The proper definition of the relevant product market still is the lynchpin of competition law: defining the market too wide makes it impossible to capture the companies’ behavioural margins that are the result of market power and are not neutralized by competition; defining the market too narrow creates market power and forces undertakings under the application of Art. 82 EC, Art. 2 ECMR, § 19 German Competition Act. In European and German competition law the aspect of demand-side substitutability has been the most important criterion. The meaning of potential competition and especially of supply-side substitutability has not been systematically grasped. The book therefore re-thinks the relevant questions of proper market definition.

The Author: Franz Jürgen Säcker, Director of the Institute for German and European Economic, Competition and Regulation Law at the Freie Universität Berlin; Scholarship of the Studienstiftung des deutschen Volkes, 1966 Doctorate (Dr. iur.) in Law of the University of Cologne and 1971 Doctorate (Dr. rer. pol.) in Economic Sciences; offers of chairs at the Universities of Berlin, Augsburg, Bielefeld, Innsbruck, Tübingen, Hamburg, Kiel; 1971 Full Professor at the Freie Universität Berlin; 1973-1984 Judge of the Cartel Senate of the High Court Berlin (Kammergericht); since 1994 Director of the Institute for German and European Economic, Competition and Regulation Law at the Freie Universität Berlin and Executive Director of the Institute for Energy and Regulation Law Berlin e.V.; 1997 Doctorate honoris causa (h.c.) of the Russian Academy of Science, Institute for Law and State.