Pre-print. Published in Jannemieke Ouwerkerk, Judit Altena, Jacob Őberg and Samuli Miettinen (2019) the Future of EU Criminal Justice Policy and Practice. Legal and criminological Perspectives. Leiden/ Boston: Brill Nijhoff. Page VII-XII Foreword. Towards evidence-informed law and policy making in the EU, some introductory notes from a criminologist. 1. Crime and criminal justice policies in motion We live on a daily diet of criminal justice narratives and images in which criminalisation and penalisation are mostly depicted as tied to the nation state. In reality, crimes cross borders easily and increasingly take place at least partially in cyber space. In a ‘world in motion’ in which products, services and people cross borders all the time, crime is all but an exception. 1 For the EU and its Member States, these developments pose major challenges. In reaction, collaborations in the Area of Freedom, Security and Justice have rapidly increased, which has also had serious implications for the policies within Member States. Not only do criminal justice actors work together more intensively and have more opportunities to do so, the Member States’ previously unquestioned competence to define criminal offences and the applicable criminal sanctions is also no longer a question outside the influence of EU law. We only have to think of the broad competences for the EU to enact legislation in several areas of crime, such as human trafficking, sexual exploitations and organised crime. These are deemed necessary when dealing with present realities of crime. The conference THE FUTURE OF EU CRIMINAL JUSTICE POLICY AND PRACTICE held at Leiden Law School, on which the present volume is based, touched upon several crucial issues regarding criminal justice policy, among them the relation between policy and practice and the role evidence can and should play therein. As Jannemieke Ouwerkerk 2 notes in her chapter, the EU aims to adopt legislation only when it has added value and does not go further than required. Social scientific evidence, including findings based on criminological research, is increasingly cited as an important aspect to take into account when designing laws and policies. This holds at the national level, but for reasons of legitimacy even more so at the EU level. As a result, the search for empirical evidence has moved up the agenda of EU crime policy and criminal law, but Christopher Harding and Joanna Beata Banach-Gutierrez note in their chapter 3 that finding evidence that something might work is: ‘a research activity beset with challenges and difficulty’. My introductory remarks to this innovative volume tie in with these observations and critically reflect on this ideal based on my own experiences as a criminologist and propose more modest and potentially more fruitful expectations from my own discipline of criminology. 2. The complexities of evidence The ideal of evidence-based laws and criminal justice policies is rooted in the medical metaphor. As Thibodeau, McClelland and Boroditsky observe: ‘Our language for discussing 1 KF Aas, ‘Analyzing a World in Motion’ (2007) 11 Theoretical Criminology 283. 2 Present volume, chapter 3. 3 Present volume, chapter 4.