International Court of Justice — Merits — Boundary dispute — Dispute between Botswana and Namibia submitted to Court by Special Agreement for final and binding determination — Determination of boundary around Kasikili/Sedudu Island — Determination of legal status of Kasikili/Sedudu Island — Applicable law — Anglo-German Treaty, 1890 — Rules and principles of international law — United Nations Charter — Charter and resolution of Organization of African Unity — Principle of uti possidetis — Respect for frontiers existing upon national independence — Anglo-German Treaty, 1890, Article III — Delimitation of spheres of influence in south-west Africa — Boundary line following centre or thalweg of main channel of Chobe River — Whether northern and western channel constituting main channel as asserted by Botswana — Whether southern channel constituting main channel as asserted by Namibia — Boundary between Botswana and Namibia around Island — Whether Island part of territory of Botswana or Namibia — Whether Namibia having prescriptive title to Island

Rivers — Riverain boundary — Chobe River — Main channel of Chobe River — Boundary between Botswana and Namibia around Kasikili/Sedudu Island following main channel of Chobe River — Anglo-German Treaty, 1890, Article III — Location of main channel being main dispute between Parties — Whether northern and western channel constituting main channel as asserted by Botswana — Whether southern channel constituting main channel as asserted by Namibia — Boundary between Botswana and Namibia around Island

Rivers — Chobe River — Kasane communiqué — Undertaking between Parties — Nationals of and vessels flying flags of Botswana and Namibia to enjoy equal national treatment in two channels of Chobe River around Island — Navigation and environmental protection

Treaties — Interpretation — Application — Anglo-German Treaty, 1890 — Vienna Convention on the Law of Treaties, 1969, Article 31 — Article 31 reflecting customary international law — Anglo-German Treaty, 1890, Article III — Delimitation of spheres of influence in south-west Africa — Boundary line following centre or thalweg of main channel of Chobe River — Whether centre and thalweg synonyms — Determination of location of main channel — Real dispute between Parties — Whether northern and western channel constituting main channel as asserted by Botswana — Whether southern channel constituting main channel as asserted by Namibia — Ordinary meaning of words “main channel” — Criteria for determination — Relevance and applicability — Depth — Flow — Bed profile configuration — Navigability — Object and purpose of 1890 Treaty — Travaux préparatoires to 1890 Treaty — Subsequent practice of parties to 1890 Treaty — Map evidence

Territory — Sovereignty — Kasikili/Sedudu Island — Determination of legal status of Island — Whether Namibia and predecessors having prescriptive title to Island — Whether Special Agreement precluding examination of prescriptive claim — Whether acts of State authority by Namibia on Island

State succession — European colonial powers partitioning Africa — Great Britain and Germany signing treaty delimiting respective spheres of influence in south-west Africa — Botswana gaining independence in 1966 — Namibia gaining independence in 1990 — Delimitation of boundary between Namibia and Botswana around Kasikili/Sedudu Island — Determination of legal status of Island — Anglo-German Treaty, 1890 — Rules and principles of international law — United Nations Charter — Charter and resolution of Organization of African Unity — Principle of uti possidetis — Respect for frontiers existing upon national independence

197 International Court of Justice — Intervention — Procedure — Application by the Philippines for permission to intervene — Whether filed out of time — Whether containing formal defect — Whether absence of jurisdictional link barring intervention — Whether Philippines establishing interest of a legal nature — Whether limited to dispositif under Article 62 of Statute of Court — Nature of interest necessary — Whether needing to have same subject-matter as case — Whether claim of sovereignty in North Borneo could be affected by Court’s reasoning or interpretation of treaties in case concerning Pulau Ligitan and Pulau Sipadan — 1878 grant claimed as primary source of title — Other instruments — Whether Philippines discharging burden under Article 62 of Statute of Court — Whether object of intervention inappropriate — Article 81 of Rules of Court

Territory — Sovereignty — Pulau Ligitan and Pulau Sipadan — Whether islands belonging to Indonesia or Malaysia — Indonesia claiming title based on 1891 Convention — Interpretation of Article IV of 1891 Convention — Articles 31 and 32 of Vienna Convention on the Law of Treaties, 1969 — Whether supplementary means confirming interpretation of text — Cartographic evidence — Whether Indonesia or Malaysia obtaining title to Ligitan and Sipadan by succession — Whether Indonesia having title as successor to the Netherlands and Sultan of Bulungan — Whether Malaysia having title on basis of series of transfers of title from Sultan of Sulu — Whether Indonesia or Malaysia having title to Ligitan and Sipadan on basis of effectivités — Judgment on Merits

Treaties — Interpretation — 1891 Convention — Article IV of 1891 Convention — Applicable rules — Vienna Convention on the Law of Treaties, 1969 — Articles 31 and 32 of Vienna Convention — Customary international law — Context of 1891 Convention — Object and purpose of 1891 Convention — Whether supplementary means confirming interpretation of text of 1891 Convention — Travaux préparatoires — Circumstances of conclusion — Subsequent practice of parties — Cartographic evidence

State succession — Independence of colonial territories — Indonesia and Malaysia — Successor States of Netherlands and Great Britain — Whether obtaining title to Pulau Ligitan and Pulau Sipadan by succession — Contracts between the Netherlands and Sultanate of Bulungan — Whether Ligitan and Sipadan belonging to possessions of Sultan of Bulungan — Whether Malaysia having treaty-based title to Ligitan and Sipadan — Whether belonging to Sultan of Sulu — Whether uninterrupted series of transfers of title from Sultan of Sulu to Spain, United States, Great Britain on behalf of State of North Borneo, United Kingdom and Malaysia

