Air defense identification zone state practice and the progressive development of limited sovereign security rights over international airspace

Abstract

The People’s Republic of China (PRC) was portrayed as disruptor of the Air Defense Identification Zone (ADIZ) state practice when it established the East China Sea (ECS) ADIZ in 2013. The ECS ADIZ has drawn seemingly unwarranted negative international publicity as an outlier. It has also elicited renewed academic discussions as some scholars doubt the legal grounding of ADIZ while others opine that ADIZ – or at least the right of states to declare an ADIZ – has already become customary. The thesis principally examines whether the PRC’s participation in the ADIZ state practice signals the formation of a customary norm. It asserts that the creation of the ECS ADIZ constitutes a significant incremental contribution to the shaping of a progressive emergence of a norm on state sovereign security rights over international airspace contiguous to the territorial airspace. The thesis adopts a research design with a constructivist theoretical framework where states through their practice help shape and influence ADIZ formations and are in return influenced and shaped by them. This annular process takes place through a conversation between and among states with extraterritorial ADIZs and the international community at large. The thesis is primarily oriented to be doctrinal but informed by other methodologies and methods such as archival, quantitative, and qualitative research. The ADIZ state practice is close to becoming a customary norm. While the PRC’s participation in the ADIZ state practice is not an anomaly, such participation only indicates a significant incremental contribution to the progressive development of limited sovereign security rights over international airspace contiguous to the territorial airspace. Current international law, which confirms the existence of treaty law and customary rules, serves as a mediating authority on state attempts at extending jurisdictional control over international airspace. Nevertheless, there are existing customary rules and principles such as the right of self-defense that can arguably provide legal permissibility to the ECS ADIZ and ADIZs in general. When measured using the International Law Commission’s (ILC’s) two-constituent-element basic approach for identifying custom expressed in the draft conclusions on the identification of customary international law, the conduct of the 20 or so states with ADIZs including the PRC may pass the test of general practice. The ADIZ state practice can arguably be considered as sufficiently widespread and representative, and, notably, it has not been legally challenged by the international community. With respect to the second element of opinio juris when taken to mean acceptance as law of ADIZ as a legal obligation, the absence of objection does not unequivocally translate to implied consent as the primordial consideration of the safety of the aircraft and their passengers underpins the international tolerance. The thesis is probably the first scholarly work to apply the ILC’s legal framework to examine the legal status of ADIZ under customary international law. It is also the first to adopt the concept of indeterminate territory to analyze the legal status of the Spratly Islands and their airspace and the implications of indeterminacy on the legality of future ADIZs over the Spratlys. It departs from the US-oriented matrix by employing ADIZ case studies on a subregional basis to map out the possible legal outlines of ADIZs established over contested or disputed territories as well as those over international waters and undelimited non-territorial maritime domains.