Dictionary of National Biography, 1927 supplement/Oppenheim, Lassa Francis Lawrence
OPPENHEIM, LASSA FRANCIS LAWRENCE (1858–1919), jurist, was born near Frankfort-on-the-Main 30 March 1858, the third son of Aaron Oppenheim, by his wife, Adelheid Nossbaum, and was educated at the Frankfort gymnasium and at the universities of Göttingen, Berlin, Heidelberg, and Leipzig. From 1885 to 1891 he taught law in the university of Freiburg-im-Breisgau, and from 1891 to 1895 at Basle, being chiefly interested in criminal law; but in 1895 he settled in London, and henceforth devoted himself to the study of international law. He became naturalized in England in 1900. He lectured at the London School of Economics from 1898 to 1908, when he succeeded John Westlake [q.v.] in the Whewell chair of international law at Cambridge. He married in 1902 Elizabeth, daughter of Lieutenant-Colonel Phineas Cowan, and they had one daughter. He died at Cambridge 7 October 1919.
Oppenheim's chief work is International Law: A Treatise, of which the first volume, Peace, appeared in 1905, and the second, War and Neutrality, in 1906. It deservedly placed him among the foremost international jurists of his time, and was followed by his election to the Institut de Droit International, as associate in 1908, and as member in 1911. He belongs to the positive school of international jurists, who derive the rules of the science from custom and from the quasi-legislation of international conventions, and who regard it as the function of the jurist to ascertain and give precision to those rules, to criticize and suggest improvements, but not to create them, nor to select as valid only those of which he approves. Oppenheim protested against the tendency to deduce the law from phrases, too often uncritically accepted as self-evident truths; and he pleaded for the development among jurists of that wider sympathy with other nations which can only come from a study of their juristic systems and from the cultivation of an international outlook. He was joint author of the chapter on the laws of war on land in the official Manual of Military Law (sixth edition 1914) and was frequently consulted by the Foreign Office on points of international law.
The conduct of Germany in the European War horrified Oppenheim, and convinced him that the only hope of a better international order lay in the decisive victory of the Allies. He was not discouraged by the apparent overthrow of international law, pointing out that any case it affected only a relatively small part of the subject, the law of war, and revealed the paramount importance of a better organization of the peaceful relations of states. He strongly advocated a league of nations.
[The Times, 9 October 1919; British Year Book of International Law, 1920–1921; R. F. Roxburgh, Preface to Oppenheim's Treatise, containing a list of his writings on international law (third edition, 1920–1921); private information.]