The twelve refereed publications (drawn from over eighty-five journal articles and a number of books and books chapters) which form the basis of this PhD each deal with an environmental and social problem that poses some regulatory or competition issues. They may be contended to have arisen due to a range of market failures that can warrant intervention. In some cases they are argued to challenge market conduct and/or regulatory practice. The selection of papers is in my judgement broadly reflective of the range of topics investigated throughout my research career and also chosen to include early work as well as some of my most recent and ongoing work. A wide range of research methods are used and all of the publications are to varying degrees considered to be policy relevant. The submitted work includes primarily theoretical or conceptual studies, critical policy assessments, as well as studies reporting empirical work drawing either on quantitative or qualitative modes of analysis, or some combination of the two. Most of the research has been undertaken in a UK setting though some took place in a South African setting and all are explored within the framework of the available international literature. The first part of the thesis commentary provides an introduction with personal background, an explanation of the thesis structure and a review of the relevant literature, highlighting the key work informing the selected articles and explaining the research context in which they evolved and developed. Then the commentary presents a reflective critical analysis of the selected articles. Finally the commentary unfolds a critical appraisal of the contribution of the published works to the field of study (including citation analysis) and in relation to some of the articles a more qualitative discussion is presented.