Confusion surrounding the use of digital images as evidence is holding back the technology's potential in environmental health work. EHO and experienced photographer, John Smith, clearly sets out the legal position on digital camera use

The use of digital images in court has been a subject of debate for the Government, and in particular the House of Lords. On the ground meanwhile, enforcement officers have worried about whether or not digital images will be allowed by magistrates and judges, or if they may be thrown out for being open to manipulation or for not being an "original" image.

Fears that pictures taken from digital cameras are inadmissible are totally unfounded. The Home Office requirements for digital enforcement systems specify the camera resolution to be used (approximately 1000 x 1500 pixels), image compression standards for when the image is transmitted to the computer, transmission encryption protocols and standards for storing and archiving images. An authentication code is also required to be added to the image. Pixel resolution at 1.5Mb ensures a reasonable hard copy output of approximately A4 size. Alongside this guidance, the Lords' Science and Technology Committee on Digital Images as Evidence sets out advice and information in its report, as does a government response on digital imaging to the House of Lords.(1,2)

EVIDENCE AND ENHANCEMENT
The committee's report says of digital images that their "weight as evidence will depend on proper authentication and other matters".
It goes on: "In relation to a digital camera, for example, it is probable that the original would be the digital file representing the image which is stored on a memory chip, or series of chips, at the moment that the image is captured. That digital file will immediately be copied to some other form of storage and the memory chip will be overwritten with the next image. This does not represent a problem under the law of England and Wales because if the original of a document no longer exists, copies or even copies of copies are admissible in evidence and it is irrelevant that the original was destroyed. "The fact that a document is a copy goes to its weight as evidence, not its admissibility. It will therefore be necessary for the user to be able to give evidence of the procedures used for generating, processing and storing digital images, so as to be able to prove that the image produced to the court is an accurate copy of the original. But in general, provided it would not prejudice a fair trial, the court is likely to admit the evidence and the judge will direct the jury on the weight they should consider attaching to it.

"Changing the contrast or colour balance of a computer monitor may be considered visual 'enhancement' and is no different from what might be done to an analogue image. However, any alterations which affect the image data, no matter how innocuous, should be treated with caution. Sharpening the outline of an object is a standard option on image-processing software which usually involves changing the contrast at the edge of the image (eg black pixels against grey pixels may become black against white). After sharpening, the object is easier to see, but the image data have been changed."

LEGAL POSITION
The report goes into the current legal position in detail. "Although there is no legislation which expressly covers digital images used as evidence, nor any reported cases in which the fact that an image was collected in digital form was at issue... there is a substantial body of the law of evidence which deals with the problems arising from technological recordings. This body of law will equally apply to digital images. Indeed, witnesses including the Senior Counsel from IBM (Q 263) and solicitors from Bird & Bird (Q 78) regarded the differences between digital images and other evidence as being one of "degree rather than of fundamental kind" (Q 78).

"In criminal cases the position is a little different, as the House of Lords has decided that the provisions of Section 69 of the Police and Criminal Evidence Act 1984 apply to all computer records, whether they are hearsay or not. This means that in criminal cases, any use of a digital image as evidence must be accompanied by the certificate required under Section 69. This certificate, given by a person responsible for the computer system in question, must state that either the computer system was at all times operating properly, or that any defect in its operation was not such as to affect the accuracy of the record...
"The Law Commission has recently recommended the repeal of Section 69 of PACE because it 'serves no useful purpose'. The Law Commission said that it was impractical to certify all the intricacies of computer operation and experience showed that most computer error was either easy to detect immediately or had resulted from human error in data entry rather than from malfunction. With the repeal of Section 69, a presumption of proper functioning would be applied to computers (Evidence in Criminal Proceedings: Hearsay and Related Topics, LAW COM No. 245, June 1997)."

CONCLUSION
In short the report recommends that with a clear audit trail, the user should be able to give evidence of the procedures used for generating, processing and storing digital images, so as to be able to prove that the image produced to the court is an accurate copy of the original. The report concludes:
"We were pleased to find that digital images, which we initially thought might create difficulties for the courts, do not."
Other law enforcement professionals are using digital imaging and the new Police Speed Cameras will use digital cameras that e-mail the results to Police HQ - surely a sign that digital imaging is the way forward.
To read the full text of the Lords' Committee report go to
www.parliament.the-stationery-office.co.uk/pa/ld199798/ldselect/ldsctech/064v/st0501.htm

References
1. House of Lords Science and Technology Committee on Digital Images as Evidence (5th Report, HL Paper 64)
2. Digital Images as Evidence: Government Response (8th Report, HL Paper 121 - Lord Craig of Radley.)

John Smith is a specialist EHO (environmental protection) at Reigate and Banstead Borough Council

What is a digital camera?
It is a camera which comprises an image focusing lens and box with a device to transfer the image into binary code.

What are the benefits?
You can take a photograph, view the image immediately on an LCD screen, print it on a portable printer, download it to a computer and send it back to the office. The image may be e-mailed or placed on a web page.

How do you download pictures onto computer?
The quickest way to download images is to use either an infra-red transmitter or a flashpath adapter. PC cards tend to be found in more expensive cameras and PC drives are often found on laptops and can be installed on PCs. Avoid downloading by cable from camera to PC as this is lengthy and drains batteries

Which kind of camera is best?
For legal purposes it is vital that the images are recorded on a CCD chip capable of resolving 1.5 Megapixels.
Most digital cameras use standard AA or AAA batteries but battery consumption is very high. It is therefore advisable to select a camera where rechargeable batteries can be fitted.

Zoom or fixed lens?
If you intend using the camera for general recording purposes and occasional legal use, then a fixed lens is often better as it is intrinsically more reliable, provides better image quality, is more compact and usually significantly cheaper.

Are digital images as good as photos in print?
The resolution from a 1.5-Megapixel camera provides quality adequate for prints up to 10" x 8" but no more. Three-Megapixel cameras will provide reasonable print quality twice this size. If you require on-site prints, running costs should be taken into account as portable printers are notoriously expensive. For office printing a photo quality printer with at least 600 dpi should be selected. A3 size printers are often not much more expensive than A4 and provide a quick way to print posters Output from digital cameras is more than adequate for web pages and electronic presentations.