Territory — Sovereignty — Pulau Ligitan and Pulau Sipadan — Effectivités — Whether Indonesia or Malaysia having title on basis of effectivités — Circumstances to be taken into account — Very small islands uninhabited or not permanently inhabited — Character of activities relied on by Indonesia — Whether constituting acts à titre de souverain — Character of activities relied on by Malaysia in own name and as successor State of Great Britain — Measures to regulate turtle egg collection and establish bird reserve — Legal relevance of lighthouse construction — Title on basis of effectivités

International Court of Justice — Chamber — Frontier dispute between Benin and Niger — Parties jointly submitting dispute to Chamber of Court by Special Agreement — Parties seeking definitive delimitation of whole boundary — Parties requesting Court to specify ownership of islands, in particular Lété Island — Boundary divided into two sectors — Determination of course of boundary in River Niger sector — Ownership of islands in River Niger, in particular Lété Island — Determination of course of boundary in River Mekrou sector — Article 2(a), (b) and (c) of Special Agreement — Applicable law — Rules and principles of international law — Article 38(1) of Statute of International Court of Justice — Principle of uti possidetis juris — Article 6 of Special Agreement

Territory — Sovereignty — Boundary between Benin and Niger — River Niger sector — Delimitation on basis of uti possidetis juris principle — Benin and Niger former colonies of French West Africa — Benin and Niger becoming independent on 1 and 3 August 1960 respectively — Determination of boundary inherited from French administration on 1 and 3 August 1960 — Critical date — French colonial law — Cartographic and other evidence — Relevance — Main navigable channel of River Niger at dates of independence — Colonial boundaries becoming international frontiers upon independence — Whether evidence of title on basis of colonial regulative or administrative acts — Legal relationship between effectivités and title — Effectivités — Determination of precise location of boundary line in main navigable channel of River Niger at dates of independence — Article 2(a) of Special Agreement

Territory — Sovereignty — Islands in River Niger sector — Island of Lété — Determination of boundary in River Niger — Consequent title to islands — Appearance or disappearance of islands — Whether determination of ownership of islands prejudicing private law rights — Article 2(b) of Special Agreement

Territory — Sovereignty — Boundary between Benin and Niger — Bridges — River Niger sector — Niger requesting determination of boundary on two bridges between Gaya and Malanville — Whether Chamber having jurisdiction to determine boundary on bridges — Whether any finding prejudicing joint ownership of bridges — Whether prejudicing arrangements regarding use and maintenance — Article 2(a) of Special Agreement

Territory — Sovereignty — Boundary between Benin and Niger — River Mekrou sector — Delimitation on basis of uti possidetis juris principle — Benin and Niger former colonies of French West Africa — Benin and Niger becoming independent on 1 and 3 August 1960 respectively — Critical date — Determination of boundary inherited from French administration on 1 and 3 August 1960 — Examination of legal titles — French colonial law — Cartographic and other evidence — Relevance — Interpretation and application of legal titles by colonial administrative authorities — Effectivités — Relevance — Exact location of boundary — Whether boundary following course of thalweg or median line of River Mekrou — Article 2(c) of Special Agreement

State succession — Colonies — States in western Africa — Benin and Niger formerly part of French West Africa — Benin formerly colony of Dahomey — Governor-General of French West Africa having power to determine boundaries of colonies — Benin becoming independent on 1 August 1960 — Niger becoming independent on 3 August 1960 — Critical date — States succeeding to frontiers inherited from colonialism — Intangibility of frontiers — Principle of uti possidetis juris — Boundary between Benin and Niger on dates of independence

Territory — Sovereignty — Original title — Prescription — Conduct — Acquiescence — Islands — Small island near the coasts of Malaysia, Singapore and Indonesia — Whether originally part of the territory of the Sultanate of Johor — Whether Johor losing title by virtue of prescription — Difference between prescription and estoppel — Construction by Singapore of lighthouse on island — Acts manifesting intention to act à titre de souverain — Correspondence between Johor and Singapore prior to independence — Whether involving recognition of Singapore’s title — Rocks located close to the island — Whether also acquired by Singapore — Low-tide elevation — Whether capable of separate acquisition — Whether sovereignty residing with State in whose territorial waters feature located

Sea — Maritime features — Low-tide elevation — Whether capable of separate acquisition — Whether appertaining to State on basis of location in territorial waters

States — Statehood in seventeenth century — Sultanate of Johor — Recognition as sovereign State — Title to islands — Relations with colonial powers during nineteenth and twentieth centuries

State succession — Independence of colonial territories — Singapore and Malaysia — Relations between colonial authorities in Singapore and Government of Johor during colonial period — Relations at time of independence — Secession of Singapore from Malaysia — Title to territory

Rivers — Boundary rivers — Navigation — San Juan River forming boundary between Costa Rica and Nicaragua — 1858 Treaty between Costa Rica and Nicaragua — International border fixed on the Costa Rican bank of the river — Entire territory of the river within the sovereignty of Nicaragua — Right of navigation “con objetos de comercio” granted to Costa Rican vessels — Interpretation of treaty — Whether extending to carriage of passengers, including tourists — Navigation by members of Costa Rican riparian communities for purpose of everyday needs — Use of river by Costa Rican official vessels — Regulatory powers of Nicaragua

Treaties — Interpretation — Principles of interpretation — Vienna Convention on the Law of Treaties, 1969 — Whether terms in treaty of long duration to be given an evolving meaning — Treaty imposing restriction on sovereignty of State within its own territory — Whether justifying restrictive interpretation — 1858 Treaty between Costa Rica and Nicaragua regarding sovereignty over, and navigation on, the San Juan River

Sources of international law — Customary international law — Customary practices by riparian communities along border river — Whether capable of giving rise to customary law rights regarding navigation and subsistence fishing

International Court of Justice — Remedies — Presumption that State will comply with judgment of the Court — Whether appropriate to order future compliance