Interest among academics in private military companies (PMCs) that offer military and security services remains considerable, especially after the events that occurred in Baghdad's Nisour Square last September, when a Blackwater personal security detail killed 17 Iraqi civilians after it believed the convoy it was protecting was coming under attack. Since then there have been increasing calls for regulation of the industry, and for PMCs to be held to account for their actions. This book could not be better timed, given the subject, regulation of PMCs, and it makes a significant contribution to the academic literature on PMCs. At the same time, the editors have taken a comprehensive approach to the subject. The book is organised around four sets of questions. First, what is the basis and nature of the concerns raised by the PMC phenomenon? Second, how have problems leading to a call for the regulation been manifested in different regions and contexts? Third, what regulatory norms and institutions currently exist and how effective are they? And fourth, what role does the nascent market for military/security services play in regulation and where is it going? The problem, however, for those interested in the subject is that much of the book covers familiar ground. Moreover, it takes a decisively US slant, while those chapters that try to avoid a US-centric approach still frequently rely on the experiences of the US government with PMCs.

The book focuses on the nature of the acts carried out by PMC personnel that according to the authors require better regulation and accountability, especially as they take on more and more responsibility in war zones. The book is quick to identify that most of the existing regulation to control the use of lethal force in wars is directed at states and standing armies. Thus the question arises as to whether the present normative framework and accountability structures can adequately address this new environment, and much of the book is directed at answering this question.

The 13 chapters cover many of the key issues surrounding PMCs that are of concern to academics and policymakers alike. The first three chapters raise initial concerns about using private violence in place of state militaries. Percy is particularly effective here, laying out the moral objections to the use of private force. The chapter sets up the book well for what follows in later chapters. O'Brien's chapter, on the other hand, is a little disappointing. Much of what is covered in the chapter is already well documented, while his understanding of the industry's history is problematic. British PSCs trace their origins back to Watchguard International, which was set up by David Stirling, the founder of the Special Air Service (SAS), in 1967, after he helped to organise British and French mercenaries to fight in the civil war in Yemen during the early 1960s. In contrast, Leander's chapter gives a fresh perspective on the subject. Her discussion of how PMCs are able to influence policy because they can be seen as ‘security professionals’ is particularly interesting. While she is right to warn of the dangers this poses for governments, her evidence suggests this may be a problem for the US in particular.

McIntyre and Weiss's chapter is the only one that focuses exclusively on the role of PMCs in Africa. What is impressive about the chapter is the level of detail they manage to incorporate in such a short space. It is well researched. That said, there is a lot of academic literature on PMCs and weak governments. Isenberg has also produced a solid piece of research, this time on the role of PMCs in Iraq. Unfortunately, the chapter goes over well-trodden ground. Again as with McIntyre and Weiss the level of detail is impressive. Krahmann's chapter on PMCs and security sector reform (SSR) offers a different perspective on the role of PMCs. It is also very relevant, considering that many PMCs see SSR as the next market. This area is of growing interest to academics, and Krahmann has done a good job of warning us of the potential pitfalls of relying on the market to deliver SSR.

While the chapter on international law is well articulated, it offers nothing new to the debate on PMCs. The same is true of the chapters on state responsibility and domestic regulation. I also felt that the discussion on state responsibility lacked focus and in places was much more a general discussion about the subject. A better understanding of the industry's history might also have produced a more in-depth analysis. For example, it would have been interesting to note the author's opinions on the fact that Sandline personnel in Papua New Guinea were made special constables, thus (in theory) making them answerable to national law. Caparina's chapter offers nothing new, but is probably the best-articulated account of International Traffic in Arms Regulation (ITAR) and South Africa's Foreign Military Assistance Act that I have read.

The final section explores the role of the market in regulating the activities of PMCs. Avant examines the emergence of this market, drawing our attention to the lack of competition and transparency that exists at present. Avant is also concerned with the ease with which individuals can move between companies to avoid being disciplined for inappropriate behaviour. While the lack of other regulatory tools means that more emphasis has been placed on the market to bring about normative behaviour, in the end the market itself is too weak to guarantee specific standards. Indeed, the failings of the market are shown up in Cockayne's chapter that draws on principal-agent theory to examine the relationship between PMCs and their clients. While the chapter offers an interesting insight into this relationship, I felt the facts were being made to fit the theory instead of the theory explaining the facts about the industry. Dickinson's chapter was probably the most interesting in my opinion. She has certainly highlighted an underdeveloped area of research regarding PMCs. Most of the legal studies on the subject focus on international law, when in fact the best chance of controlling PMC behaviour at present is through contract law. Finally, Bearpark and Schulz consider the role of self-regulation in the absence of government regulation. They argue that this is a realistic approach, and will give a competitive advantage to those companies that sign up to self-regulation.

I have three concerns after reading the book. First, it tends to take a US angle. Even though some of the chapters try to extend their work beyond the US market, virtually all of the chapters rely on US examples to support their argument. Second, no attempt is made to explain the different histories between the UK and US companies, that may go some way to explaining why they behave differently. Third, some of the footnotes in the early chapters are doubtful. This aside, the empirical work is solid, lucid and thorough. As a piece of academic work the book achieves its task very well.