Prominent among the quests for post-9/11 security are developments in surveillance, especially at national borders. These developments are not new, but many of them have been extended and intensified. The result? More and more people and populations are counted as suspicious and, at the same time, surveillance techniques become increasingly opaque and secretive. Lyon argues that in the aftermath of 9/11 there have been qualitative changes in the security climate: diverse databases containing personal information are being integrated; biometric identifiers, such as iris scans, are becoming more popular; consumer data are merged with those obtained for policing and intelligence, both nationally and across borders. This all contributes to the creation of ever-widening webs of surveillance. But these systems also sort people into categories for differential treatment, the most obvious case being that of racial profiling. This book assesses the consequences of these trends. Lyon argues that while extraordinary legal measures and high-tech systems are being adopted, promises made on their behalf - that terrorism can be prevented - are hard to justify. Furthermore, intensifying surveillance will have social consequences whose effects could be far-reaching: the undermining of social trust and of democratic participation.