Abgrenzung des relevanten Marktes: notwendig, nützlich, überflüssig?

In several contexts the competition law classifies the behaviour of an undertaking as permissible or impermissible depending on whether the firm has market power and in particular whether it has a dominant position. Usually the assessment of dominance starts with market definition, followed by calculation of market shares which are considered as a key criterion for the assessment of dominance.
This interdisciplinary work analyses this key cornerstone of the current analysis and especially the assumption that the market definition is necessary for the assessment of dominance which in turn depends on the size of market shares. The work shows that that there are so far no sufficient economic evidences for the use of market shares as a criterion for the analysis of market power. It develops a concept for the market definition as a first step for the assessment of market power. Furthermore, the work develops a new approach to conceive the legal concept of dominant position and to assess the dominant position in practice.