Duff Development Co. v Goverment of Kelantan [1924] AC 797

1912 the Governement of Kelatan granted the appellant company a certain mining rights to be exercised in that state. There was an arbitration clause a dispute was referred to arbitration who made an award in favour of the company. In 1921 Kelantan applied to the Chancery division to set aside the award on the ground that Kelatan was a sovereign state. Before setting aside, the court asked the government the status of Kelantan and the British minister answered that Kelantan was an independent state and that GB did not exercise any sovereignty over Kelantan, notwithstanding that Kelantan had not political relations with other states but just through the King of England

Arguments to take the certificate as conclusive evidence cited by Lord Sumner: (Best evidence) the court has to inform itself from the best material available (One voice doctrine) courts and executive should follow the same approach in matters of foreign affairs. [Other argument suggested (not cited by the court) is when an element of recognition by the UK government is necessary] The government of Kelantan had not submitted to the jurisdiction of the court for the purpose of the proceedings to enforce the award, either by assenting to the arbitration clause or by applying to the court to set aside the award. Oppenheim ‘it is the practice of English courts to accept as conclusive statements by Secretary of Foreign affairs and Commonwealth Affairs relating to certain categories of questions of fact in the field or international affairs. In such cases the statement is conclusive, even in face of contrary evidence’ The ‘practice’ has been incorporated in statutes; State immunity act 1978, 21