This text provides an accessible and up-to-date introduction to criminal justice for all those undertaking degrees and foundation degrees in policing in the UK. It will also be relevant to UK degree courses in criminology and criminal justice. The book provides a holistic overview of the criminal justice system, an exploration of the roles of key players within the system, and how the police interact with these organizations. It examines some of the principles that underpin the 'modernization' of the police, in particular how the police collaborates with partner agencies and the rationale associated with the change agenda.