The present Handbook aims to provide law enforcement and criminal justice officials with an accessible guide to assist them in dealing with some of the key issues that they face in their efforts to respond to terrorist and related crimes. It reviews the many challenges encountered by the various components of the criminal justice system in the prevention, investigation, prose cution and detention of alleged or convicted perpetrators of terrorist crimes. It offers guidance based on international standards and generally accepted good practices. Reference is made to the Basic Principles on the Role of Lawyers throughout the Handbook.