By utilizing the professional career of one individual, Jean de Lanessan, this paper discusses some aspects of positivism and criminal legislation in France between 1880 and World War I. Lanessan was a biologist by training who possessed a long-standing interest in social issues that led to a second career as a politician. Lanessan, the biologist, influenced the practice of French criminology, whereas Lanessan, the politician, was instrumental in shaping legislation on crime.




















