Closed-circuit television (CCTV) surveillance cameras are widely used in policing, but that use is controversial. The United Kingdom (UK) government has described CCTV as “vital” for detecting offenders (Porter 2016), while the Washington, DC, Metropolitan Police Department (2007, p 2) argued that it is often “invaluable to police investigations”. On the other side of the debate, the campaign group (Liberty 2016) argued that extensive use of CCTV “poses a threat to our way of life” and that “widespread visual surveillance may well have a chilling effect on free speech and activity”. Similarly, the American Civil Liberties Union claimed that public CCTV surveillance creates “an almost Orwellian potential for surveillance and virtually invite[s] abuse” (Steinhardt 1999).

In the academic literature, there has been discussion of how CCTV fits into broader conceptions of surveillance (Hier 2004; Koskela 2003) and the extent to which it increases or changes the nature of state or corporate power over citizens (Fyfe and Bannister 1996; Norris and Armstrong 1998). Concerns have been raised that CCTV surveillance may restrict the diversity and vibrancy of life in public spaces (Bannister et al. 1998), or contribute to the exclusion of some groups in society (Reeve 1998). There has also been political debate about the proper balance between ensuring the effectiveness of CCTV and protecting the privacy of citizens (Sheldon 2011).

How Might CCTV Help Crime Investigations?

Before turning to the research questions addressed in this study, it is necessary to consider exactly how CCTV might provide useful evidence in a criminal investigation.

A criminal investigation can be thought of as a series of questions: who was involved in an incident, where did it happen, what happened, when did it happen, why did it happen and how were any offences committed, known as the ‘5WH’ investigation model (Cook et al. 2016; Stelfox 2009). CCTV may be useful in answering at least two of these questions: what happened and who was involved (La Vigne et al. 2011).

A good-quality recording could potentially allow investigators to watch an entire incident unfold in detail, providing information about the sequence of events, the methods used and the entry and exit routes taken by the offender. Even if this is not possible, CCTV may be useful in corroborating or refuting other evidence of what happened, such as witness testimony (College of Policing 2014). Recordings may also provide information that investigators can use to contextualise other evidence (Levesley and Martin 2005).

CCTV may assist in identifying who was involved in a crime either directly, as when a suspect is recognised by someone viewing the recording, or indirectly, such as when the recording shows a suspect touching a surface from which police are then able to recover forensic evidence (Association of Chief Police Officers 2011). Images can also be used to identify potential witnesses (La Vigne et al. 2011, p 27). CCTV may be less useful in answering some of the other 5WH questions. For example, even a good-quality recording may shed little light on why a crime was committed.

In order for CCTV to be useful in answering investigative questions, certain circumstances are required. There are few legal restrictions on the ability of police officers to use CCTV recordings of public places during investigations. In the UK, for example, operators of camera systems can provide recordings to the police without a warrant (Information Commissioner’s Office 2015). In the United States (US) a similar system operates, as long as the recording is of a place in which people do not have a reasonable expectation of privacy (Chace 2001). As such, the limiting factors on the use of CCTV are likely to take other forms.