Examining Board: Professor Giorgio Monri, EUI (Supervisor)  Professor Giuliano Amato, former EUI  Professor Heike Schweitzer, University of Mannheim Germany  Professor Jerónimo Maillo, CEU San Pablo University Spain.Defence date: 19 November 2012This dissertation compares the approaches adopted in the EU competition law and the U.S.antitrust law towards joint ventures. The question is two-fold, including (i) the study of the specific problems raised by the strict conceptualisation of joint ventures under the EU policy, as compared to the U.S  and (ii) the possible insights the U.S. experience could offer in this area. This study demonstrates that the categorical approach in the EU has involved, over time, a number of specific issues that have been avoided in the U.S.. These relate, in particular, to the concepts employed to make the jurisdictional distinction between the mutually exclusive rules for mergers and horizontal agreements, which have caused a number of complications and led to unnecessary forum shopping. These differences are explained and their implications analysed in an attempt to help understand the approaches chosen and to explore how the EU policy could be further developed.  It emerges from this comparison that some of the highly technical issues concerning the legal characterization of joint ventures have, over time, reflected more fundamental differences in the enforcement attitude towards industrial cooperation between competitors as compared to mergers, including a different understanding of their effects on competition. This concerns, in particular, the controversial European  concentration privilege  favoring mergers and concentrative joint ventures over more limited cooperative alliances, whereas the U.S. enforcers have normally treated full integrations more suspect than partial ones.  Inspiring from the insights learned by studying the US approach, this dissertation concludes with a recommendation to revisit and clarify the EU approach to joint ventures in two specific areas. First, it calls for an explanation on how the substantive analysis of joint ventures under Article 101 TFEU compares with that of mergers, particularly in relation to the assessment of market power. Second, it suggests that the fate of Article 2(4) EUMR concerning the treatment of spill-over collusion be reconsidered in the current framework, including a clarification of its current function and purpose, if any