Panos Merkouris

In international law interpretation is ubiquitous. However, whereas in the case of treaty interpretation, this process has been codified in Articles 31-33 of the Vienna Convention on the Law of Treaties, the interpretation of rules of customary international law has remained largely unexplored. This monograph demonstrates not only that rules of customary international law can be interpreted but also that they have continuously been interpreted by international and domestic courts. Through an examination of this case-law, the various methods of interpretation of customary rules and their limits are identified as well as the similarities and differences with the rules of treaty interpretation.

The law of treaties is in constant motion, understood not only as locomotion, but also as motion through time and as change. Thus, kinesis and stasis, two sides of the same concept of 'motion', are the central themes of Treaties in Motion. The concept of motion adopted in this book is based on the philosophy of Aristotle. He identified six types of motion: creation (genesis), increase (auxesis), diminution (meiosis), alteration (alloiosis), destruction (phthora), and change of place (kata topon metabole), which has been amended by the authors to change in space-time (kata topon kai chronon metavole) to reflect our modern scientific understanding of time as a dimension through which motion and change occurs. Each chapter's analysis proceeds by focusing on a specific area of a treaty's 'life-cycle', where each type of motion shines through and is described through three different frames of reference: treaties, the Vienna Convention of the Law of Treaties, and customary law.

In Article 31(3)(c) VCLT and the Principle of Systemic Integration: Normative Shadows in Plato’s Cave the author tackles a provision on treaty interpretation that has risen in prominence, Article 31(3)(c) VCLT. This article, which enshrines the principle of systemic integration, and its exact scope has become and continues to be a hotly debated subject in academic and judicial circles. Through an examination of both its written and unwritten elements, the author argues that the ‘proximity criterion’ is the optimal way of understanding and utilizing this provision, that conflict resolution principles may be of use within Article 31(3)(c) and finally, that the principle of systemic integration is indispensable not only for interpreting treaty provisions but customary international law as well.