CYIL vol. 8 (2017)

CYIL 8 ȍ2017Ȏ THE IMPORTANCE OF CUSTOMARY LAW FOR THE CODIFICATION OF THE LAW … THE IMPORTANCE OF CUSTOMARY LAW FOR THE CODIFICATION OF THE LAW OF TREATIES Sandra Brožová Abstract: The purpose of this contribution is to capture the customary nature of codified rules governing interpretation of treaties. The paper looks into history and recalls the importance of customary law in the times when the rules of treaty interpretation emerged. The fundamental case law of ICJ is further analyzed. The contribution also focuses on the Vienna Convention on the Law of Treaties (VCLT), codification under the auspices of International Law Commission and its predecessors. The similarity of interpretative methods used before and after codification is considered as a proof of their customary character, together with settled doctrinal opinions. Despite many differences, treaties and custom as principal international law sources still have significant common features. Resumé: Cílem příspěvku je vystihnout obyčejovou povahu kodifikovaných pravidel vý- kladu mezinárodních smluv. Pohled do historie poukazuje na klíčový význam obyčejového práva v dobách, kdy se výkladová pravidla utvářela. Dále je analyzována nejdůležitější ju- dikatura MSD k této otázce. Příspěvek se také zaměří na Vídeňskou úmluvu o smluvním právu, její kodifikaci na půdě Komise pro mezinárodní právo a její předchůdce. Podobnost výkladových metod používaných v době před a po kodifikaci je považována za důkaz jejich obyčejového charakteru, podpořený ustálenými doktrinálními názory. Navzdory některým rozdílům mají mezinárodní smlouvy a obyčeje jako nejdůležitější prameny mezinárodního práva stále významné sdílené prvky. Key words: treaty interpretation, customary law, codification, sources of international law, ICJ (International Court of Justice), UN ILC (United Nations International Law Commission). On the Author: Sandra Brožová was born in 1990 and graduated from the Faculty of Law, Charles University in Prague (JUDr. in 2014 and Ph.D. in 2017). Alongside studies, she gained professional experience in public administration both on the national and international level. She is interested in international public law, with focus on treaty interpretation, codification, international organizations, multinational corporations and responsibility. The purpose of this article is to capture and describe the relevance and importance of customary law for the creation and establishment of settled international legal regulative framework for treaties, with special focus on the genesis of rules of treaty interpretation. The following and related aim is to grasp the reasoning in favour of their customary nature. Custom and the Treaty as Sources of International Law Although no generally valid, legally binding and exhaustive delimitation of public international law sources exists, the Art. 38 of the Statute of the International Court of Justice is standardly accepted as their authoritative overview. This provision contains the list of sources that the ICJ takes into account while deciding contentious cases and rendering advisory opinions. In this context, it is useful to recall that the ICJ Statute, drafted shortly after the Second World War, took many provisions from its predecessor, the Statute of the Permanent 1.

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