The important work in this volume tells us some powerful truths. It has long been clear that law enforcement has critical roles to play in protecting the health of the public, and that law enforcement entities have legitimate concerns of public safety, security, and protection. That these roles have led to a broad array of responses to substance use and substance users, which have ranged from harmful to helpful, has also been clear. But in the research and policy pieces brought together here by Nick Crofts and Nicholas Thompson and colleagues, a new paradigm emerges with the potential to have real impacts on key shared goals. Harm reductionists seek to see declines in the health and social consequences of substance use, including reductions in new HIV infections that will be so key to the trajectory of HIV epidemics in much of the world. Law enforcement seeks to see declines in crime, in insecurity, and increases in public safety. Both groups, and all of society more broadly, need to seek declines in unnecessary detention, incarceration, and the destruction of young lives which the use of detention for substance use has wrought. The new paradigm suggests that these goals are not inherently antagonistic–and indeed, are powerfully synergistic. How?