w. IntroductionInternational LawInternationalrule is a set of rules established by custom or treaty which are recognised bystates and are considered as binding. Without such rules, the international arenawould be chaotic since there would be no governing law between states. Theserules serve as a framework which define states’responsibilities towards other states and within the boundaries of otherstates. Such rules comprise human rights, security and self-defence, crime,migration, war, sustainable development, world trade and other issues whicheffect the world.
These rules also serve as the basis of bilateral agreementsbetween one state and the other. Treaties are written as new needs arise on theinternational arena where states are party to such treaties on agreement andonce they agree to give the necessary consent to the contents of the agreement.A state binds itself to a treaty by signature, ratification, acceptance,approval and accession. The most important source of legal internationalobligations are treaties, having a direct influence on content of generalinternational law.
Treaties are generally defined by the Vienna Convention asbeing “an international agreementconcluded between States in written form and governed by international law,whether embodied in a single instrument or in two or more related instrumentsand whatever its particular designation”1. Customary International law, on theother hand, is also an important characteristic of international law which involves the principle of custom. It involves the longestablished practices or customs in any given country which are considered tobe legal and therefore considered as part of the law. Customary law is focused on theactual practice and opino juris of the states, i.e. the belief by states thattheir practice is legally required by the norm. Many scholars argue therequirement of opino juris since the ICJ never requests proof of opino juris toensure an established form of practice in any given state but it rather focuseson actual practice in a particular state which is part of the norm and whichnorm is accepted by the states, as per the 1985 Continental Shelf Case betweenLibya and Malta.
Article 39 (1)(B) of theStatute of the International Court of Justice ( ICJ) affirms that the court shall apply in additionto conventions ‘international custom, as evidence of a general practiceaccepted as law2. Nevertheless, states must believe thatthey must conform with the norm for customary law to be regarded as required bylaw. What this means is that for customary law to be considered as part of arequirement by law, states need to believe that the practice in itself islegal, part of the norm and a requirement by law.
International law, as a general rule, is set toestablish relations between states and to regulate their behaviour. It is thus pertinentthat customary law is addressed and acknowledged and given its due importance. Customary law, in simple terms, is any givenbehaviour by a state regarded as part of the norm.
Although States are expectedto conform to international law and conventions, whether and how customary lawis applied in a country should also be given its due importance. The consent ofstates who are party to conventions and international law should be obtained.It should be observed that states bind themselves to their own actions andpractices as regard this part of their customary law. In actual fact, customarylaw which consists of a set of unwritten rules, mostly emerge in cases oflacunae where treaties do not manage to regulate all aspects of internationallaw. The principle and importance of customary law isdifficult to explain yet it is a vital part of international law where togetherwith treaties and conventions complete international law in its entirety.
TheICJ is tasked to consider customary international law not only by the generalpractice accepted by law but also by what states have accepted as law. Therefore,opinio juris is subject to dispute but is also a legally binding practice. Ageneral practice, referred to as the objective element, because it is visibleand accepted by law.
These two elements have been juridically approved by theInternational Court of Justice.In fact, apart from the 1985 Libya Malta case, theInternational Court of Justice also considered these two elements, generalpractice and opinion juris, in the 1986 Nicaragua Judgement as the basis of theformation of customary law.Similarly, treaties areconsidered the strongest and most binding type of source of international lawbecause the countries that agree to and sign it are represented by it. Treatiesform international law by creating standards, agreements, and diplomatic tiesbetween states. Treaties are similar to contracts between countries.
States maydebate the interpretation or implementation of a treaty, but the writtenprovisions of a treaty are binding.3 The ‘Vienna Convention on the law of Treatiesof 1969’ is the main regulator which monitors treaties and is considered as the”treaty of treaties”.4 This convention gives aclear definition of a treaty and describes how treaties are made, amended,interpreted, how they operate and are terminated. The rights and obligations ofparties are described and outlines in specific treaties.5 Article 2 (1)(a) of theVCLT defines a treaty as “treaty means an international agreement concluded between States in writtenform and governed by international law, whether embodied in a single instrument or intwo or more related instruments and whatever its particular designation;”6 VCLT only relates totreaties that are governed by international law. Existing customary law iscodified by treaties which in return is binding on non- party states as well.
7Treaties could be a direct source of international law or reflective of acustomary or general principles of law as evidence. International treatiescould be law making treaties or treaty contracts.8The 1955 Nottebohm case which was decided by theInternational Court of Justice was an important and significant case where in the decision the judge declaredthat he would not be referring to the Bancroft treaties. The reason was thatthe judge considered these treaties as incorrect and “as constituting aprecedent”.
