Edge of the Knife is the first study to investigate police violence and accountability in the United States, Latin America, and the Caribbean. Paul Chevigny, author of the classic Police Power, examines the use of torture, deadly force, and less drastic forms of violence in six major urban centers in the Americas.

Chevigny searches for the sources of official violence - and for ways of controlling it. He compares military and community models of policing. He explores the connection between police violence and official corruption. Finally, Chevigny examines the effectiveness of criminal and civil courts, civic administrations, civilian review boards, internal controls, external auditors, and pressure from international human rights organizations in deterring police violence.

Ultimately, he argues that the way in which criminal matters are patrolled and investigated is reproduced in the city's social order. When citizens have little confidence in their government and do not participate in it or look to it for protection, they turn to violent self-help. When their sense of powerlessness combines with an increased fear of crime they are more willing to lend their public support to extra-legal violence by the police.

Conversely, persistent government action against crime, including accountability for police violence, discourages vigilantism as well as official violence.