This article highlights the problem it names as ‘interventionitis’; the tendency of policymakers to treat enduring, systemically generated problems with limited interventions that are insufficient or inappropriate for the intended improvement. We outline three typical features of interventionitis; overconfidence in these quick fixes, the iatrogenic effect of unintended harms caused by such interventions, and the focus on surface-level rather than systemic change. We then present three cases of interventionitis in the contemporary criminal justice system of England and Wales: the placement of police officers in schools, drug testing on arrest, and the peer-led induction programme in prisons. We support an alternative approach that adds consideration of inequalities, institutions and interactions alongside interventions. Interventionitis can be observed across the English and Welsh criminal justice system. It limits the prospects for taking steps to reduce the harms caused by crime and its control.