State immunity — Attachment and execution — Foreign central bank funds — Whether immune from attachment — Whether funds held for non-commercial purpose — Requirement to establish specific allocation of funds for sovereign purposes — European Convention on State Immunity, 1972, Article 23 — Divergence from existing rules of customary international law — Whether Convention rules applicable to non-parties

State immunity — Jurisdictional immunity — Commercial activity — Agreement for construction of milk pasteurization plant — Whether State party entitled to immunity in action for breach of contract — Whether nature or purpose of act decisive — Requirement of close connection between dispute and forum State

Sources of international law — Treaties — European Convention on State Immunity, 1972 — Whether declaratory of existing rules of customary international law — Whether applicable to States not party to Convention — The law of Switzerland