Panel 4.2 / Domestic Courts’ Lessons on the Theory and Interpretation of CIL

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4.2.1 / Cedric Ryngaert
From Customary Law Ascertainment to Interpretation: the Role of Domestic Courts

The TRICI project observes that ‘in the study of customary international law (CIL) there is a critical gap in understanding how customary international law (CIL) can be applied in individual cases once it has been formed’. The project then sets for itself the goal to uncover rules of interpretation of customary international law. In the words of the project, if such rules were to exist, CIL need not be induced each and every time, by reference to state practice and opinio juris, or asserted by judges. Such a goal appears to be at loggerheads with the very nature of CIL as a flexible and protean source of international law, that is at least potentially in a state of constant flux.

Given these characteristics, judges always have to revisit the very existence of customary norms de novo. Although unlikely, it is after all not impossible that customary norms form almost overnight (instant custom). Methodologically speaking, judges have to concern themselves first and foremost with the ascertainment and identification of norms of customary international law, before they can apply and interpret such norms. This follows from the very text of Article 38(1)(b) of the ICJ Statute, which provides that the ICJ (and courts more generally one may well posit) ‘shall apply’ … ‘international custom, as evidence of a general practice accepted as law’. Pursuant to this provision, courts can only apply a customary norm after they have first established its evidence-based existence. This process is admittedly interpretative, but it is so only in an evidentiary rather than normative sense. Instead of interpreting previously crystallized norms by analogy with Article 31-32 VCLT, judges interpret evidentiary materials placed before them, with the aim of distilling, or not, customary norms from those materials.

A look at the practice of courts reveals that they do not usually engage in thorough processes of customary international law-identification, however. This applies in particular to domestic courts, which either have little customary international law expertise, or which deal with cases in which the customary international law question does not occupy a central place in the dispute. This paper demonstrates empirically that domestic courts often apply rather than ascertain customary international law. They tend to rely on, and defer to other authorities (e.g., the ICJ, the ILC), even if occasionally they embark on a serious law-ascertainment process of their own. While such ‘other authorities’ only have evidentiary value that should be weighted with other materials evidencing (or not) the existence of a particular customary norm, one cannot escape the impression that domestic courts are simply giving effect to, or applying pre-existing customary norms. If that is true, there is in principle room for the development of rules of interpretation. The fact remains, however, that domestic courts continue to hew to the fiction that they are law-finders rather than law-appliers; accordingly, none of them has relied on or developed such rules. It is only if they own up to their limited agency in identifying customary law, that rules of interpretation can appear on the horizon.

4.2.2 / Luigi Crema
Once You Reach the Top of a Positivized Legal System, Customary Law Emerges Again. Hints from the Italian Constitutional Court

In general, the Italian constitutional legal system denies any status to customary law within Italian law. The only customary rules mentioned in the constitutional system are those of international law, which are incorporated into the Constitution through Article 10(1): “The Italian legal system shall conform to the generally recognized principles of international law”. This structure comes from the traditional, positivistic preference for written and codified rules, adjusted to meet the need to curb the Nation State from the possible excesses which historically led to fascism and WWII, by enlarging the sources of law above and beyond the Constitution.

The Italian Constitutional Court has often being asked to adjudicate on Art. 10(1) in generic terms, or by reference to specific treaties – including the ECHR and the UDHR. On almost every such occasion, the Court has refused to consider treaties as included under Article 10, and, therefore, it has never ruled on the difficult relationship between written law and customary rules crystalized, codified in an international treaty. Only in one case did it deal with written international law and customary rules together. In that case, the Court made generic references to several international treaties expressing, in the Court’s view, a certain “principle of international law”, without investigating its actual customary nature. More recently the Court referred to jus cogens and state immunities, but, again, without engaging in an analysis of state practice.

In addition to these cases dedicated to customary international law, the Court has heard a few cases in which it has had to adjudicate on the existence of constitutional customary rules among domestic State organs. It refrained, however, from reflecting on, or drawing, a precise theory concerning them and their place in the theory of sources. While customary law rules have an important position in international law and law in general, the Italian Constitutional Court still appears to have some difficulty accepting its role and handling it. This presentation will be both the occasion to present the Italian case law on customary international law, and to reflect on the importance of customary international law even in a legal system that relies only on written law.

