We are testing a new beta website for gov.scot go to new site

The Effectiveness of Public Space CCTV: A Review of Recent Published Evidence Regarding the Impact of CCTV on Crime



How effective is CCTV?

The 'effectiveness' of CCTV must be considered in light of its intended purpose, as each individual project is installed to serve its own purpose. That said, the rapid spread of CCTV across Britain over the last decade can largely be attributed to claims that have been made regarding the effectiveness of CCTV in terms of crime reduction, and because of this, CCTV evaluations have traditionally focussed on its impact on crime. This review has addressed the most recent evidence with regards to crime deterrence effects, crime displacement effects, the impact on crime detection, and the contributions of evidence captured on CCTV to the process of investigation and prosecution within the criminal justice system. Notably, very little research into the effectiveness of CCTV has been conducted since the year 2000.

Overall, it would seem as though the impact of CCTV on crime has been variable. It would appear that the degree to which CCTV can be deemed 'effective' is dependent on its suitability as a crime prevention intervention and this, in turn, depends on the nature of the crime problem to begin with, and characteristics of the area in which CCTV is installed e.g. whether street lighting is yellow sodium or newer white street lighting which gives better CCTV images at night. Furthermore, the belief that CCTV alone will solve the problem of crime is unrealistic. It has been shown that there are many other factors that are likely to mediate the effect CCTV has on crime including police resources, training and level of efficiency of CCTV operators, and the level of communication between these groups. Here the evidence is summarised, and attempt is made to draw some conclusions relating to each of the four objectives based on these findings.

Crime deterrence

The issue of crime deterrence as a potential outcome of CCTV is particularly difficult to evaluate as researchers are faced with the problem of assessing crime that may have been observed, had CCTV not been installed in the area. The findings of Griffiths (2002), and Mazzerolle et al (2002) suggest that CCTV may be effective in deterring crime, and in the case of the latter study, anti-social behaviour, but only initially upon installation, where recorded instances of crime and anti-social behaviour in both studies gradually increased again with time. It has been speculated that the media may have a role to play in this trend where, initial intensive media coverage may result in an immediate deterrence of crime upon installation, but where a decrease in media attention over time will also lead to diminished deterrence effects. This in theory seems a reasonable suggestion and thus, calls for future research attention.

Gill and Spriggs (2005) have conducted the largest evaluation of its kind to date, covering the impact of CCTV on crime in 14 English towns and cities. On the face of it, the results of this study suggest that CCTV fails to effectively deter crime, where the rate of recorded crime decreased following the installation of CCTV in only one of the target sites evaluated, and in none of the city centres covered in the study. Interestingly however, the most significant and desirable effect of CCTV was found for a train station car park where crime decreased by 73% (from 794 to 214). This result is arguably unsurprising in light of the previous repeated finding that CCTV is most effective in deterring vehicle crime, and crime in smaller and less complex areas. Thus, it becomes clear that the effectiveness of CCTV in terms of crime deterrence is largely dependent on its suitability to the type of crime it is to prevent, and the area in which it is installed.

Further evidence from studies adopting altogether different methods in investigating the potential crime deterrence effects of CCTV does exist. Gill et al (2006) for example, conducted focus groups with convicted murderers with the aim of uncovering whether CCTV may have deterred them from committing their crimes. Although anecdotal in nature, the evidence from this study generally reflects what has already been discovered in objective evaluations and previous reviews of the literature - that the deterrence effects of CCTV appear largely minimal, and the likelihood of crime deterrence effects are diminished further when the offender in question is under the influence of alcohol.

Crime displacement

Gill and Spriggs (2005) found no significant evidence of spatial displacement of crime to a surrounding control area. Interestingly however, these authors did find evidence to suggest that spatial displacement can occur on a smaller scale than perhaps previously thought possible where, for one of the target sites in their study, a decline in recorded crime was noted for the area within 100 metres of the cameras. Griffiths (2003) found evidence of an initial diffusion of benefits in the control area in the form of a 22% decrease in recorded crime during the first 12 months following the installation of CCTV in the target area. Again, the suggestion was put forward by the author that increased media interest upon installation of the project may have been responsible for this initial effect but, once offenders had worked out where the cameras were, with time, this effect wore off.

The recent evidence regarding the topic of potential displacement effects is minimal and therefore, does not add much insight to this already inconclusive topic. It does however, appear that in reality, spatial displacement of crime does not present as much of a problem as it could in theory. Anecdotal evidence from focus group discussions with offenders in Gill et al (2006) does indeed support this assumption where displacement effects were said to be only partial. One new and interesting idea however, to have emerged from this study, was that displacement to a different type of crime following CCTV installation may be an issue of concern. Traditionally, there has been a bias in attention towards spatial displacement in previous CCTV evaluations. The issue of displacement to another type of crime should therefore, be investigated further in future research.