According to the judge the Bancroft treaties were only binding onthe contracting parties.9It was concluded that there was no international law pertinent to the Nottebohmcase.10It would unsafe to conclude conclusion that treaties are can cause precedentswhich are law binding on non-signatories.11This case is by no means an isolated example of such use of treaties.
Thereports of international tribunals often have reference to citations oftreaties introduced by parties as support for their contentions although theparties were not signatories of the treaties. For example Colombia cited anumber of extradition treaties in the Asylum case, which the ICJ foundinapposite for the question of diplomatic asylum without stating whether such treatieswere irrelevant as precedent.12Some courts have found that similar provisions in many extradition treatieshave been applicable to states which have not expressly accepted thosetreaties.
Treaties are expected to be executed in good faith,in keeping with the principle of pacta sunt servanda arguably the oldestprinciple of international law, and so treaties are sometimes described assources of obligation under law. Without this principle, which is explicitlymentioned in many agreements, treaties would be neither binding norenforceable.13The use of multilateral treaties increased dramatically as they have proved tobe an effective way to establish new rules of international law, particularlywhere there is a need to respond quickly to changing circumstances.14Article 38 of the Statuteof the International Court of Justice recognises a definitive statement of thesources of international law where it states; 1) the Court, whose function isto decide in accordance with international law such disputes as are submittedto it, shall apply: a) international conventions establishing rules recognizedby the contesting states; b) international custom; c) the general principles oflaw; d) subject to the provisions of article 59, judicial decisions and thewriting of most highly qualified publicists as subsidiary means for thedetermination of the rule of law; 2) the provision shall not prejudice thepower of the court to decide a case ex aequo et bono, if the parties agreethereto.15Thus it can be stated that treaties and custom areboth equally important and contribute to the making of international law. Allbranches of international law incorporate customary law and treaties. Treaties,protocols, conventions together with customary law which bind all states parties,make up international law.
16 Theeffectiveness of international law is much based on how treaties and customarylaw complement each other. It is important to note that treaties are an explicit source of law whichgains legitimacy through signatures while customary law is implicit throughgenerally accepted practises of nation states thus the importance of givingboth equal weight and to understand the importance of the basis of the formationof international law.17It can therefore be stated that customaryinternational law and treaties are both law making processeshowever the way treaties are formed differ to the way customary law is createdin that customary law is not supported by dispute resolution mechanisms anddoes not contain flexibility clauses as found in treaties.
Furthermore,Customary law applies to all states whilst treaties apply to those states whoconsent to it.18However the basic difference is always practice versus negotiation since theway treaties are created is always based on negotiation processes betweenstates whilst custom is formed through practice. Althoughcustomary law is formed by practice, it is important to note that in the caseof territorial sea disputes, states argue their position based on custom whilstother states respond by written agreements.
This is a clear picture of howcustom and treaties contribute to the coordination and position of states inagreement with the rest of the states. On one hand we have territorial seaclaims as ‘custom’ and on the other hand we have written disputes which areopen to negotiation and which eventually establish treaties, custom andpractice in a written solidified mannerTheNicaragua vs United States Case (1986)The Nicaragua vs United States Case (1986)concerned issues relating to military and paramilitary activities carried outby the US against Nicaragua between 1981 and 1984. Due to a multilateral treatyreservation, the court could not refer to the United Nations Charter .Therefore the court based its findings on customary law and the general principlesof indternal law since the issue concerned the use of force and self-defence.19In this particular case the court considered thefact that although custom may not be codified it still exists side by side totreaties and so both customary and treaty law should be applied. In a similar case, the North Sea Continental ShelfCases, the same argument was used in that the principles of customaryinternational should be considered as existing side by side treaty law and thattreaties do not necessarily or always supervene where customary law ceases toexist.
Reference was also made to Article 51 of the UNCharter which states that a treaty itself can recognise the existence ofcustomary international law with respect to the same subject matter. Forexample, the Court said that the term “inherent” in Article 51 recognisedthat customary law rights of self-defence existed alongside treaty provisions.20 Inthis case it was argued that when a state exercises the right of self-defenceunder Article 51, it also has an obligation to report the use of force to theSecurity Council. Thus it was declared by the court that this was a treatyrequirement which did not exist under customary law and so the United Stateswas not breaching customary law but was rather failing to proof that self-defencewas required since no report was submitted to the security council about thenecessity to use force as a means of self-defence.
