This book presents the results of a study on the availability of law enforcement information in the EU, conducted for the European Commission. In order to strengthen the area of freedom, security and justice, the November 2004 Hague Programme called for an innovative approach towards cross-borderexchange of law enforcement relevant information. The principle introduced in this respect is that of availability of such information for law enforcement services throughout the EU, rendering the border-crossing of it largely irrelevant. The book contains two proposals. The first seeks to improve the cross-border exchange of law enforcement relevant information through the introduction of the principle of mutual recognition of 'pre-evidence warrants' as a primary way for implementing the availability concept. The second proposal offers a blueprint for a European Law Enforcement Services Index System (ELESIS), as an indispensable tool for supporting the availability of law enforcement relevant information throughout the EU. Both proposals take due account of extensive feedback received from experts involved in cross-border exchange of law enforcement information as well as from civil liberties organisations and data protection specialists. In addition, the responses of member states to relevant official questionnaires were collected and included. This book is essential reading for policy makers, judicial and law enforcement authorities throughout the European Union or from a broader international context. It will be appealing also to researchers and anyone involved or taking an interest in combating (cross-border) crime at a European or international level.