Inside Prison: The Effects of a Blanket Ban on New Psychoactive Substances
研究利用英格兰和威尔士所有监狱的新数据集，评估全面禁止新型精神活性物质的效果，发现禁令减少了毒品供应但短期内增加了囚犯间的暴力和自残行为，强调需结合戒毒治疗和心理健康服务。
Abstract Prisons are central institutions in the criminal justice system, yet limited data have impeded a systematic analysis of their internal dynamics. We compile a novel, comprehensive dataset covering all prisons in England and Wales to evaluate the effects of a UK-wide ban on new psychoactive substances—potent synthetic drugs designed to circumvent regulation and readily trafficked into custodial settings. We first document the diffusion of these substances across the prison system and a strong correlation with rising violence. Using a difference-in-differences strategy, we find that the ban produced a sustained reduction in drug availability but also a short-term increase in both interpersonal violence and self-harm among inmates. These findings underscore the complex trade-offs involved in supply-side interventions within high-risk environments. Effective policy responses in such settings should integrate demand-side measures—such as addiction treatment and mental health services—to mitigate unintended harms and improve institutional safety.