Foreign States — Respect for interests of foreign States — Dispute between private litigants involving interests of foreign States — Dispute between private litigants involved with territorial dispute between States — Whether properly justiciable in municipal court of third State — International comity — Judicial restraint — Discovery of documents — Request for disclosure of documents handed in confidence to private litigant by foreign sovereign — Whether in public interest to refuse disclosure — Sovereign immunity — Act of State doctrine — Law of the sea — Territorial waters — Extent — The law of England