Digital Market Definition in the European Union, United States, and Brazil: Past, Present, and Future

Market definition is a core concept of competition law around the globe, including in the European Union, the United States, and Brazil. In all three jurisdictions, antitrust authorities are grappling with the challenges of digital markets, often dealing with the very same digital players. The provision of zero-price services, the multisided nature of many digital platforms, and the implementation of entire digital ecosystems all challenge traditional approaches to market definition. But where there are common problems, there is a potential for common solutions. Through a comparative analysis of decisional practice relating to these past, present, and future challenges of digital market definition, this contribution maps the common ground already achieved while highlighting remaining gaps and possible solutions: for zero-price services—the past—it shows how a consensus has emerged on the theory and possible tools to define markets for ‘free’ services. On multisided platforms—the present—it finds that no such consensus has been reached yet, but strides are currently being made in developing an overall framework. And on digital ecosystems, it analyses how this challenge of the future requires the development of a coherent approach that can be based on cross-jurisdictional insights from the past and present.