While the Eighteenth Amendment and the Volstead Act were in force there was much debate on the question as to whether international law required that foreign diplomats be exempt from their operation. Administrative regulations provided for such exemption, but an interesting article by Mr. Lawrence Preuss argued forcibly that no such exemption was required. The matter has become wholly academic now, although it might become practical again should Congress ever reenact a prohibition law for the District of Columbia. None the less, it may be instructive to call attention to what seems to be the only direct precedent in international practice, a precedent which has apparently remained buried until now.
In the case of the Mexican Union Railway, Ltd., decided in February, 1930, the British-Mexican Claims Commission, set up in accordance with the Convention of November 19,1926, added another stone to the somewhat unsteady structure of decisions on the Calvo Clause. The majority of the Commissioners enthusiastically adopted the considerationsof the United States-Mexican General Claims Commission in the North American Dredging Case, " not thinking it necessary to repeat them, or possible to express them better." Even the British Commissioner, Sir John Percival, who dissented, differed from the majority mainly in regard to the application of the opinion in the North American Dredging Case to the case at bar, and was not less cordial in his approval of that opinion.
The work of the recent claims commissions between Mexico and various other states constitutes an important body of material for the development of international adjudication. The revolutionary disturbances in Mexico between 1910 and 1920 resulted in considerable damage to aliens. On July 14, 1921, the Mexican Government by a circular letter announced its willingness to conclude claims conventions for the purpose of indemnifying such aliens. Six such claims conventions were concluded with the following governments: United States, France, Germany, Great Britain, Spain, and Italy.
The Statute and Rules of the Permanent Court of International Justice are only remotely analogous to the detailed codes of civil procedure with which lawyers practising before municipal courts are familiar. The instruments governing the procedure of the Permanent Court are sketch maps rather than meticulously detailed charts for the procedural voyage. Nor is the body of tradition of international arbitral procedure sufficiently developed to furnish reliable guides in all circumstances. Of necessity, the practice of the court must develop out of the cases which come before it. The method of growth of its procedural law finds typical illustration in the question of the treatment, and, in particular of the amendment, of the conclusions of the parties.
To the ever-increasing confusion of doctrine which makes up the law of sovereign immunity, the courts of the United States have added procedural complications which, though not as weighty, are nevertheless as puzzling as any of the substantive rules. Of recent years the United States Supreme Court and the lower Federal courts have often had occasion to consider the method whereby the question of immunity was raised. The result has been the evolution of a set of rules so vaguely defined in the decisions as to offer little guidance to the bench and bar, and withal of interest to the scholar who finds that these rules exist in no other judicial system.