During the Taisho and Showa eras, Japanese universities taught a subject called "German Law". In 1913, Theodor Sternberg (1878-1950) was appointed as lecturer in this subject at Todai University. He lived in Japan from this time until his death in 1950, without ever going back to Germany. Although, as a Jew and a liberal-socialist, he experienced a difficult life, his teaching influenced a number of im-portant Japanese jurists and politicians: Kawashima Takeyoshi (1909-1992), Ma-kino Eiichi (1878-1970), Suehiro Izutaro (1888-1951), Tanaka Kotaro (1890-1974), Wagatsuma Sakae (1897-1973) and others. Since the Meiji era, Japanese legal teaching had drawn its inspiration from the classical German "systematic" doctrine, based on the abstract analysis of ancient Roman Law. Sternberg introduced the teaching of a legal science closer to every-day life: the so-called "Freirecht", or "free law", involved the revaluation of legal rules originating from the courts and not only from the Parliament (judge-made law, jiyûhôron). This "free law" teaching opened the doors to legal sociology, which found its way to Japan from the United States after World War II. The arti-cle describes Sternberg's life, his works and their dissemination during his early years in Switzerland and Germany, as well as the 37 uninterrupted years he spent in Japan.