L. (Lassa) Oppenheim

Born in Windecken near Frankfurt am Main on March 30, 1858, Lassa Francis Lawrence Oppenheim studied law in Germany and later continued his career in Switzerland and Britain. He joined the London School of Economics in the 1890s and went on to become Whewell Professor of International Law at the University of Cambridge.

Oppenheim is often remembered as one of the founding figures of modern international law. He was especially associated with a positivist approach, emphasizing the rules and customs that states actually recognize and follow. His best-known work, International Law: A Treatise (1905–06), became a major reference for English-speaking students, scholars, and practitioners.

He died in Cambridge on October 7, 1919. More than a century later, his work still marks an important moment in the effort to present international law as a rigorous and coherent discipline.