This book examines how legal, political, and rights discourses, security policies and practices migrate and translate across the North Atlantic. The complex relationship between liberty and security has been fundamentally recast and contested in liberal democracies since the start of the 'global war on terror'. In addition to recognizing new agencies, political pressures, and new sensitivities to difference, it is important that not to over-state the novelty of the post-9/11 era: the war on terror simply made possible the intensification, expansion, or strengthening of policies already in existence, or simply enabled the shutting down of debate. Working from a common theoretical frame, if different disciplines, these chapters present policy-oriented analyses of the actual practices of security, policing, and law in the European Union and Canada. They focus on questions of risk and exception, state sovereignty and governance, liberty and rights, law and transparency, policing and security. In particular, the essays are concerned with charting how policies, practices, and ideas migrate between Canada, the EU and its member states. By taking ‘field’ approach to the study of security practices, the volume is not constrained by national case study or the solipsistic debates within subfields and bridges legal, political, and sociological analysis. It will be of much interest to students of critical security studies, sociology, law, global governance and IR in general. Mark B. Salter is Associate Professor at the School of Political Studies, University of Ottawa.