Benjamin Perrin, ed. Modern warfare: Armed groups, private militaries, humanitarian organizations, and the law Vancouver: UBC Press, 2012. 395 pp $99.00 (hardcover) ISBN 978-0774822329For over two decades now, academics and policy makers have been confronted with the challenges - such as security privatization, endemic urban violence, and lowlevel insurgencies - that come with the application of international humanitarian law in the post-Cold War environment. The contributions in Modem Warfare address the gap between the theory and the practice of international humanitarian law across contexts. Three central contributions set this book apart: first, it analyzes emerging issues by drawing from multidisciplinary perspectives; second, it assesses the impact of non-state actors on the prevailing humanitarian framework; and third, it tackles ongoing debates as they relate to humanitarian organizations, security privatization, humanitarian space, and urban violence.In the first section, the contributors explore the question of how to persuade nonstate armed groups to observe international humanitarian law in various contexts. Rene Provost concludes that what he refers to as asymmetrical non-reciprocity has proven inadequate in persuading non-state armed groups to obey international humanitarian law in armed conflicts. He argues instead for broadening the participation of non-state actors, which will not merely promote normative convergence but will also reach a more effective consensus than one that originates in a single category of participants (33). As Sophie Rondeau suggests, beyond the call for broader participation, it is necessary to include non-state armed groups in decisions about how the rules of international humanitarian law can be complied with. This solution, she argues, would be more constructive in fostering a culture of compliance.Some contributors express a different view. For example, Sandesh Sivakumaran argues that the involvement of non-state armed groups in the enforcement of international humanitarian law would cause unintended problems related to sovereignty and public international law. In Colombia and Myanmar, the challenges involved in negotiations with non-state armed groups, as discussed in the chapters by Elisabeth Decrey Warner, Jonathan Somer, and Pascal Bongard, illustrate this point.The volume also addresses the legitimacy of certain practices of modern warfare, such as humanitarian organizations hiring private security companies (PSCs). Benjamin Perrin analyzes the advantages and disadvantages of PSC involvement in humanitarian assistance and then advances two critical questions. First, if humanitarian organizations hire PSCs, would humanitarian personnel lose their protected status under international humanitarian law? Second, would PSC involvement affect humanitarian assistance? These questions will no doubt guide future scholarship that is at the intersection of international law and politics, addressing the security functions of non-state actors. …