London thugs will set up face recognition systems on streets, to check the face of each person that passes by.

They say that each system will have a specific list of suspects' faces to look for. However, today's face recognition systems are inaccurate. If a suspect in the list is black, the system is likely to trigger on other blacks who resemble the suspect. The thugs will stop them and identify them, and determine that they are not that suspect. This does not imply they will be allowed to proceed down the street. They could be searched, arrested, whatever.

In effect, these systems can provide an excuse to stop large numbers of people "for cause".

It doesn't go all the way to China, but it takes a big step in that direction.