The primary aim of this study as a whole is to examine how useful a safeguard the Convention is, and can be, in the sensitive area of national security law and practice. The first part of the book consists of an examination of the national security concept generally in the Convention and the context of national security concerns in European states. The second part of the book is devoted to detailed studies of secret surveillance and security data registers, both of the court and commission's case law and of national laws in the field. The third part of the book consists of an article-by-article analysis of the case law of the commission and the court dealing with national security. The book is of interest to academics, practising lawyers and legislators interested in human rights and national security issues.