Introduction During the past decade, there has been unprecedented investment and expansion of drug treatment services in Britain. Given the emphasis on drug-related crime within contemporary drug policy, the criminal justice system has become a major route into treatment services and much of the investment has occurred there. This is a new development. Historically, the treatment services and the criminal justice system have existed independently of each other with very little overlap and interaction. These changes have been based on the growing evidence base indicating that 'treatment works' and reductions in crime could be linked to treatment (Godfrey et al., 2004; Donmall et al., 2009). From a political perspective, the links between drug treatment and crime reduction have helped to secure the funding and long-term investment to expand services and win public support for this spending. However, this expansion of treatment and the situating of service provision within the criminal justice system have had profound effects on the practice and training needs of drugs workers.