This book highlights the criminal framework legislation developed by the UN Security Council and the EU in the aftermath of the terrorist attacks in the USA in 2001, and studies the implementation of these rules in six European legal orders. It contains a thorough analysis of the concept of terrorist offences, including complex issues such as actions by armed forces and resistance movements. It also explores the broad criminalisation of preparatory acts, including the participation in terrorist groups, and discusses the extended application of national law to offences committed abroad. More generally, the book sheds light on the interplay between global, regional and national regulation and contributes to a better understanding of national differences in the field of criminal law.