This book conceptualizes the accountability deficit of missions engaged in the international administration of territories. In so doing, a public-law approach is adopted. The book explores to what extent it is warranted to perceive these missions as public entities exercising public power rather than international organizations merely engaged in extensive peacekeeping and, if such a paradigm shift is accepted, how public law influences our understanding of the accountability deficit. The linkage is explored between the rule of law, judicial review and an independent judiciary as cornerstone-principles of public law on the one hand and the main institutional and conceptual characteristics of international territorial administration on the other hand. The author concludes that insufficient regard for public law principles is at the core of the accountability deficit and that public law should play a role in addressing this deficit. This book is of interest to both international and constitutional lawyers, as well as practitioners engaged with international organizations and their subsidiary field missions.