• Center for Problem oriented policing

POP Center Responses Video Surveillance of Public Places, 2nd Ed. Page 2

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How CCTV Aims to Prevent Crime 

A CCTV system is not a physical barrier. It does not limit access to certain areas, make an object harder to steal, or a person more difficult to assault and rob, yet it is still an example of situational crime prevention. It does have some crime prevention capacity in the right situations. Although CCTV has many functions, the primary preventative utility is to trigger a perceptual mechanism in a potential offender. It seeks to change offender perception so the offender believes if he commits a crime, he will be caught. In other words, CCTV aims to increase the perceived risk of capture, a factor which, assuming the offender is behaving in a rational (or limited rational) manner, will de-motivate the potential offender.6 For this crime prevention process to succeed, two elements must exist: 

  1. The offender must be aware of the cameras’ presence.
  2. The offender must believe the cameras present enough risk of capture to negate the rewards of the intended crime. 

Consider the first element. If, for example, a CCTV system is initiated to stem a perceived increase in disorder crime in a town center, the crime prevention mechanism requires that potential offenders know they are being watched. Evidence suggests that even though implementers install a system, have a publicity campaign, and place signage, there is no guarantee the population will be aware of the cameras. In Glasgow, Scotland 15 months after 32 cameras were installed in the city center, only 41 percent of those interviewed were aware of the cameras.7 These findings are similar to other research that found only one-third of respondents were aware they were within the vision of a public-street CCTV system.8 

Not only are there limitations with the public’s perception of the location of cameras, the second element (the presence of cameras affecting offenders’ perception of risk) is not guaranteed. In theory, CCTV should provide the capable guardianship necessary to prevent a crime, but this concept requires that offenders demonstrate rationality in their behavior. There is certainly the suggestion, and some qualitative evidence, that potential offenders who are under the influence of alcohol or drugs may not care or remember that they may be under surveillance.9 This may be a factor in the reason CCTV appears to be more effective in combating property crime than disorder and violent offenses. However, as the media and social media increase their coverage of minor crimes caught on home surveillance cameras, potential offenders may recognize the increased risk of being caught for these crimes and think twice about committing them.10 

An important consideration in the effectiveness of a surveillance technology is the type of crime to be tackled because this impacts criminals’ ability to adapt. Although a CCTV system may reduce the likelihood of burglary at a commercial location within the range of the camera, there is some evidence that drug markets can continue operation in the presence of CCTV by changing their operating practices. For example, at one location some offenders met and discussed business in the cameras’ presence but concluded the transaction at another site.11 In other CCTV areas, however, drug crime that could not successfully relocate or adapt to the cameras was eradicated. 

Fake cameras have been employed in some instances. In one instance, crime was reduced on public buses after the installation of both active and dummy cameras onboard a number of buses (indeed crime reduced on more buses than the ones fitted with any cameras, a concept known as a diffusion of benefits).12 It is therefore possible that fake cameras could achieve the same preventative aim as active systems. However, if users of the space under surveillance are led to believe—through signs, for example—that they are being watched 24 hours a day and an incident occurs, the misrepresentation of a form of guardianship may have liability implications. 

There is a second mechanism whereby CCTV has the potential to reduce crime. The cameras may be able to assist in the detection and arrest of offenders. This crime prevention mechanism requires that police can respond in a timely manner to any significant incidents identified by camera operators, and that the local criminal justice system can pursue the offenders’ conviction. This mechanism will work if incarcerated offenders are prevented from committing further crimes within the CCTV area (or other local area). Although there may be some initial crime reduction due to the installation and publicity of a new system, offenders may soon learn what types of incidents elicit a police response and the speed of that response. The availability of local resources is therefore a factor in the success of this mechanism. 

The desire to catch an offender in the act is often the rationale behind the placement of hidden cameras, as was used by police in New Orleans.13 Undoubtedly CCTV evidence is convincing, though CCTV’s ability to reduce overall crime levels through detection (rather than prevention) is less convincing and arguably a less effective way of impacting crime. For this mechanism to be effective, the implementer must believe arrests are the best way to solve a crime problem. There is some evidence from Australia that increasing arrests can have a short-term benefit, but the benefit fades in the long term without a more preventative policy.14, †

† It could also be argued that this worked only in a city that was geographically isolated, such that a rapid replacement of prolific offenders was not possible.

