Abuse of dominance is arguably the most complex area in competition law. It presupposes distinctions between anticompetitive exclusionary conduct and competition on the merits, and between legitimate and ‘exploitative’ terms or prices. Such distinctions are rarely clear in practice. The task is more challenging still where antitrust authorities apply these principles to new markets, for example, in the digital sector, where prior case law and principles developed in traditional industries may be ill suited to capture rapid changes in competitive structures and consumer demand. Small wonder that there is often divergence in the enforcement priorities and practice of competition authorities around the world.