This work explains and examines the important changes that have been made to the UK competition law regime in recent years, principally by the Enterprise and Regulatory Reform Act 2013 (ERRA) and the Consumer Rights Act 2015 (CRA). Put together by a team of experts from Eversheds LLP and Matrix Chambers, the work contains a thorough analysis of the problems of the status quo ante that acted as drivers for reform, an explanation and critique of the reforms to the regime, and commentary on their expected impact. Chapter 1 includes an important discussion of the question of independence of the newly created Competition and Markets Authority (CMA), as well as the interaction of the administrative, private enforcement, and criminal regimes. Chapter 2 considers the rationale for the merger of the Office of Fair Trading and the Competition Commission to create a single competition authority and comments on the CMA’s new institutional structure. Chapters 3–7 set out and analyse the changes to the regimes for administrative enforcement of the domestic and EU antitrust prohibitions, UK merger control, market investigations, antitrust enforcement by sectoral regulators, the criminal cartel offence, and private redress.