From speed RADAR guns to high tech riot gear, the role of technology in policing is always evolving. Police departments around the world are always looking for new technologies to help them monitor and protect their communities. One of the areas where police departments always need as much help as possible is in monitoring. Police can't prevent crimes or intervene if they don't know that they're happening, but watching the community is time-intensive work – as much as they may try, they can't be everywhere at once. Two of the most significant advances in this area in recent years has been the wide implementation of CCTV cameras and, more recently, facial recognition software.

Qiu Rui, a policeman in Chongqing, was on duty this summer when he received an alert from a facial recognition system at a local square. There was a high probability a man caught on camera was a suspect in a 2002 murder case, the system told him. The depth, breadth and intrusiveness of China's mass surveillance may be unprecedented in modern history The city's surveillance system scans facial features of people on the streets from frames of video footage in real time, creating a virtual map of the face. It can then match this information against scanned faces of suspects in a police database. If there is a match that passes a preset threshold, typically 60% or higher, the system immediately notifies officers.

Qiu Rui, a policeman in Chongqing, was on duty this summer when he received an alert from a facial recognition system at a local square. There was a high probability a man caught on camera was a suspect in a 2002 murder case, the system told him. The depth, breadth and intrusiveness of China's mass surveillance may be unprecedented in modern history The city's surveillance system scans facial features of people on the streets from frames of video footage in real time, creating a virtual map of the face. It can then match this information against scanned faces of suspects in a police database. If there is a match that passes a preset threshold, typically 60% or higher, the system immediately notifies officers.

Authorities argue cameras reduce crime and increase public safety, but some civil liberty groups say such systems are open to abuse and can be used to monitor political critics. It is increasingly difficult for citizens to protect their privacy in public spaces. This has led San Francisco to become the first American city to ban the police and other law enforcement agencies from using facial recognition technology software.