L. (Lassa) Oppenheim

Born in 1858 in what is now Germany, Lassa Francis Lawrence Oppenheim studied law at several German universities and later taught before moving to Britain. He became a British subject and went on to build a major academic career in international law.

Oppenheim taught at the London School of Economics and later at the University of Cambridge. He is especially remembered for International Law: A Treatise (published in two volumes in 1905–06), a work that organized international law around the actual agreements and customs of states and had wide influence on later scholarship.

He died in 1919, but his writing remained important long after his lifetime. For readers interested in how modern international law was systematized in the early twentieth century, his work still marks an important starting point.