Theinteresting argument in the Nicaragua vs United States case is that Article 51of the UN Charter does not define the term ‘armed attack’ and the concept ofnecessity and proportionality, whilst customary law does. The Court highlightedthis as proof that customary law does exist alongside treaty law and that thesources of law do not always overlap or have the same content. Furthermore Article 31 of the ViennaConvention on the Law of Treaties21specifically states that treaty law can be interpreted with the assistance ofcustomary law or general principles of international law. As regards the issue of opinio juris and state practice, the court didconsider these as essential and contributory factors to the formation ofcustomary practices. With regards to state practice, the court claimed thatcustom does not have to be consistent as inconsistency does not affect theexistence of the customary rule principle as long as it is not breached.
However,for a customary law rule to be formed state practice is always required. Incustomary international law, opinio juris is the second element necessary toestablish a legally binding custom. It denotes a subjective obligation, a senseon behalf of a state that it is bound to the law in question.22Article 38(1)(b) states that the custom to be applied must be “accepted as law”Australia v Japan:Whaling in the Antarctic (2014)Thetreaty concerning this case dated back to 1946 by the International Conventionfor the Regulation of Whaling. This was case where Australia accused Japan wasin breach of obligations under the 1946 International Convention for theRegulation of Whaling and of other international obligations for thepreservation of marine mammals and the marine environment23Inthis dispute the Court looked closely at the contents of the agreement and theinterpretation of provisions, particularly Paragraph 1 which states that states:”may grant to any of their nationals a special permit authorizing thatnational to kill, take and treat whales for purposes of scientific research”.Thus although treaties bind states by means of agreement in an attemptto bring about international order, disputes also arise and cases are presentedto the ICJ to assist with the correct interpretation of the contents of theagreement. ICJ is then tasked with delving into the text, interpreting it andadapting it to countries on a case by case basis.As perthe above two examples the relationship between treaty and custom is strong andis directly related to the importance of international law particularly with regardsto theory and practice.
Both exert an equal amount of influence on each otherand on legislators so that any issue rising on the international arena isaddressed using both theory and practice, and therefore both custom andagreements reached in treaties. Thus regulations presented by both equallycontribute to the body of international law and at times may also conflict eachother. The Vienna Convention makes reference of customary law which willcontinue to be regarded as equally important to treaties. Yet the contents ofthe Vienna Convention advocates the importance attributed to customary law. Treatyactivity can constitute state practice for the formation of a customary norm.One has to see whether states are only acting under their treaty obligations orwhether adherence to treaty obligations has grown to include opinio juris andbroader state practice.24An example is the UN Convention on law of high seas as a lot of UNCLOSprovisions have become customary international law. States which are not partof the UNCLOS are bound by some of the provisions of the convention.
25Therefore it is safe to say that for a treaty to create custom, you need nontreaty parties acting as if they are bound by the treaty. A treaty can be usedto contract out of a customary international law. There are however certainobligations that no state can contract out of such as the jus cogens normswhich are certain fundamental, overriding principles of international law, fromwhich no derogation is ever permitted.26Such examples include the prohibition on the use of force, the law of genocide,principle of racial non- discrimination, crimes against humanity and the rulesprohibiting trade in slaves or human trafficking.27Duringdisputes, custom and treaties are looked at first and formerly to evaluaterules in a given situation. As per thehumanitarian law case in former Yugoslavia, the ICJ identified the importanceof applying customary law which included the consideration of treaties such as theGeneva Conventions of 12 August 1949 for the Protection of War Victims, the Hague Convention (IV) Respecting the Lawsand Customs of War on Land and the Regulations , the Convention on thePrevention and Punishment of the Crime of Genocide of 9 December 1948 and theCharter of the International Military Tribunal of 8 August 1945. In this casethe court found it important to refer to customary law incorporated in theaforementioned treaties so as to reach a fair and amicable agreement.
As a final note on hierarchy and what shouldcome first, whether it is treaty or customary law it can be stated that althougha treaty can prevail over customary rule since it is a form of legal agreementbetween states, such treaty should not affect the rights of States not party tothat treaty. Therefore, there is no set hierarchy of norms in internationallaw. States can agree to deviate from customary law and enact treaties toenforce changes. In cases where a treaty conflicts with customary law, treatieswill prevail over customary rules which are not consistent.
In cases ofgenocide, torture and slavery treaties will prevail and enable other states tointervene and defend people. Therefore, there exists no strict hierarchybetween treaty and customary law.