There are fundamentally two ways you can experience the police in America: as the people you call when there's a problem, the nice man in uniform who pats a toddler's head and has an easy smile for the old lady as she buys her coffee. For others, the police are the people who are called on them. They are the ominous knock on the door, the sudden flashlight in the face, the barked orders. Depending on who you are, the sight of an officer can produce either a warm sense of safety and contentment or a plummeting feeling of terror.