What are citizens of a free country willing to tolerate in the name of public safety? Jon Fasman journeys from the US to London — one of the most heavily surveilled cities on earth — to China and beyond, to expose the legal, political, and moral issues surrounding how the state uses surveillance technology. Automatic licence-plate readers allow police to amass a granular record of where people go, when, and for how long. Drones give the state eyes — and possibly weapons — in the skies. Algorithms purport to predict where and when crime will occur, and how big a risk a suspect...