Conflicts of jurisdiction arise when several states, in accordance with their respective national criminal laws, claim jurisdictional power for themselves to try a suspect for one and the same crime. The cumulation of national jurisdictional powers puts a suspect at the risk of prosecution by several states or even multiple penalisation for the same offense. Parallel prosecution in several states can lead to a conflict-ridden "race" for the first court decision (following the "first come first served" principle). Such uncoordinated rivalry between several national jurisdictional powers harbours the potential for inter-state conflict that should be avoided, not least in an "area of freedom, security and justice". The proposals presented in this volume for solving conflicts of jurisdiction were developed by the European Working Group, a group of international researchers over a period of two years.