One European legal framework for surveillance: The ECtHR’s expanded legality testing copied by the CJEU

In this chapter, we focus on developments with regard to the legality principle in the context of surveillance in the realm of criminal law and intelligence work by secret services. A more rigorous interpretation of the legality principle in post-Klass surveillance case law certainly qualifies as one of the most remarkable developments in the European Courts’ case law on surveillance. In particular, we will show that the strict approach towards the legality requirement enshrined in Article 8 ECHR and adopted by the ECtHR in Huvig v France in the context of telephone surveillance has been reapplied in all of the following judgments of the Strasbourg Court and even adopted by the CJEU in the context of other surveillance practices.