Sources of international law

  • Created by: Nikki
  • Created on: 18-04-16 15:15


Art 38, Statute of the ICJ 

(1) The Court, whose function is to decide in accordance with itnernational law such disputes as are submitted to it, shall apply:
(a) International conventions, whether general or particular, establishing rules expressly recognised by the contesting states;
(b) International custom, as evidence of a general practice accepted as law;
(c) The general pricniples of law recognised by civilised nations;
(d) subject to provisions of Article 59, judicial decisions adn the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rule of law
(2) This provision shall not prejudice th epower of the Court to decide a case ex aequo et bono, if the parties agree thereto 

Sources of law:
- treaties (a)
- customary international law (b)
- general principles (c)

Other issues
- new sources of law?

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Sources of international law

Secondary rules are referrd to in international law as sources of international law --> less clearly defined than in municipal system

Material source --> the place (e.g. document) in which teh terms of the rule are set out 

Formal source --> determines the authority for the rule as a rule of law binding on States 
- identified in Art 38
- two most important sources are treaties and international custom
- example --> rule laid down in treaty = material and formal source; treaty rule applied to non-party State: material source = wording of original treaty, formal source: international custom

No satisfactory answer to what teritary rule determines identification of secondary rules --> realisitc answer = pacta sun servanda (what has been agreed to must be respected 

Doctrine of sources is subject to much criticism but it is the most workable method

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Treaties and conventions in force

  • basis for binding nature of treaties = pacta sunt servanda
    • 1969 VCLT (codification of pre-existing general law on teh subject), Art 26: 'Every treaty is binding upon the parties to it and must be performed by them in good faith' 
  • formal source of law --> created by agreement between states
  • 'law-making' treaties: multilateral conventions laying down for the parties to thema  whole regime 
  • parties commit to certain behaviour that would nto be legally required of them in absence of treaty 
    • jus dispositivum - rules of law from which States may freely contract out, by treaty
    • variation or exclusion only effective betwen the parties 
  • jus cogens --> cateogry composed of a limited number of norms which,b ecause of their importance in and to the international community, remain binding notwithstanding any agreement to the contrary (Arts 53, 64 VCLT)
  • State which is not party to a treaty is under no obligation (Art 34 VCLT)
    • 2 exceptions -->
      • (1) when a treaty oblgiation is or becomes an obligation of general customary law 
      • (2) when a third State accepts an obligation stated in the treaty or derives a benefit from the treaty 
  • where the treaty is a multilateral conventions of the 'law-making' type, it has been suggested that a State could, simply by conduct, indicate its acceptance of the regime of the convention as applicable to itself 
  • 'treaties and conventions in force' --> excluding treaties which have not, or not yet, come into force, or which ahve ceased to be binding on parties --> ratification as test of 'in force'
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Customary International Law (1)

  • legal oblgiations derived from legitiamte expectation created in others by conduct
  • 2 element theory -->
    • Established, widespread, consistent practice on part of States
    • Opinio juris sive necessitatis (opinion as to law or necessity)
  • State practice 
    •  not enough --> must be evidence of beleif that such practice is rendered oblgiatory by existence of a rule of law requiring ti (North Sea Continental Shelf case) 
    • Accumulation of instances of States asserting a right or objecting/refraining from objection constitutes overal practice required
    • action or inaction of States in relation to each other or in realtion to other recognised international actors 
    • need not be practice of every single State of the owrld, so long as it is widespread and consistent 
    • wide range of activities --> words alone can in some circ constitute state practice, but such words most often carry more weight when they are backed up by actions 
    • 3 criteria to assess sufficiency:
      • consistency --> Asylum case 'constant and unfirom' 
      • generality --> Anglo-Norwegian Firsheries 'generally adopted in the practice of states'
      • duration 
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Customary International Law (2)

  • Opinio juris
    • Difficulty of attributing a state of mind (OJ) to a state
    • if acts of practice are to be attributed to a motive other than the consciousness of conforming to a rule, they cannot show OJ
  • States that cannot participate in the practice --> 
    • more significance accorded to states with relevant attributes (Nuclear Weapons case - but this was controversial)
  • New subject matter, no state practice at all?
  • Theoretical difficulties of the process by which customary rules change and develop --> not a rigid and unchangeable system but in practice sometimes operates as such
  • If a claim is based on general CIL, sufficient to show that the rule exists, no need to show that the other party has accepted it
    • 2 exceptions
      • (1) alongside general customary law there are rules of special or local customary law 
        • apply only within a defined group of States
      • (2) persistent objector
        • generally accepted that a State which objected consistently to the applicaiton of a rule of law while it was still in process of becoming one could 'opt out' of the application of the rule even iafter it had acquired the status of CIL
  • not made simply by a majority --> rules can be blocked form coming into existence by a minority 
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General principles of law

