Presumptions and short-cut rules in abuse regulation: (where) do EU and U.S. antitrust approaches meet?

This chapter seeks to make sense of the existence of such rules and presumptions and their potential with a view to contributing to debates on a more coordinated or structured enforcement of abuse regulation provisions on a global scale. With that purpose, it compares the setup and role of legal presumptions of dominance/monopolisation and of abusive behaviour as benchmarks for antitrust enforcement in both EU and U.S. law. Section two of the paper identifies and distinguishes two different categories of legal techniques (short-cut rules and evidentiary presumptions) facilitating the enforcement of abuse regulation. General policy and case law evolutions allow to infer that both legal systems seemingly attest to a move away from short-cut rules in favour of evidentiary presumptions. In the U.S., the latter kind of presumptions are also even more limited in scope and scale. Section three will summarily address those evolutions in relation to both legal orders. Section four questions to what extent a reliance on different regulatory enforcement techniques in both legal orders could provide fertile ground for convergence amongst EU and U.S. abuse practices and whether the development of effectively converging legal presumptions actually offers a way forward for emerging and more established competition law jurisdictions across the globe. Focus will particularly be put on legal presumptions, as they have become seemingly more important in both legal orders over the past two decades.