Among the new tools modern technology has thrown up to law enforcement agencies, the digital camera embedded in the cellphone, the phone cam,appears to hold potential. Last year’s incident in Sweden, when a teenager attempting to rob a grocery shop was caught and sentenced on the basis of phone cam pictures, is a case in point.Phone cams have the advantages of portability and confidentiality. It also enables the transmission of images to other devices like cellphones or computers in seconds. As cellphone use gets cheaper, the number of owners of phone cams will also rise. This, in turn, will enhance the possibility of bystanders recording digital images of criminal activity without wrongdoers being aware of it. These images can be transmitted anonymously to the police without the sender’s identity being revealed. Given the reluctance of most people to come forward and provide information to the police, this aspect could prove to be a blessing in disguise.While there is no legal problem regarding the admissibility of digital images in criminal proceedings per se, there is some difficulty in establishing the authenticity of such evidence. In order to effectively use digital images in a court, it is necessary to prove that they are in their original condition. Digital images produced as evidence can be assailed on the ground that they have undergone change or have been manipulated and hence rendered unreliable. In a traditional media like film photography, although the image can be manipulated it is impossible to conceal the alterations completely. In contrast, a digital image is a numerical representation that is recorded simply as a series of binary digits, either one or as zero, on an electronic sensor which is made of light sensitive element. Because the digital image is represented as a series of zeros and ones in computer memory it could be altered like any other data with ease. Further it is possible to make an exact copy of a digital image that would be difficult to distinguish from the original. Due to this characteristic it is possible to make subtle alterations and even alter the sequence of events to show them in a non-chronological or distorted chronological order. This raises questions about the reliability of such images in a legal proceeding. Of course, all forms of evidence raise question of authenticity, so digital images are no exception. The Best Evidence Rule requires that the authenticity of documents and images should be proved beyond doubt in any court proceeding. This requirement is recognised in almost all legal systems. Yet, in the digital medium, the same image is an original as well as a duplicate. In relation to an image captured by means of a digital camera, the closest which can be deemed to be original can be at best a digital file representing the image which is stored in a memory chip the moment the image is captured. However no image file will be retained in the camera chip itself due to limitations of storage capacity and the captured image will be transferred to another form of storage and the memory chip in the camera overwritten with the next image. Thus the original image, strictly speaking, is destroyed once it is overwritten. Given this, it is difficult to detect fabricated evidence and also to maintain the distinction between an original image and a copy, which becomes a contentious issue in the digital medium.Digital images do, however, have certain advantages. For instance, it has a time stamp that indicates the exact time of a particular event. Also, the destruction of all the digital copies will be difficult since these devices have the tendency to repetitively make copies for transmission, storage, and so on, using data recovery tools. To deal with the problems posed by digital images and to convince courts about their authenticity, investigators must be made familiar with the fundamentals of digital forensics. The trustworthiness of digital evidence is a critical question that they must consider. Once the digital evidence has been captured, protecting its digital integrity is equally important. All this points to the urgent need to evolve best practices for handling digital evidence and maintaining the ‘chain of custody’. Not only investigators, but magistrates and prosecutors should be exposed to this new disciplinez. Capacity building in digital forensics then is a major challenge which policy makers will have to address in the near future.The writer is secretary, Union ministry of law and justice
