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"Market Definition as an Instrument in Competition Law. Study in the light of European and Vietnamese Law" thesis defended by Thi Thu Ha DAO under the supervision of Sylvaine PERUZZETTO, IRDEIC
on the December 4, 2019
13h30 Maurice Hauriou 

Market Definition as an Instrument in Competition Law. Study in the light of European and Vietnamese Law" thesis defended byThi Thu Ha DAO under the supervision of Sylvaine PERUZZETTO, IRDEIC

Abstract :

Market definition is one of the most important analytical tools used by the competition authorities to examine and evaluate competition problems. But it is also the most difficult subject of competition law and has been the subject of heated debate between lawyers and economists for decades. The issue has never been resolved once and for all. Indeed, since the beginning of this decade, Professor Louis Kaplow, the most recent “hostile proponent” to market definition, has questioned this procedure while arguing that it should be abandoned. At the same time, the American economists Carl Shapiro and Joseph Farrell propose an economic method named Upward Pricing Pressure as an alternative to market definition in analysing the competitive effects of mergers in markets with differentiated products. Several derived tests following the same principle were developed. The current debate seems to have taken on a more fundamental dimension, in particular since 2010 when the US competition authorities revised the Horizontal Merger Guidelines which state that market definition is not necessarily the first step in a merger analysis.


These important developments raise the question how European competition law should react. Should market definition remain a prerequisite for any competition analysis or should it be replaced by other quantitative methods? While the relevant market plays a role as an instrument of analysis in all areas of European competition law (cartel, abuse of dominant position and merger control), what would be the legal consequences of abandoning it altogether? From another perspective, could the exclusion of new economic methods have any repercussions in cases, such as in certain specific markets, where the definition of the relevant market using the hypothetical monopolist test (TMH) would not be the best way to assess anticompetitive effects? Is market definition based only on demand-side substitutability, in the current practice of the European Commission, an appropriate approach? In the context where the concept of relevant market is now commonly used in almost all countries where competition law exists, the impact that the evolution of European law, being one of the most advanced in the world, can have on others should not be underestimated. Vietnamese competition law would certainly be impacted as it is based on the principles of European law and its administrative model.


The issues raised will be addressed during the thesis by an in-depth interdisciplinary study that confronts legal and economic arguments with respect to the market definition.

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Additional information

Jury :

Mme Sylvaine POILLOT-PERUZZETTO  Toulouse 1 Capitole University  PHD Supervisor
Mme Monique LUBY-GAUCHER University  of Pau and  pays de l'Adour Reporter
M. Ngoc Dien NGUYEN National University of Viet Nam Reporter
Mme Laurence IDOT Paris II-Panthéon Assas University Examiner
Mme Catherine GRYNFOGEL oulouse 1 Capitole University Examiner
M. Pierre ZELENKO Linklaters LLP Examiner

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