Under the guise of fighting crime, Sao Paulo has rolled out the world's largest facial recognition system operated by a city. India, China, Hong Kong and the United Kingdom have introduced similar technologies under vague legal frameworks. But no city has embraced surveillance on the same scale as Sao Paulo, making it the world's biggest "Big Brother". The artificial intelligence system, known as Smart Sampa, is now at the centre of a growing scandal after being accused of racial profiling. Repo