Applied to public enforcement, the concern for value for money in the public sector makes discretionary decision-making a target for reform. UK competition policy has already been reformed in favour of a more prohibitive legal regime. I isolate some discretionary features in the previous competition regime, and examine their consequences on decisions. Extant empirical competition studies rely on case-level analysis. To deepen the analysis, I disaggregate enforcement data at company level, on abuse of dominance cases published by the UK national competition authority, between 1970 and 2003. Econometric analysis confirms that decisions still depend on the economic facts of the case. Additionally, decisions are shown not to be neutral to the investigation process itself, but actually to depend on the specific assortments and hierarchy amongst investi- gators. Extensive experience of chairing investigations makes case chairmen tougher: the more experienced the case chairman, the more likely an adverse finding against a company. The strength of the discretionary power of the case chairman does not, how- ever, destroy all the potential benefits of the more onerous method of making decisions in a panel. Panel members unaccustomed to a given case chairman exert a calming effect on an experienced case chairman's tendency towards more adverse findings, which can be interpreted as a sign of effective information aggregation. The controversial use of profitability analysis in competition deci- sions affects only decisions where the abuses investigated directly involve excessive pricing. Furthermore, companies alleged to have engaged in infringements where economic theory recommends more active intervention, respond to de facto incentives to change their behaviour as the investigation starts: reported profitability levels exhibit a marked reduction in the financial years during the inves- tigation, compared to the pre-investigation years. Within-tenure experience, the use of profitability, and collegiality effectively in- jected more discretion into public enforcement decisions.

Competition between trade rivals in a marketplace operating within a common law-based legal system is regulated primarily by two fairly distinct branches of the law: the prohibitions against anti-competitive conduct imposed by the competition law framework, and the common law restraints against acts of “unfair competition” that attract liability under the economic torts. This dissertation aims to critically examine both these legal frameworks and provide an integrated account of how these branches of the law distinguish between lawful and unlawful modes of competitive conduct. By scrutinising the doctrinal and policy foundations that underlie each of these legal frameworks, common thematic strands that may not be immediately apparent to lawyers working exclusively in either field will be exposed, while fundamental differences between their respective inner workings will also be uncovered in the process. Engaging in such a comparative exercise will facilitate a deeper understanding of the contrasting objectives and jurisprudential approaches associated with each legal framework which, in turn, sheds some light on the nature of their relationship with each other and the extent to which legal developments in one field ought to influence, or be influenced by, the other. Besides evaluating how and why the common law economic torts operate differently from the competition law prohibitions in circumscribing the liberty of individual competitors to inflict economic harm upon their trade rivals, this dissertation will also analyse selected types of commercial conduct which are regarded as lawful under one framework but unlawful by the other, and contrast them with scenarios which could attract overlapping legal liability under both legal frameworks. In addition, this dissertation will explore a selection of legal issues arising from the doctrinal interaction between these areas of the law that may confront the courts as these two legal frameworks continue to develop in tandem with each other.