A third, more general mechanism by which CCTV may reduce crime is through an increase in collective efficacy. Welsh and Farrington15 argue that if residents see CCTV cameras being installed in their neighborhood, this will signal to them a degree of investment in, and efforts to improve, their local area. They argue that this might lead to greater civic pride and optimism, and, as a result, lead to an increased level of informal social control among the local people. A counter to this argument is that overt cameras may instead lead to a neighborhood being labeled as high-crime, accelerating the process of social disorganization. 

A fourth mechanism through which CCTV may reduce crime is through increased awareness on the part of potential victims. Seeing CCTV systems can remind individuals to take other security precautions such as locking car doors. The presence of CCTV systems may not only remind individuals to take precautions but may also make them more likely to do so because they do not want to be shamed for being seen not taking precautions. Finally, cautious people might also be drawn to areas where CCTV is present reducing their chance of victimization.16

Other Benefits 

A number of other benefits, beyond a reduction in crime, may be accrued from a CCTV system, including: 

  • Reduced fear of crime
  • Aid to police investigations
  • Provision of medical assistance
  • Place management
  • Information gathering
  • Diffusion of benefits 

The following section describes these potential benefits in more detail. 

Reduced Fear of Crime 

Numerous studies have tried to determine if the presence of cameras in public places reduces fear of crime in people who use the area. These studies, many of which interviewed people in the CCTV area, have examined whether consumer buying has increased in areas with new CCTV systems. The general argument is that the area will benefit from a positive economic impact when people feel safer. The findings are mixed but generally show there is some reduced level of fear of crime among people in CCTV areas, but only among people who were aware they were in an area under surveillance. Most studies exploring the perception of surveillance areas found that less than half the interviewees were aware they were in a CCTV area. In addition to differences based on awareness, the impact of CCTV on fear of crime may differ based on the gender of the individual. One study noted fear of crime was reduced for men and not for women when CCTV cameras were present.17 Reduced fear of crime in an area may increase the number of people using the area, hence increasing natural surveillance. 

Aid to Police Investigations 

Regardless of the potential for a CCTV system to have a role in crime prevention, it can still make a contribution in a detection role. There are numerous examples of CCTV tapes aiding in an offender’s conviction. Camera footage can also help identify potential witnesses who might not otherwise come forward to police, help investigators narrow the time window when a crime occurred, establish a sequence of events, capture images of getaway vehicles, and help locate weapons used during the crime.18 CCTV camera evidence can be compelling, though issues of image quality are a factor if CCTV images are used for identification purposes. If the cameras record an incident, and police respond rapidly and make an arrest within view of the camera (and the offender does not leave the sight of the camera), the recording of the incident can help investigators gain a conviction, usually through a guilty plea. The potential to assist in police investigations may also drive offenders away from committing offenses that take time, as they run a greater risk of capture. 

Provision of Medical Assistance 

As a community safety feature, CCTV camera operators can contact medical services if they see people in the street suffering from illness or injury as a result of criminal activity (such as robberies and assaults) or non-crime medical emergencies. The ability to summon assistance is a public safety benefit of CCTV. In addition to summoning assistance, when live feeds are being monitored, operators can direct responding personnel to the individual once they are at the scene and can help them avoid any potential dangers.19 Squires found that police are called about 10 to 20 times for every 700 hours of observation.20 

Place Management 

CCTV can be used for general location management. The cameras can be used to look for lost children, to monitor traffic flow, public meetings, or demonstrations that may require additional police resources, or to determine if alarms have been activated unnecessarily thus removing the need for a police response. Actively monitored CCTV systems also allow for spotting a crime that is occurring before someone calls 911, promoting a quicker response.21 Quicker responses at locations may also reduce the escalation of crime as it happens.22 Some police commanders claim that assaults on police have reduced because the cameras allow them to determine the appropriate level of response to an incident, either by sending more officers to large fights, or by limiting the number of officers to a minor incident and avoid inflaming the situation.23 

Information Gathering 

Cameras can also be used to gather intelligence and to monitor the behavior of known offenders in public places (such as shoplifters in public retail areas). Camera operators often come to know the faces of local offenders, and the cameras become a way to monitor their movements in a less-intrusive manner than deploying plainclothes police officers. For example, officers in one city were able to gather intelligence on the behavior of individuals selling stolen goods. This intelligence was gathered remotely by CCTV cameras and enabled police to interdict in an organized and coordinated manner.24 Although intelligence gathering is a potential benefit of CCTV, the use of intelligence gathered from CCTV to control public order through surveillance is perceived by some to be a threat to civil liberties.25 

Diffusion of Benefits‡

 See Problem-Solving Tools Guide No. 10, Analyzing Crime Displacement and Diffusion for further information.

