Sovereign immunity — Foreign State — Restrictive theory — Acts iure imperii and iure gestionis — Charter of vessel by Government of Zambia — Liability for demurrage and damages — Action for attachment of cargo to found jurisdiction — Whether restrictive or absolute theory of sovereign immunity to be applied

International law in general — Nature and binding force — Changes in rules of international law — Duty of municipal courts to ascertain nature and extent of such change — Whether rule of stare decisis exists in international law — Duty of municipal courts to apply new rules of international law in appropriate circumstances — Whether rule of stare decisis in municipal law affected — Relationship of international law and municipal law — Whether international law part of the law of South Africa — Sovereign immunity — Restrictive and absolute doctrines — Conflict with South African legislation or common law — The law of South Africa