Arbitration — Ethiopia-Eritrea Boundary Commission — Mandate — Applicable law — Boundary dispute — Delimitation — Interpretation of the Commission’s mandate — Commission required to delimit and demarcate the boundary — Treaty interpretation — Evidence — Maps

Territory — Land boundaries — Delimitation — Boundary between Eritrea and Ethiopia — Delimitation by Boundary Commission — Prohibition from making decision ex aequo et bono — Rules of international law applicable to boundaries

Treaties — Interpretation of boundary treaty — Principles of interpretation — Good faith — Ordinary meaning — Object and purpose — Common will — Doctrine of “contemporaneity” — “Applicable international law” not limited to treaties but including rules applicable to boundaries — Subsequent conduct of the parties (effectivités) — Diplomatic and other similar exchanges and records — Acquiescence — Maps — Difference in legal consequences between maps annexed to treaty and those that are not — “Signature” of a map — Nature and effect of disclaimers

Rivers — River boundary — River boundaries follow the main channel of rivers — Main channel to be determined in dry season — Regard to the customary rights of the local people to have access to the river — Further determinations at the demarcation phase