Belligerent Occupation and Annexation in the International Legal Order

The aim of this thesis is to analyse the legal regimes of belligerent occupation and annexation in international law, with particular attention to their contemporary relevance and the challenges posed by long-term occupations. The first part lays the theoretical groundwork by exploring the sources, definitions, and essential characteristics of the law of occupation, as well as the development and legal contours of the prohibition of annexation. These chapters seek to clarify the conceptual distinctions between the two regimes and assess the normative frameworks that underpin them, both historically and in the post-1945 legal order. The second part of the thesis turns to case studies to assess how these frameworks operate in practice. It focuses primarily on the Occupied Palestinian Territory (OPT), with detailed analysis of the 2024 Advisory Opinion issued by the International Court of Justice. The situation of the OPT is examined in light of ongoing debates surrounding prolonged occupation, de facto annexation, and the legality of Israel’s presence under international law. Building on this, the thesis evaluates whether the legal framework developed for the OPT can be applied to other complex territorial situations, such as Western Sahara—where the obligation of non-recognition occupies a central role—and other relevant cases like the Chagos Archipelago. Through this comparative inquiry, the thesis aims to shed light on the consistency, limits, and normative power of the law on occupation and annexation in today’s international legal order.