The Known Unknown: In Search For A Legal Structure Of The Significance Criterion Of The Siec Test

This article establishes the thesis that the notion of “significant” in the SIEC test of the European Merger Control Regulation lacks a clear legal concept in the current decisional practice. Antitrust economists and authorities have developed a set of theories of harm and have constantly refined them. Yet these theories often do not explain when certain price-effects or other implications of a merger have reached an intensity that is “significant” in the meaning of Article 2 EU Merger Regulation (EUMR).1 This renders the notion of significance a “known unknown” in legal terms. It is argued here that this legal uncertainty as to the relevant definition of “significant” has led to an increase in discretion in the handling of merger cases, a bias toward the detrimental effects of mergers, and a deflation of potential efficiency considerations. The article purports that, as a consequence, mergers are often treated similarly to cartels in concentrating on the elimination of competition and regarding efficiencies as a rare exemption for which the parties carry the burden of proof. Against this background, it shall be attempted to construe a unitary concept of significance that integrates efficiency analysis and includes a differentiated allocation of the burdens of proof for procompetitive and anticompetitive effects of mergers.