David Emmett, PhD retired from a 30-year career as a police officer in 1996, and has over 25 years' experience in the field of substance abuse, working directly with drug and alcohol abusers. He has given advice to schools and colleges as well as being involved in training for teachers, health workers, police officers and other professionals. He regularly lectures on substance misuse topics at UK universities. He lives in Hampshire, UK. Graeme Nice has worked in the fields of counselling, substance misuse and blood-borne diseases for over 20 years. He is Deputy Team Coordinator of an NHS substance misuse team in Hampshire, England, where he holds a caseload of drug clients. He has qualifications in counselling, health education and teaching.