On May 25, a store clerk in Minneapolis called the police because he suspected that Floyd had paid for a pack of cigarettes with a counterfeit $20 bill. But the store owner later said: “Most of the times when patrons give us a counterfeit bill, they don’t even know it’s fake.” The call should have started an investigation; that’s not what happened to Floyd.

Instead, within minutes of the police officers’ arrival, Floyd was facedown on the street, …