This study examines a key aspect of regulatory policy in the field of data protection, namely the frameworks governing the sharing of data for law enforcement purposes, both within the EU and between the EU and the US and other third party countries. The work features a thorough analysis of the main data-sharing instruments that have been used by law enforcement agencies and the intelligence services in the EU and in the US between 2001 to 2015. The study also explores the challenges to data protection which the current frameworks create, and explores the possible responses to those challenges at both EU and global levels. In offering a full overview of the current EU data-sharing instruments and their data protection rules, this book will be of significant benefit to scholars and policymakers working in areas related to privacy, data protection, national security and EU external relations.