Sir Otto Kahn-Freund (1900–1979), jurist, was born in Frankfurt am Main on 17 November 1900, the only child of Richard Kahn-Freund, a merchant, and his wife, Carrie Freund. He grew up in a cultured Jewish household and though in religious matters he was agnostic, he himself said that the most important fact in his life had been the awareness of being a Jew. To this he attributed the passion for justice and the concern for the disadvantaged which lay at the root both of his interest in labour law and of his socialist convictions.
Kahn-Freund studied principally at the University of Frankfurt, where he was powerfully influenced by Hugo Sinzheimer, who first interested him in labour law. In 1929 he entered the judiciary as a judge of the Berlin labour court. He married in 1931 Elisabeth, daughter of Friedrich Klaiss, mechanic. She shared his political convictions and his interests. They had an adopted daughter.
When the Nazis came to power Kahn-Freund was already known for a small book criticizing the ideology behind the decisions of the supreme labour court, and he was soon in collision with the party. He refused to uphold the dismissal of employees of the radio service who were alleged to be communists and to have tried to sabotage Hitler's first broadcast. The result was his own dismissal and departure to England. There he became a student at the London School of Economics, which for the next thirty years was the focus of his life and which was ideally suited to one of his temperament and views. Appointed an assistant lecturer in 1936, he became a professor in 1951. He was also called to the bar by the Middle Temple in 1936 and was for a time in chambers with Patrick (later Lord) Devlin. He was naturalized in 1940.
Kahn-Freund was an outstandingly exciting lecturer, with a command of English which any native speaker might envy. The lecture was indeed his favourite medium and his most brilliant work originated in that form. He played an important part in the establishment of labour law as an independent area of legal study in England, and in his later years he was unquestionably its leading authority. He also enjoyed a great reputation on the continent and in the United States (he was for many years a visiting lecturer at the Yale law school). While he was later unhappy with some aspects of Labour's attitude in the 1970s to the position of trade unions, he would certainly have found much to regret in the statutory controls of union power introduced by Margaret Thatcher's administrations. In 1965 he was appointed to the royal commission on the reform of the trade unions and employers' associations. His hand can be seen in the legal sections of its report which reflected his view that Britain possessed a reasonably well functioning system of labour relations.
Though labour law was his dominant concern, Kahn-Freund was remarkable for the range of his interests. He was a respected authority on the conflict of laws, being one of the editors of the sixth to ninth editions of Dicey. He was also an enthusiastic promoter of the study of family law; there, as in labour law, he constantly emphasized the need to see legal rules in terms of their social and human consequences. He was also a passionate advocate of the European ideal and vigorously advanced the study of European law.
In 1964 Kahn-Freund was persuaded to move to the chair of comparative law at Oxford and a fellowship at Brasenose College. The comparative approach was a natural concomitant of his broad interests, but he brought to the subject also a capacity for striking generalization. For anyone less youthful in spirit and less appreciative of new experiences the transition from the London School of Economics to Oxford at the age of sixty-three might have been difficult, and indeed he was genially impatient of the constraints on rapid change imposed by the collegiate and tutorial systems, but he quickly became at home and during his seven years (his tenure of the chair was, exceptionally, extended) he was influential in the establishment in the syllabus not only of comparative law, but also family law, labour law, and European law. A naturally sociable man, he also enjoyed the friendly diversity of senior common room life.
After his retirement Kahn-Freund continued to lecture and to write and held visiting professorships at Paris and Cambridge. He became FBA in 1965 and an honorary bencher of the Middle Temple in 1969; he was given silk in 1972 and was knighted for his services to labour law in 1976. He held many honorary doctorates. He died at Haslemere, Surrey, on 16 August 1979. He was survived by his wife.