Non-lethal weapons take many forms – from rubber bullets and pepper spray to electroshock and long-range acoustic devices – and are intended to temporarily disrupt the operation of the human body without causing permanent injury. Consequently, their proponents argue that these weapons are ethical, legal, and humane, and they have become widely used by police officers and military forces to subdue individuals and control crowds. Social scientists, historians, legal scholars, and activists have long challenged the use of non-lethal weapons in policing and war. Until now, little scholarly attention has been paid to the social, historical, and legal relations that animate the concept of non-lethality, nor is there a comprehensive account of how the concept has achieved social and political acceptance. Disarming Intervention tells the story of how the concept of non-lethality emerged in a series of nineteenth-century legal codes that governed the conduct of international hostilities, and how it continued throughout the twentieth century to legitimate US-led armed conflicts as ethical, legal, and humane. Seantel Anaïs unpacks these issues by tracing the social, historical, and legal legitimization of non-lethality in the United States and in armed interventions abroad. Disarming Intervention shows in detail how it came to be that an idea forever changed the relationship between contemporary weapons of armed conflict and war’s constitutive objective to produce irreversible injury and death.