These are the principles embedded in a legal system that are used to make sense of the different legal rules, with regards to their interpretation, application, how they relate to one another etc. International courts regard them as either interpretative tools, or autonomous sources of concrete obligations.[34] As per Dworkin, laws are not made of rules alone, they also contain principles, which are not specific to cases nor automatic in their operation, they may even conflict with each other.[35]The existence of these principles are necessary because laws cannot be made to cover every possible situation, principles will thus act as a higher authority in such instances. According to Oppenheim,
‘The intention is to authorize the court to apply the general principles of municipal jurisprudence, in particular of private law, insofar as they are applicable to relations of States.’[36]
General principles are formulated abstractly, and are wide ranging, they are used as a guide to interpret treaties and resolve conflicts between them. [37] Examples of general principles include the doctrines of good faith, equity, acquiescence, and estoppel.
4. Judicial decisions
These are considered auxiliary or ancillary sources. It includes judicial decisions and teachings of the most highly qualified publicists of the various nations, as a subsidiary means for the determination of rules of law, subject to the provisions of Article 59 of the Statute (The decision of the Court has no binding force except between the parties and in respect of that particular case).[38] They formally serve as means for the determination of legal rights and obligations. They are given weight because international courts apply international law, hence, their judgements logically indicate the existence of international law on given points. Further, judgements aid in the development of international law and may be the starting point of new customary laws in this regard.[39]
Some other material sources of international law include conclusions of international conferences, resolutions of the General Assembly, the teachings of eminent publicists, codification, and the work of the international law commission. Notions of equity, humanity and ‘legitimate interests’ are also considerations applicable to judicial reasoning. [40]
Conclusion
The sources of International law are what intimate its existence and give it its legitimacy. The four generally accepted sources of international law are International treaties, International customs, General principles, and Judicial decisions. With regards to international treaties, they are the most important source of international law. They are obligations created through an agreement of mutual consent, like covenants, protocols etc. Some treaties have a normative character and can prescribe the conduct of parties; treaties may also act as evidence for the existence of certain customary rules. Secondly, international customs, they are determined by state practice that is general and consistent, backed by ‘opinio juris sive necessitates’. They give the international law system some amount of structure and centralization. General principles are principles of law recognised by civil societies. It allows judges to make use of private law in their judicial determinations. They are wide and abstract; they can be used as interpretive tools or as distinct sources of legal obligations in themselves. Finally, judicial decisions act as ancillary sources, they evidence the existence of international law on certain given points. They may also lead to the creation of new international customary laws. They are ancillary sources because international courts do not follow the doctrine of precedents, in that, they are only binding on the parties to the dispute. Regardless, they are an indispensable source of expert opinion and legal reasoning. Altogether these sources of law are the primary references used to determine the content of international law, and the different obligations that arise under it.
Bibliography
Statutes and Conventions
Statute of the International Court of Justice (1946)
Vienna Convention on the Law of Treaties, UKTS (1980)
General Assembly resolution 56/83 of 12 December 2001
Case law
Fisheries (UK v Norway), ICJ Reports 1951 p 116
North Sea Continental Shelf, Judgement [1969] ICJ Rep 44
Books
Besson S and Tasioulas J (eds.), The Philosophy of International Law (OUP, 2010) Chapter 7
Brownlie I, Principles of Public International Law 7th ed. (OUP 2008) 6
Cf Kelson, Principles of International Law (2nd ed, 1967)
Corten and Klein, The Vienna Conventions on the Law of Treaties (2011)
Crawford J, Brownlie’s Principles of Public International Law 9th edition (OUP 2019)
Fitzmaurice G, Some Problems Regarding the Formal Sources of International Law (Brill 2020) 475-496
Higgins R, Problems and Process: International Law and how we use it (OUP 1994)
Koskenniemi M, Sources of International Law (Taylor & Francis 2017)
R Dworkin, Is Law a System of Rules (OUP 1977)
1 Oppenheim, para 12
Silverburg S. International Law: Contemporary Issues and Future Developments. (Taylor &Francis 2018.)
Shaw M, International Law (CUP, 8th ed, 2017)
Thirlway H, The Sources of International Law (OUP 2014)
Journals
Dingle L, ‘Legal Information Management’, 9 (CUP 2009), 273–283
Hernandez G, Sources of international law, Overview Article (2014)
Marmor A, ‘The Nature of Law’ (Stanford Encyclopedia of Philosophy 2008)
Malcolm S. “International law”. Encyclopedia Britannica, 13 Nov. 2019 <https://www.britannica.com/topic/international-law>
Simma B, “From Bilateralism to Community Interest” (1997) 250 Recueil des Cours de l’Académie de droit international deLa Haye 229
SS Wimbledon (1923) PCIJ Ser A No. 1, 25.
[1] Sanford Silverburg. International Law: Contemporary Issues and Future Developments. (Taylor &Francis 2018.).
[2] Shaw, Malcolm. “International law”. Encyclopedia Britannica, 13 Nov. 2019, <https://www.britannica.com/topic/international-law>. Accessed 19 April 2021.
[3] S. Besson and J. Tasioulas (eds.), The Philosophy of International Law (OUP, 2010) Chapter 7, 164-6.
[4] Andrei Marmor, ‘The Nature of Law’ (Stanford Encyclopedia of Philosophy 2008).
[5] Gleider I Hernandez, Sources of international law, Overview Article (2014)
[6] James Crawford, Brownlie’s Principles of Public International Law 9th edition (OUP 2019).
[7] Malcolm N Shaw, International Law 8th ed (CUP, 2017) 51-91.
[8] Statute of the International Court of Justice (1946) Article 38
[9] R. Higgins, Problems and Process: International Law and how we use it (OUP, 1994)
[10] LBID Gleider n (5)
[11] LBID Crawford n (6)
[12] Vienna Convention on the Law of Treaties, UKTS (1980) 58
[13] General Assembly resolution 56/83 of 12 December 2001
[14] LBID ICJ n (7)
[15] Lesley Dingle, ‘Legal Information Management, 9 (CUP 2009), 273–283.
[16] Corten and Klein, The Vienna Conventions on the Law of Treaties (2011)
[17] SS Wimbledon (1923) PCIJ Ser A No. 1, 25.
[18] LBID Gleider n (5)
[19] Hugh Thirlway, The Sources of International Law (OUP 2014) 31.
[20] B.Simma, “From Bilateralism to Community Interest” (1997) 250 Recueil des Cours de l’Académie de droit international deLa Haye 229, 335.
[21]Gerald Fitzmaurice, Some Problems Regarding the Formal Sources of International Law (Brill, 2020) 475-496.
[22] LBID Crawford n (5)
[23] Fisheries (UK v Norway), ICJ Reports 1951 p 116, 191
[24] LBID Gleider n (5)
[25] Martti Koskenniemi, Sources of International Law (Taylor & Francis 2017) 251.
[26] LBID Crawford n (5)
[27] LBID Hugh n (13).
[28] LBID.
[29] LBID Crawford n (5)
[30] LBID Crawford
[31] Cf Kelson, Principles of International Law (2nd ed, 1967) 450-1.
[32] North Sea Continental Shelf, Judgement [1969] ICJ Rep 44, para 77.
[33] Brownlie I, Principles of Public International Law 7th ed. (OUP 2008) 6.
[34] LBID Gleider n (5).
[35] R Dworkin, Is Law a System of Rules (OUP 1977).
[36] 1 Oppenheim, para 12
[37] LBID Gleider n (5).
[38] LBID ICJ n (7)
[39] Statute of the International Court of Justice (1946) Article 59.
[40] Lbid Crawford n (5)
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