20% of the world's CCTV cameras are to be found in the UK. The existence of CCTV footage is now an integral part of any criminal investigation. Any police officer reporting a crime is required to establish whether there are cameras positioned locally, and whether any footage has been recorded.
CCTV tapes are seized on a regular basis, whether or not they contain anything useful. The vast majority of footage is recorded in time-lapse in a multiplex format. This means that one tape will often contain footage from a large number of cameras. This footage will not be 'live time' unless an incident has been specifically filmed by the operator.
This causes a number of problems. Criminal incidents, by their very nature, often happen quickly. Footage in time lapse, assuming the camera was pointing the right way, more often than not merely shows 'snap shots' of the incident concerned. Figures can be seen from a distance doing 'something'. This footage will show that some kind of offence has taken place. It is more than useless for the purposes of finding out who did it.
Identification of the suspect is a key part of criminal law. The prosecution is required to prove that a crime has been committed, and that the person charged was the person who did so. Identification is therefore a complex area. As can be seen above, unless an incident has been filmed live, identification is rarely assisted by CCTV.
Live time CCTV footage often provides compelling evidence. This is very useful should the suspect have been arrested. If not, you are left with the footage to work with. This relies on the line of sight being clear, and the facial features of the suspect being seen. This can often be frustrated by head or facial coverings, and more commonly, the suspect not looking in the direction of the camera. Even if there is good footage of the face, this person still needs to be identified. Pictures are often circulated in police publications with very little success.
CCTV viewing occupies a dis-proportionate amount of police time with very little tangible result. This fact is well known to street criminals. The deterrent effect, as with any negative, is very difficult to gauge. Taking account of this, the question must be asked - Are the powers that be justified in deploying so many CCTV cameras?