The practice of public international law at NATO 'Supreme Headquarters' (SHAPE)

The chapter offers a window into the work of the Legal Adviser and Office of Legal Affairs (ACO OLA) of the Supreme Headquarters Allied Powers Europe (SHAPE), Allied Command Operations (ACO). The Adviser is responsible for providing independent military and institutional legal advice to the Supreme Allied Commander Europe (SACEUR) and is based in Mons (Belgium). The chapter opens by offering a historical background of NATO, as an international organization and an alliance, providing information on NATO’s complex and challenging institutionalization and sui generis, decentralized institutional makeup: delineating ‘the Organization’ (NATO HQ) from the two ‘Supreme Headquarters’ (one of these being SHAPE) and these international organizations from other NATO bodies, headquarters, units, etc. The chapter also offers a brief history of SHAPE, including its position in international law, before turning to an analysis of the ACO OLA: its mandate; functions; areas of activity; its contribution to NATO and SHAPE functions and operations through its International Law, Operational Law, and Legal Management Branches; and its contribution to the development of NATO’s legal acquis and public international law. Finally, the piece considers the institutional and operational law challenges that face ACO OLA, concluding that its institutional challenges are similar to those of other international organizations, but its operational challenges are more unique. The most prominent of these involve grey zone/hybrid warfare, lawfare, and legal domain; rules of engagement; and detention in non-international armed conflict.