The UK has the world’s highest density of CCTVs, which are mainly used as tools to fight crime. But now an “international research network” called The Campbell Collabaration claims the 4.2 million cameras installed in that country almost have no effect. A pattern seems to slowly emerge.
In collaboration with the British government, the organization summarized and analyzed a total of 44 different studies related to the topic, which were released in the last years (mostly in the UK) and are said to be scientifically relevant and valid. The report in full can be found here [PDF].
The result: CCTVs only have a slight effect as far as lowering the overall crime rate is concerned. As far as violent crimes go, the cameras even have no effect whatsoever. The report says CCTVs can only be labeled effective when used in car parks (where they lower the crime rate by about 50% in average).
The Campbell Collabaration also says that CCTVs installed in the UK are more effective in fighting crime than those used in other countries. For some reason, the organization recommends to keep using the cameras, but with a much narrower focus, i.e. to reduce vehicle crime.