Arbitration — Compromis — Interpretation — Parties concluding two consecutive agreements — Agreement on Principles and Arbitration Agreement — Latter agreement taking priority — Parties unable to agree on definition of scope of dispute — Scope of dispute left to Tribunal to decide on the basis of the respective positions of the Parties — Critical date — Whether dispute confined to issues raised by Parties by a particular date — Compromis providing for arbitration proceedings in two stages — Effect on first stage of proceedings

Arbitration — Compromis — Territorial dispute — Tribunal required to decide on territorial sovereignty — Whether required to do more than determine relative merits of competing claims

Arbitration — Evidence — Admissibility — Territorial dispute — Whether evidence of acts occurring after a particular date inadmissible — Maps — Historical evidence — Evidence submitted in response to question from Tribunal member

Arbitration — Procedure — Ad hoc tribunal created by agreement between two States — Tribunal using services of Permanent Court of Arbitration — Submissions by Parties

Territory — Sovereignty — Historic claims — Whether international law contains doctrine of reversion of ancient title — Territory under sovereignty of Ottoman Empire — Whether title capable of reverting to State which existed prior to Ottoman period — Yemen — Evidence of prior sovereignty over Red Sea islands

Territory — Sovereignty — Historical consolidation — Prescription — Effectivités — Nature and effect — Requirements of international law — Display of authority — Exercise of State functions — Peaceful possession — Petroleum agreements — Construction and maintenance of lighthouses — Acts of possession performed by military forces during civil war — Evidence of acts of third States

Territory — Sovereignty — Islands — Contiguity — Principle that islands within territorial sea of State presumed to be part of that State — Circumstances in which presumption rebutted — Portico doctrine

Territory — Sovereignty — Treaties — Treaty creating objective legal status for territory — Treaty of Lausanne, 1923 — Peace Treaty with Italy, 1947 — Red Sea islands

Treaties — Effect — Doctrine of res inter alios acta — Interpretation — Treaties creating objective legal status for territory — Treaty of Lausanne, 1923 — Peace Treaty with Italy, 1947

War and armed conflict — Peace Treaties — Treaty of Lausanne, 1923 — Peace Treaty with Italy, 1947 — Eritrea-Yemen hostilities 1995 — Agreements ending conflict