4.2.3 / Gerard Hoogers
Customary International Law as a Tool for Federal Dispute Settlement: The Surprising Relevance of Customary International Law for the Domestic Legal Order in Germany and Austria

The publication of Triepel’s Völkerrecht und Landesrecht (1899) was a milestone in the development of international legal theory. It was also a very important contribution to the intellectual debate in Germany and the German-speaking world on the relationship between international and national law. In both the German Reich and in Austria Triepel’s work played an important role in the development of the dualist and transformist approach still dominant today. As a result of this, both the German Constitution of 1919 (the Reichsverfassung) and the Austrian Constitution of 1920 (the BundesVerfassungsgesetz) contain a paragraph dealing with the internal position of customary international law (art. 4 RV and art. 9 B-VG respectively). The Staatsgerichtshof für das Deutsche Reich (RStGH), the specialised court introduced by the 1919 Constitution to deal with federal disputes decided a number of interesting cases concerning disputes between two or more States in Germany by using a number of customary international norms incorporated through article 4 of the Constitution. In my presentation, I will analyse these decisions to see how and why the RStGH used these norms to settle conflicts of a domestic nature and how they were interpreted to be useful in a purely domestic context. The post-war German Constitution, the Grundgesetz, has an almost identical article to article 4 of the 1919 Constitution, article 25 GG. The main difference is that article 25 strengthens the domestic position of customary international norms by granting them prevalence over federal acts. Surprisingly however, the Bundesverfassungsgericht (BVerfG) refuses to acknowledge the relevance of customary international law for the settlement of federal disputes. Instead, it opts for the formulation of unwritten principles seen as of domestic origin that are materially identical to the norms used antebellum by the RStGH. My analysis will focus on the question what, if anything, has changed by this different approach. The analysis on Germany will be complimented by a short excurse to Austria to see if and how the Verfassungsgerichtshof (VfGH) uses article 9 B-VG to settle disputes between two or more Austrian states and if this approach differs from the German one. Thus, my presentation will shed light on the question whether and how customary international law can be a useful tool for purely domestic legal disputes.

4.2.4 / Nina Mileva
Old, New, Borrowed, or Blue: How can we Learn from the Interpretive Practices of Domestic Courts?

The interaction between domestic and international law is a dynamic relationship which has received renewed scholarly interest in the past decade. In the traditional conceptualization of domestic v. international law, the two levels interact in broadly two ways: i) the ‘monist v. dualist’ framework for the purpose of conceptualizing international law’s domestic application, and ii) the ‘sources of international law’ framework for the purpose of conceptualizing domestic law’s role in the international legal sphere. In the latter in particular, domestic law and legal practices may feature internationally through the mediums of customary international law (CIL) or general principles.

More interestingly however, scholars and practitioners are increasingly recognizing that the domestic and international levels interact in a much wider and more diverse manner than the one provided for in the traditional frameworks. Studies of the International Law Association (ILA) have shown that domestic courts engage with international law in significantly more diverse manners beyond the ‘monist v. dualist’ framework and the traditional framework of sources. On the other hand, domestic legal principles and approaches have also found their way into multiple fora of both international adjudication and international law making. Thus, it has been observed that the interaction between the two levels also implies mutual influence.

This paper will examine the relationship between domestic and international law with a particular focus on CIL and the rules for its interpretation. More specifically, the objective is to explore how domestic interpretive practices have influenced interpretation on the international level, and how they may inform or otherwise influence the development of rules for the interpretation of CIL. Bearing this objective in mind, the paper will examine the interaction between domestic and international law, with a view to developing a theoretical framework which captures the ways in which international law receives or learns from domestic legal practices in the field of CIL. In particular, the paper will focus on answering the question “how can international law learn from the interpretive practices of domestic courts?”. Thus, the paper will develop a working theoretical framework of interaction aimed at capturing the ways in which international law may learn from domestic law and practices with respect to CIL interpretation. This framework will serve as the basis for further research on the topic.

The paper will examine theoretical frameworks of interaction developed by several authors in the fields of general international law, international economic law, and environmental law. Then, building on these findings, the paper will turn to developing a working theoretical framework tailored to the interaction between domestic and international law specifically with respect to interpretive practices. The result will be a working theoretical framework which maps the ways in which international law can learn from the interpretive practices of domestic courts, for the purpose of developing rules for CIL interpretation on the international level.