Under surveillance

Written by Pauline Norstrom, Chairman, the BSIA CCTV Section

In recent years we have witnessed the widespread adoption of powerful digital video recording systems as the world of surveillance parallels the digitalisation of all aspects of our lives – from the television we watch to the music we listen to. This step change in technology has opened up tremendous opportunities in terms of the capabilities of digital solutions compared to older analogue systems to deal with a wide range of criminal and terrorist threats.
    
Thankfully the practical experience amongst police officers, and others, gathering video evidence from recording systems has moved on since the days when the pictures gathered from CCTV cameras were frequently discovered to be in a poor state. A combination of insufficient cleaning and maintenance, overuse of VCR tapes, inadequate lighting and lax operational procedures often led to problems in identifying potential crime culprits.

Shifting expectations
Of course this is not to say that the move to digital has been smooth sailing. It has also thrown-up some challenges, most notably, ensuring that end users, the judicial system and the police appreciate that digital video evidence is not the same as a tape based recording.
    
Historically, with a standard VCR tape, security managers and the police had the reassurance of being able to physically touch the original. Not so with digital as images have to be taken off the hard drive of a unit and copied onto removable media. For cases where digital images are being used for evidential purposes, it is imperative that proper consideration is given to securing the integrity of the material and that the digital video recording systems comply with the latest British Standards and best practice.
    
In response to the pressing need to ensure that the proper procedures are being followed, and that adequate weight could be given to digital video evidence in the criminal justice system, at the BSIA we produced a Code of Practice for ‘Digital Recording’ systems. This process involved extensive consultation with interested bodies in the UK including the Association of British Insurers, the Law Society, and the Home Office Scientific Development Branch, plus input from police forensic experts. Moving on from this document, which was positively received by stakeholders, we assisted in the development of the new British Standard, BS8495, which also focuses on this critical area and takes on board many of the elements in our original Code of Practice.

Setting the standard
Published at the end of 2007, the landmark British Standard, BS8495, was ratified by BSI less than a year after our Code of Practice. BS8495 delivers invaluable recommendations for the specification, selection, installation and operation of digital CCTV recording systems that generate CCTV images that may be used in a court of law. It is aimed at assisting specifiers, installers, users, insurance companies, police, authorities and purchasing organisations to ensure systems are used more effectively to gather vital evidence.
    
As a starting point BS8495 underlines the necessity of looking at the operational requirements of the CCTV solution before evaluating the clarity of the recording images as the judgement on this will to a large extent be dependent on what the CCTV has been deployed for.
    
When it comes to the quality of digital CCTV images recorded there are a number of factors which can have an impact on the outcome such as the size of the subject in the field of view, lighting, maintenance, image transmission and specification of the camera/lens.
    
Other key areas covered by BS8495 to ensure that digital video evidence stands-up in court include the fitness for purpose of recorded images, the importance of a detailed audit trail, the need to maintain image integrity by preventing unauthorised access, the role of time and date integrity, the considerations associated with effective storage and the export and replay of exported images.

Audit trail
When dealing with digital video evidence a vital concern is the ability to provide a robust audit trail. This should be verifiable and fully documented all the way from the recording of reference images to its presentation in court. Without such a process the validity of the evidence could be called into question.
    
There is also a need to ensure that the integrity of the stored reference image remains by preventing any unauthorised access, this can be by physical or electronic means, while at the same time enabling images to be provided to legitimate third parties such as the police. It is also advisable that the time and date of recording is logged as part of an image’s metadata.
    
Another area, addressed within BS8495, is that of the process of image export. From an evidential point of view there is certainly a need to ensure that the stored reference image remains unchanged even when, for example, an enhanced version of the image is created and that an appropriate audit trial can be provided.

Holding up in court
To reiterate, there is a pressing need for a verifiable, documented, audit trail from the recording of the reference images to its presentation in court and facilities at this juncture for media playback. A serious concern is that unless these audit trails and operator procedures can hold-up under scrutiny in court, the Crown Prosecution Service may not be able to use the image in the first place or defence lawyers will later be able to pick holes in the evidence, potentially jeopardising the case, not to mention wasting police time.
    
Ultimately, we want to see the same confidence in the validity of digital media in the criminal justice system as there is in VHS tape from a traditional VCR, and there is little doubt that BS8495 standard is a significant step towards realising this goal.

For more information
Web: www.bsia.co.uk