Intelligence services perform a valuable service to democratic societies in protecting national security, including safeguarding the fundamental freedoms and human rights of their members. The secret nature of intelligence work can, however, put the services at odds with the principles of an open society. This applies in particular to international cooperation, where intelligence services try to keep secret why, how, with whom and when they cooperate with other states. Until relatively recently, international intelligence cooperation was a black box, impenetrable to public scrutiny, about which states gave very little or no information. The secrecy surrounding international cooperation was so high that it was thought to be impossible to address issues of accountability.

Against this backdrop, the aim of the guide is to provide practical and specific guidance on how accountability and oversight of international intelligence cooperation can be strengthened on the basis of practical examples. It is based on international comparative research of legal and institutional frameworks of intelligence oversight, combined with in-depth interviews with former intelligence officials and intelligence overseers. It covers recent developments in intelligence cooperation, domestic and international standards, as well as internal and external oversight of international cooperation. The guide is an invaluable and practical tool for everyone concerned about accountability in this important but challenging field.