Only relevant where issues are nto governed yb any treaty or there is no established rule of customary law to determine them

2 approaches

(1) principles derived from comparison of various systems of munificpal law 

(2) principles inherent in any system of law properly so called 
- e.g. pacta sunt servanda; procedural fairness
- minority view

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Subsidiary sources: judicial decisions and teachin

'subsidiary' --> if a rule of IL is stated in a judicial decision, it will be stated as a rule deriving either form treaty, custom or the general principles of law 

Material sources with a special degree of autohrity 

Officially they do not make law, they onlyhelp in identifying or declaring itnernational law the validity of which depends on some other source

No binding precendent in international law, not even decisions of ICJ 

Not limited to decisions of international courts and tribunals --> decision of municipal courts too --> useful statemetn of IL on a particular point; court as an organ of State so decision as State practice on a question of CIL

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Relationship between treaty and custom

Treaty may be used as practical evidence of state practice

If a treaty creates rights and oblgiations of non-customary nature but a number of States make a habit of concluding treaties containing certain standard provisions, may be evdence of recognition of the existence of a costume requiring them to do so
- but putting it in treaty may suggest lack of opinio juris

VCLT Art 38 - nothing precludes a rule in a treaty becoming a customary rule of international law, recognised as such

Where a cusomary rule has been replaced by a multilateral treaty the customary rule continues to exist, not only for non-parties to the treat but also for the parties to it 

3 situations where existence/creation of a customary rule might be relatd to treaty provisions (NSCS case)
(1) A treaty may embody already established rules of customary law: merely declaratory of such rules (codification)
(2) A multilateral treaty states rules and pricniples which can be found reflected in practice of States prior to the adoption of the treaty (crystallisation)
(3) Third States find it convenient to apply the convention rules in their mutual relations (helping to create custom)

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Hierarchy of sources

General rule = two principles
(1) lex specialis derogat generali (the special rule overrides the general rule)
(2) lex posterior derogat priori (the later rule overrides the earlier
- possibility in some difficulty applying these to custom 

General principles of law should provide a fall back sourc eof law in event taht no treat of CIL can be found to apply to given situation

Art 38 doesn't indicate whetehr there is a hierarchy betweeen custom and treaty 

Where a custom arises subsequently to conc of a treaty and which might be regarded as lex specialis in relation to the regime established by the treaty -->
- if new CIL is accepted as JC, according to Art 64 VCLT, the inconsistent treaty provision will be overriden and also 'any existing treaty which is in conflict with taht norm becomes void and terminates'
- if parties to treaty contributed to development of new CIL by acting inconsistently with treaty --> modificaiton of treaty in effect

If none or only some parties have participated in new CIL --> Art 41 VCLT: defines procedure for amendment of multilateral treaty between certain parties only --> no tacit agreement 

Existence of distinction between JC and jus dispositivum implies that a newly developed CIL which is not JC does not affect the operation of a pre-existing treaty --> but unsettled point

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Possible new or additional sources

(1) Unilateral acts 

(2) Equity

(3) UN GA resolutions

(4) The problem of superior norms (JC) 

Shari'ah law debate from Islamist jurists

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Art 38: focus on ideas as to sources of law following establishment of PCIJ - workable sstructure of recognised law-making processes


  • illogicality of rules as to creation and development of CIL --> difficulty of its application
  • multiplicity of legal or quasi-legal instruments governing state action --> ultimately treaty based but difficult o fit into traditional system of sources
  • suggested new approach

BUT, definition in Art 38 is likely to continue to guide international community and judges

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Application (1)

Refugee Protection: A guide to International Refugee Law' (UN High Commissioner for Refugees)

  • state pratice
  • convention/treaties
  • regional laws and standards
  • UNHCR Exec Committee conclusions
  • national laws and standards
  • international humanitarian law
  • national parliament decisions 
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