This publication aims to provide relevant information to policy makers about the rationale and the existence of a variety of practices for treatment and care for people with drug use disorders who come into contact with the criminal justice system. One of its aims is to help criminal justice actors understand how treatment works and treatment actors how the criminal justice system works. More importantly, it aims to discuss opportunities to bring drug use disorder treatment and criminal justice systems into alignment and to help readers understand the multiple possible perspectives regarding this cooperation.