Lassa Francis Lawrence Oppenheim (March 30, 1858 – October 7, 1919) was a renowned German jurist. He is regarded by many as the father of the modern discipline of international law, especially the hard legal positivist school of thought. He inspired Joseph Raz and Prosper Weil.
Born in Windecken near Frankfurt, Germany and educated at the Universities of Berlin, Göttingen, Heidelberg and Leipzig. In 1881 he obtained his PhD of Law at the University of Göttingen. Then he completed his Habilitation at Freiburg (Breisgau). He moved to the United Kingdom in 1895, acquiring citizenship in 1900 and lived there until his death.
He first lectured at the London School of Economics and in 1908 became the Whewell Professor of International Law in the University of Cambridge. He is the author of the internationally renowned International Law: A Treatise, the first edition of which was published in 1905-1906. The eighth edition of the part on peace was edited by Sir Hersch Lauterpacht; the ninth and most recent edition of the same part was co-edited by Sir Robert Jennings and Sir Arthur Watts. The work is still considered a standard text of International Law.
He published: