This introduction offers an overview of how the rise of police-worn body cameras and community members recording the police has important implications for the future of proof, privacy, civil rights protection, and violence prevention. The book begins by taking readers onto the streets of West Baltimore, where body cameras now are widely deployed throughout the force, and where community members who deeply distrust the police have cell phone cameras ready to record the cops. The search for a missing shooter— and a bleeding victim—in a community that burned with fires and protests after the death of Freddie Gray captures the daunting needs and mistrust that the recording revolutions aim to address. Even people with strong fear and loathing of the police need someone to call in their hour of need. The hope is that the cops and the public will behave better if they know they are recorded, protecting civil liberties, safeguarding both sides from false claims, and reducing the risk of escalation to violence. This book explores the scientific findings behind these hopes and the evidentiary, privacy, public disclosure and civil rights implications of recording almost all that cops see and do.