CYIL vol. 8 (2017)

SANDRA BROŽOVÁ CYIL 8 ȍ2017Ȏ Court of International Justice, active in the interwar period. The above mentioned Art. 38, one of the provisions adopted from the PCIJ Statute, became one of the most cited provisions of international documents, both in doctrine and the case law of international courts and arbitral tribunals. In the period where both these Statutes were drafted, in the first half of the 20th century, the international custom “as evidence of a general practice accepted as law” was by far the most important and also the most numerous source of international law. On the occasion of negotiating the PCIJ Statute, the Delegate of the Kingdom of Belgium, Baron Édouard Descamps, mentioned that custom had always had a key role in international law (“law of nations,” “ ius gentium ”), because this system is lacking any central legislative power. The treaty relations between states and rights and duties stemming directly from treaty provisions were still not really developed at this time. 1 Customs prevailed quantitatively. The inclusion of custom into the list of sources examined by the PCIJ during its decision-making activity was generally accepted and there was no tough debate on this issue among the delegations. 2 Traditionally, public international law is defined as a legal system of rules setting the rights and duties of States in their mutual relations, because states were considered as only subjects of international law for a long time. At the beginning of the 20th century, it was emphasised that the rules of the international community originate from customs and usage and they are only occasionally given precision by treaties concluded between two or more states or by decisions of arbitral tribunals or courts of sovereign states (e.g. national courts). 3 International courts in today’s meaning were not yet numerous and the PCIJ was perceived as an equivalent to an arbitral tribunal. Concerning the fact that international law is a completely different system than municipal law, certain issues viewed as specialities by the internationalists can be seen as a critique of systematic deficiencies from the municipal law viewpoint. This is the case for customs and their key importance in international law if they are confronted with the rule of law standards applicable at the municipal law level. A crucial part of these standards is represented by legal certainty and the connected possibility to access the exact normative content of the binding rules in order to understand it. 4 These requirements are obviously not met by custom, because often it is not clear whether the specific custom exists and what the rule enshrined therein is. The customary norm needs to be identified, interpreted; the sense and content of the rule should be properly analysed. We can conclude that custom does not need to fulfil the rule of law requirements, insofar as it regulates the behaviour of states and international organizations as international law subjects and does not interfere with constitutionally guaranteed rights 1 TOMKA, Peter, The Judge and International Custom , Conference Proceedings, statement delivered in Paris on 21 September 2012 at the conference “The Judge and International Custom”, organized by the Ministry of Foreign Affairs of France and the Committee of Legal Advisers on Public International Law (CAHDI) of the Council of Europe, p. 7 [on-line] [accessed 4 May 2017] . 2 Ibid. 3 It was mentioned in a lecture at Cornell University in the city of Ithaca in the state of New York (USA) on 24 March 1926. Published in: WICKERSHAM, George, W., Codification of International Law in Geneva, The Cornell Law Quarterly , Vol. 11, 4/1926, p. 439. 4 MLSNA, P., KNĚŽÍNEK, J., Mezinárodní smlouvy v českém právu (Treaties in the Czech Law) , Linde, Prague, 2009, p. 45.

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