Disclosure of Digital Evidence in Rape Trials
This note arises from a hearing by the Commons Justice Select Committee on Disclosure of Evidence in Criminal Trials on 15 May 2018. A transcript is available at: http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/justice-committee/disclosure-of-evidence-in-criminal-cases/oral/83096.pdf and a video at https://www.parliamentlive.tv/Event/Index/13d15d6a-8aa9-40ce-bdf2-3d19777b3af8
Digital forensics practice requires that the entire contents of a personal computer or smart phone be forensically copied and then analysed; the concern is that if all of this material is provided to the defence it will be used for aggressive cross examination about a complainant’s previous sexual history.
For a quarter of a century it has been the practice when dealing with evidence from digital devices such as personal computers that a “forensic copy” is made of the device at as early an opportunity as possible. (The procedures have been updated to deal with smart phones and acquisition from cloud-based services). This is done the several reasons. First, it provides an explicit physical link between a device and the person responsible for it so that there can be attribution of its contents. Second, direct examination of a device is highly undesirable because in the course of it data will get altered; the procedures for making a forensic copy avoid this and in fact all examinations take place on the copy not the original. Third, it is all too easy for individual emails, social media postings, webpages, photographs, et cetera to be subject to forgery. But it is extremely difficult to forge an entire hard disk or memory of a phone. The operating systems create file date and time stamps and many other alterations all the time and it is easy to spot tampering. The forensic image thus provides essential provenance, authentication and continuity .
This procedure is for the benefit of all types of evidence that might be adduced from these sources and for the benefit of both prosecution and defence. In a rape trial, along with any other case, the prosecution may wish to rely on digital evidence as well. In case you are asking yourself – can't they redact the forensic image? The answer is not really, given the technical complexity of the task (existence of temporary back-up files, caches, registry entries etc). The issue was examined extensively in the context of legal professional privilege. There the solution is that an independent lawyer is appointed to identify material which should be redacted.
Turning now to the defence position, the availability of a digital image makes it very difficult for the prosecution to cherry pick evidence. The cherry picking may be deliberate, the result of poor training, or simply “confirmation bias”. The role of the defence is to see if this has taken place. It was these concerns that triggered the current enquiry. The enquiry by the Justice Select Committee is about, among other things, the mechanics of disclosure. Because of the quantity of data to be examined it is unrealistic to expect a prosecution expert or technician to carry out an exhaustive examination of all the devices that might have been seized. This plainly creates a problem for the disclosure regime as it is normally understood and where there is a responsibility to identify material which may undermine the prosecution case or support the defence case. In my evidence to the committee I said the solution is to make available to the defence copies of all the forensic images that have been created by the prosecution. It is then open to a defence expert to use tools very similar or identical to those used by the prosecution to carry out the instructions of a defence lawyer. This surely satisfies the aims of disclosure in every practical respect.
There are protections against abuse of disclosed material, specifically sections 17 and 18 of the Criminal Procedure and Investigations Act 1996. There is a criminal offence involved and even if there were not there is still the possibility of contempt of court. (Yes, in the course of examining digital devices I do see information which the owners would regard as private and highly personal but which is also wholly irrelevant to the subject matter of charges. I don’t even share these with instructing lawyers).
Let us now look at the position of what happens in rape trials, an issue extensively canvassed by subsequent witnesses. The main protection is discussed in the CPS Manual: https://www.cps.gov.uk/legal-guidance/rape-and-sexual-offences-chapter-4-section-41-youth-justice-and-criminal-evidence. References is also made to Criminal Procedure Rule 22 (https://www.justice.gov.uk/courts/procedure-rules/criminal/docs/2015/crim-proc-rules-2015-part-22.pdf). (I am fully aware of and sympathetic with concerns that defence lawyers from time to time abuse rape victims in the witness box by asking aggressively about previous sexual history. But it seems to me that if the procedures laid down under s 41 Youth Justice and Criminal Evidence Act 1999 and CPR 22 are inadequate the remedy is to reform that part of the law and the linked judicial guidance rather than to take steps which would make digital evidence significantly less reliable. It may also be the case that inadequate funding for the police and CPS mean that the right applications are not made to the court in a timely fashion.