Crime detection

The problem in using recorded crime statistics as a measure of the effects of CCTV is that an increase in such figures could reflect improved crime detection, as opposed to an actual increase in crime (and thus, failure in terms of crime deterrence). Two recent studies that have supplemented recorded crime statistics with other crime outcome measurements have resulted in interesting findings. Farrington et al (2007) found that victimisation survey data did not significantly change for either the target area of Cambridge or the control area, whereas police-recorded crime statistics decreased by 15% in the control area compared to the target area following the installation of CCTV. Similarly, Sivarajasingham et al (2003) observed an overall decrease in assault related emergency department attendances, and an overall increase in police recorded violent crime statistics across the five target areas covered in their study. These findings therefore, suggest that CCTV is more effective in terms of improved detection of crime, than it is in terms crime deterrence effects. The findings of Sivarajasingham et al (2003) are particularly interesting given that they relate specifically to violent crime. The repeated finding that CCTV has little success in deterring violent crime may lead to the acceptance that CCTV does little to improve instances of violence. It would appear however, that CCTV may benefit the issue of violent crime through increased rates of detection, if this in turn is followed by a quick police response. The extent to which this potential benefit of increased detection is realised in reality however, has been discussed as being dependent on a variety of factors beyond just the quality of CCTV itself.

Interviews with the police such as those conducted by Owen et al (2006), and Levesley and Martin (2005) have provided an insight into the benefits resulting from the increased detection of crime through CCTV. Such benefits were said to include the following: a reduction in time spent on the investigation process, information to guide the deployment of officers, and the prevention of minor incidents escalating into more serious ones. Owen et al (2006) placed an economic value on these benefits at an estimation of savings up to £1,601,600 a month. This is an issue that requires further future attention. Nevertheless, regardless of its potential economic value, the anecdotal evidence to suggest CCTV is a resource valued highly by the police, due to the contributions it makes to their work in terms of increased crime detection, is strong.

The use of evidence in the investigation and prosecution process

The most striking finding from police interview data collected by Owen et al (2006), and Levesley and Martin (2005) is the considerable amount of time that can be saved during the investigation process due to the use of evidence found in CCTV footage. This is predominately due to an increase in early guilty pleas in the face of strong video evidence through which Owen et al (2006) have attributed an estimated economic annual saving of up to £8,345.18. Nevertheless, the extent to which these benefits are realised is a complex process dependent on many other factors. Indeed, many of the officers interviewed by Levesley and Martin (2005) expressed dismay and amazement at the difficulty the courts had with showing images. It was reported that many are still only equipped to accept video tapes. Advances in the digital technology behind many CCTV systems today therefore, means that it is likely evidence from CCTV footage is not yet being used to its full advantage.

Davies and Thasen (2000), in their psychological laboratory experiment, found that recognition of an unfamiliar individual from CCTV footage is a highly fallible process. Indeed the high rate of identification errors observed among participants in this study has been replicated many times before in previous investigations of human face perception ability. These authors therefore, concluded that the practice of inviting individuals unfamiliar with the alleged offender to compare the appearance of a CCTV image with that of the defendant should be avoided. Bruce et al (2001) however, found that familiarity has a significant positive effect on the accuracy of person identification, particularly where deep or social processing of the face has occurred. On the basis of this finding, Bruce et al (2001) promote the circulation of CCTV footage in the media as an attempt to provoke identification by members of the public that may be familiar with the offender. Therefore, while anecdotal evidence of the actual contributions CCTV makes to those working in the criminal justice system is available in the form of interview data, evidence from psychological theory and experimentation has allowed for suggestions to be made as to how evidence from CCTV footage should be used in the future to ensure the most just and reliable outcome for the criminal justice process.

Further benefits of CCTV

The effectiveness of CCTV has traditionally been evaluated in terms of its impact on crime. Nevertheless, there is some evidence to suggest that CCTV may increase public feelings of safety, although, overall the reality of this issue is not yet clear due to conflicting findings. There is an argument to be made however, that if CCTV is in fact successful in making people feel safer, then it is in this sense effective, regardless of any actual impact it has on crime. Furthermore, consistent with the argument that the installation of CCTV has little to do with crime, is evidence from Mackay (2003) suggesting that CCTV systems are largely supported due to benefits unrelated to crime such as management capabilities, satisfaction of public demand, and positive effects on city centre economies. In conclusion, CCTV appears to result, not only in increased crime detection and evidence useful to the process of investigation and prosecution, but also in a wide range of other benefits beyond an impact on crime. It has been argued that these 'extra' benefits are highly valued by those working alongside CCTV and thus, should not be overlooked when the effectiveness of CCTV is considered.