Fraenkel was born in a Jewish family in Cologne. He served during the First World War from 1916 to 1918 in the German Army. He wrote his dissertationin law about The void labour contract, under Hugo Sinzheimer. During the Weimar Republic he worked as a lawyer for labor law with Franz Leopold Neumann, published scientific publications and was engaged in socialist politics. Having been a soldier in World War I, he was still allowed to work to a limited extent even after the Nazis came to power in 1933. He was connected to several resistance groups such as the Internationaler Sozialistischer Kampfbund. In 1938 he finally immigrated to the United Kingdom, in 1939 to the United States. Shortly after arriving in New York Fraenkel moved to Chicago, where he studied American law at the University of Chicago Law School, graduating in 1941. During this period he revised and completed a manuscript that he had brought with him from Germany. In this work, published in 1941 as The Dual State, he analyses the political system of the Nazi state. For Fraenkel there coexisted in the Nazi government a "normative state", which secured the continuation of capitalist society for those Germans not threatened by Nazism, and a "prerogative state", which used legal sanctions as well as brutal violence against people considered to be enemies of Nazism and Nazi Germany. Fraenkel lectured at the New School for Social Research. From 1945 on Fraenkel was an adviser to the American government but was soon dissatisfied with their policy of occupation in Korea. For the United Nations he was supposed to be one of the people to prepare free elections in Korea, but the Korean War made the elections impossible and forced Fraenkel to leave the country. In 1951 Fraenkel returned to Germany. He became a lecturer at the Deutsche Hochschule für Politik in Berlin and later a professor at the Freie Universität Berlin, where he founded the John F. Kennedy-Institute for North American Studies. He considered his writings to be normative, his concept of pluralism was meant to criticize the existing political system. Those among his students who were active in the 1968 movement, however, saw his American-influenced theories as defending monopolistic capitalism. He died in Berlin.
