Arbitration — International maritime boundary award — Dispute regarding boundary line dividing offshore areas of two Canadian Provinces — Oil, gas and mineral rights on continental shelf — Accord Acts — Dispute settlement provisions — Terms of Reference — Canadian Provinces to be treated as States for purposes of arbitration — Arbitration in two stages — Phase One to determine whether boundary line resolved by agreement — 1964 Joint Statement — 1972 Communiqué — Subsequent practice of Parties — Relevance — Phase Two to determine line in absence of agreement — Applicable law

Sea — Delimitation of maritime boundaries between Parties — Continental shelf — Delimitation of continental shelf beyond 200 nautical mile limit to outer edge of continental margin — Method of delimitation — Practical method — Equitable result — Geographical context — Governing law — Whether fourth Geneva Convention on the Continental Shelf, 1958 applicable — Article 6 of Geneva Convention — Provisional strict equidistance line — Whether requiring adjustment — Conduct of Parties — Relevant geographical circumstances — Whether proportionality test relevant

Treaties — Geneva Convention on the Continental Shelf, 1958, Article 6 — United Nations Convention on the Law of the Sea, 1982, Article 83(1) and (4) — Customary international law — Law governing maritime delimitation — Unity — Flexibility