Current research has also considered the distinct possibility that if offenders are aware and cautious in the presence of cameras, they may be unaware of the extent of the cameras’ capabilities. As a result, they may curtail their criminal activity in a wider area than that covered by the camera system. Studies have produced mixed results but at least some studies find small crime-reduction benefits in areas beyond the camera range, also known as buffer zones.26 In effect, this extends the value of the cameras beyond their area of operation, a process criminologists call a diffusion of benefits.27

Unintended Consequences 

Although not discussed in the literature of companies that sell cameras, CCTV systems may also have some unintended consequences. These include: 

  • Displacement
  • Increased suspicion or fear of crime
  • Increased crime reporting 

These possibilities are discussed in the following sections. 


§ See Problem-Solving Tools Guide No. 10, Analyzing Crime Displacement and Diffusion for further information.

There are many different types of displacement. Instead of a reduction in offenses, you may see offenders react by moving their offending to a place out of sight of the CCTV cameras. This is an example of spatial displacement. The evaluations in Appendix B suggest that spatial displacement can occasionally take place, but—as is the case with the general crime prevention literature28—the amount of crime displaced rarely matches the amount of crime reduced. There is usually a net gain for crime prevention. In all of the studies evaluated for this report, there is not a single example of a complete displacement of all crime from a CCTV area to a neighboring area. When displacement does take place, officers may have to develop new intelligence.29 However, spatial displacement is not the issue many people think it is, and in most of the studies there is little evidence of spatial displacement. 

A CCTV system may also force the criminal fraternity to be more imaginative and to diversify operations. For example, researchers reported that in a London drug market the presence of cameras encouraged the drug market to move to a system where orders were taken by mobile phone and then delivered, and as such “increase the speed and ingenuity of the drug transaction.”30 This is an example of tactical displacement, where offenders change their modus operandi to continue the same criminal acts. Even though this particular introduction of CCTV may not be seen as an unqualified success, that the CCTV system forced a change in behavior is positive. CCTV is likely to have forced drug dealers to adopt a less effective way of conducting business, resulting in a net reduction in crime. 

Increased Suspicion or Fear of Crime 

A second concern is the possibility of a negative public response to the cameras’ existence. In one survey, one-third of respondents felt that one purpose of CCTV was “to spy on people.”31 In other surveys, some city managers were reluctant to advertise the cameras or have overt CCTV systems for fear they would make shoppers and consumers more fearful. In other words, it is hoped that most citizens will feel safer under the watchful eye of the cameras, but CCTV may have the reverse effect on some people. In one city where camera feeds were open to the public, citizens experienced increased fear of crime because they worried this access would allow potential offenders to observe their habits and routines, making them easier targets.32 

Remember that the primary crime prevention mechanism appears to work by increasing a perception of risk in the offender. With their reluctance to advertise the system, some city managers may be inadvertently reducing the cameras’ effectiveness. By failing to advertise the cameras’ presence, fewer offenders will be aware of the system and so will not perceive an increase in risk. On the whole, however, the public appears to be strongly in favor of a properly managed surveillance system for public areas. 

Increased Crime Reporting 

A third unintended consequence is the possibility that there will be an increase in recorded crime for some crime types. Many offenses have low reporting rates, especially minor acts of violence, graffiti, and drug offenses. CCTV operators are better placed to spot these offenses, and this can actually drive up their recorded crime figures, as happened with narcotics offenses in Oslo Central Train Station.33 Individuals may also be more likely to report a crime if they know it might have been captured on CCTV.34 This is not to say there was an increase in actual crime, just recorded or reported crime. This is a potential outcome, and you may need to prepare other people involved in a future CCTV system of this possibility, especially if the system is going to be evaluated in terms of crime reduction.                                                                                 

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