Evan - Sociology of law "Structuralism - Pacifism - Legal system. This short note honours the memory of William M. Evan, who passed away on December 25, 2009. A student of organisation theory who adopted a structuralist stance and, with his writings, a tireless campaigner for world peace, Evan played a role of paramount importance in the development of post-WW2 sociology of law. A co-founder of the ISA Research Committee on Sociology of Law, he edited important collective books and was himself the author of numerous studies and reflections in which he built up a consistent vision of the legal system and of its "open" relationships with other social systems.