This book deals with the gathering of evidence in cross-border investigations in Europe. The issue of obtaining evidence in and from European countries has been among the most debated issues of EU cross-border cooperation in criminal matters over the last two decades, going through periods of intensive discussions and showing an extraordinary adaptability to the evolution of EU legislation for criminal matters. On the other hand, the prosecution and investigations of cross-border cases pose unprecedented challenges in the European scenario, characterized by the increasing flow and activity of citizens over the territory of more than one country and therefore by the need to lay the foundations of a transcultural criminal justice system. The book analyses this complex topic starting with the current perspectives of EU legislation, thus providing a critical analysis of the legislative initiative aimed at introducing a new tool for gathering almost any type of evidence in other Member States, i.e., the European Investigation Order. On a second level, this study deals with the solution models and human rights challenges posed by the increasingly intensive dialogues between domestic and supranational case laws, and formulates essential guidelines for setting up a fair transnational enquiry system in Europe.