This book represents the fruits of 40 years of academic endeavour in the field of police and judicial cooperation in Europe. My interest in the subject was awakened in the mid-1970s in the course of my research into the political history of policing systems in Europe since the second half of the eighteenth century. That research – which culminated in my thesis in 1978 entitled Opdat de macht een toevlucht zij? Een historische studie van de politieapparaat als een politieke instelling (Seeking Refuge in Power? A Historical Study of the Police as a Political Institution) (Antwerp, Kluwer) – demonstrated that collaboration between police services had occurred in many forms and in a variety of combinations during that period, particularly with regard to suppressing extreme or radical political opposition and investigating serious forms of crime. In other words, cross-border cooperation was an intrinsic component of the work of the police.

Moreover, around that time – 1975-1976 to be more precise – the basis of the cooperation between the member states of the European (Economic) Community in combating groups engaged in terrorism and other politically motivated violence was changing. In the utmost secrecy, the member states had reached agreement in Rome to join forces in this domain and form a network for intergovernmental cooperation in the field of law and order named after the city's famous fountain, the TREVI Group.

My fascination with police and judicial cooperation in Europe has only grown since that time, not least because in the last few decades this form of cooperation has really taken off in various guises in the European Union, for example by virtue of agreements like the Schengen Implementation Agreement of 1990 and the Convention on Mutual Assistance in Criminal Matters between the Member States of the European Union in 2000, but also the establishment of Europol and Eurojust to support the police and judicial cooperation between the member states.

This growing interest has led to a great many publications on the subject of this form of interstate cooperation, some of which arose from research projects in this field. Several of the projects concerned the collaboration between police services, local authorities and public prosecution services in the border region of the Netherlands, Germany and Belgium, in particular the Meuse-Rhine Euroregion.