The Introduction sketches the main technological and legal challenges LEAs face in criminal investigations when seeking to collect electronic evidence in the digital era. It gives an overview of the relevant legal framework at EU, Council of Europe and international level, including recent developments such as the e-Evidence Regulation and the Second Additional Protocol to the Cybercrime Convention, and identifies some missing pieces of the puzzle. Next, the chapter explains the main research objectives of this handbook, before presenting its overall structure and introducing the subsequent chapters.

Chapter 16 comparatively examines the national legislation in EU member states in order to reveal common patterns and differences in legal rules and their practical application with respect to gathering digital evidence for the purpose of criminal investigations. The study is essentially based on the information provided in the preceding book chapters, covering seven national legal systems selected for this research: Belgium, Estonia, Germany, Ireland, Luxembourg, Poland and Spain. The comparative analysis investigates not only the rules on access to digital evidence but also their broader legislative context. Indeed, before analysing how data can be obtained, it is important to understand the legal terminology and categorisations used in the different legal systems, as well as the national rules on data retention in light of the case law of the Court of Justice of the EU.

The Conclusion describes how, while the handbook started with the main technological and legal challenges regarding collection of digital evidence, the research shows that even though the challenges are shared by legal systems across the globe, the answers are not. Legal solutions to similar problems are fragmented, disparate and often unsatisfactory. Even if technology-neutral solutions are preferable to make sure hard-fought EU legislation and international agreements can stand the test of time, the legal reality appears to be quite different. Despite positive recent legal developments at EU and international levels, future approximation of national approaches seems highly desirable to enable LEAs to conduct effective criminal investigations to protect society and its citizens from new criminal phenomena. At the same time, protection of citizens’ fundamental rights should be reinforced, not just at the national level but in a cross-border context, considering that many criminal investigations now reach beyond national borders. Global initiatives are, however, hampered by tensions between democratic and non-democratic states, making a one-size-fits-all solution inadequate.

Chapter 21 provides an account of the governing legal framework with respect to the gathering of digital evidence by US law enforcement authorities (LEAs) and the rules that bind US service providers – an issue that, given the quantity of data of interest in the hands of US-based providers, increasingly matters to LEAs around the world. It describes the general statutory and constitutional scheme governing data collection in the United States, with a focus on the federal level. It then examines specific questions with respect to cross-border cooperation, particularly in light of the Clarifying Lawful Overseas Use of Data (CLOUD) Act, which seeks to better facilitate cross-border access to data, in specified circumstances, and in accordance with baseline procedural and substantive protections. The chapter’s concluding thoughts point to both the need for more attention to cross-border access to data and some of the lacunae in US law.