In the U.S., where police departments and the F.B.I. are adopting comparable technology, facial recognition has prompted congressional debates about privacy and policing. The courts have yet to clarify when a city or a company can track a person’s face. Under what conditions can biometric data be used to find suspects of a crime, or be sold to advertisers? In Xi Jinping’s China, which values order over the rights of the individual, there are few such debates. In the city of Shenzhen, the local government uses facial recognition to deter jaywalkers. (At busy intersections, it posts their names and I.D. pictures on a screen at the roadside.) In Beijing, the government uses facial-recognition machines in public rest rooms to stop people from stealing toilet paper; it limits users to sixty centimetres within a nine-minute period.