On rare occasions, there may be a risk that this will lead to the conviction of the innocent. And the lack of an unchallengeable record of interviews in which witnesses give statements to police poses the courts with a potentially much more serious problem. It is frequently a direct cause of the acquittal of the guilty.
When private eyewitnesses give evidence for the Crown, they almost invariably do so without having in front of them their original statements. These may have been signed months earlier and, although witnesses are usually given their statements to read outside the courtroom before they give evidence, differences often emerge which may undermine their credibility. Inconsistency is traditionally regarded as a useful indication of unreliability. But its value is often diminished by flaws in the existing system of recording witness statements. These are still almost always taken down in writing by officers involved to some extent in the investigation, and the content of a statement is likely to be influenced by the way in which the interviewer receives and formulates the narrative.
Often, a statement owes as much to the officer's controlling hand as to the witness's memory. It invariably excludes the questions, which may be leading and suggestive, and, with the best will in the world, the way in which the story is committed to paper cannot help but reflect the officer's subjective view of the facts. At the time of telling the police their story, witnesses may be exhausted, depressed, disoriented, unwell or preoccupied. Many witnesses are insensitive to the nuances of language. So, when the officer has taken down the statement and hands it to the witness to check and sign, crucial omissions, errors or distortions can easily be overlooked. On the other hand, the witness may simply be too tired or too timid to voice objections.
The result may be a document which substantially, if not fundamentally, diverges from what the witness intended to state. Of course, discrepancies may genuine, truly showing up the witness as unreliable or even dishonest. But defending barristers have long perfected the art of exploiting such inadequacies in order to cast "blame" on a witness for ostensible inconsistencies.
When a witness answering the prosecuting barrister's questions departs in some significant respect from an earlier statement to the police, the defending barrister in cross-examination will embark on a series of standardised entrapping questions designed to seal up escape routes. Finally, the trap is sprung, and on being confronted with the inconsistency, a witness will not uncommonly claim either that the officer put down something down that was not said, or that he or she left out something that was. If called to resolve the conflict, the attesting officer will rarely admit to inattention or error. So the witness is made to look unreliable or dishonest - not the officer, whose mode of interviewing and transcription may have been seriously at fault. At the very least, the conflict will remain unresolved, and the doubt will often be applied in favour of the undeserving accused.
Using an expurgated or inaccurate version of what a witness in fact told the police in private in order to pick holes in the evidence in court is harly conducive to getting at the truth. With our practices at the criminal bar stretching back some 25 years - mainly defending - we can say that this is probably the single most significant cause of wrongful acquittals. Not only do the Bar and the judges know it, but many influential police officers now publicly acknowledge the dangers. These include David Phillips, chief constable of Kent and secretary of the crime committee of the Association of Chief Police Officers. Research in the field conducted by Max McLean, a West Yorkshire detective chief inspector with an academic background, has demonstrated the validity of our claims.
The obvious solution is to audio-tape interviews in appropriate cases, including first reports of crime. (Video-recording would be even better.) Home Office guidance issued in 1992, and currently being re-evaluated, is confined to the brief suggestion that in "more serious cases, such as a fatal road accident or a serious assault", it may be "beneficial" to support note-taking by tape-recording the interview. No one would sensibly suggest that all witness interviews should be tape-recorded, since so many are obviously non-contentious. But clearly defined criteria are needed to determine which interviews should be tape-recorded, and in case of doubt the police should err on the side of caution. The tape would normally be available to the defence, except in rare instances where it meant the disclosure of confidential information.
We also believe that the entirely legitimate process by which officers pool recollections when writing up their notebooks needs to be tape-recorded. At present, defence barristers are frequently able to score valuable points by ridiculing police claims under cross-examination that several officers shared exactly the same memory of a given incident. We can remember countless acquittals where officers over-egged the pudding. Tape-recording would force the police to be more honest, and would make them more credible.
The Home Secretary, Michael Howard, and Jack Straw, his Labour opposite number, have been busy flexing their muscles on crime. It is an old truism that certainty of conviction is a more effective deterrent than severity of punishment. In improving the conviction rate, tape-recording witness interviews will do as much to reduce crime as ratcheting up sentences or importing prison hulks from America. The parties should use the election to promise compulsory tape-recording in appropriate cases.
There is another reason why tape-recording statements is more vital than ever. Statements to police are now admissible in substitution for the absent source of the evidence at trial in many circumstances. With the abolition - soon to come into force - of the right of defendants to demand that at committal proceedings prosecution witnesses give evidence "live" and in the presence of the defence, some statements, prepared as always by police behind closed doors, may end up being read at the trial without the defence having had any opportunity to test their reliability through cross-examination. If courts are going to make increasing use of such statements, the least we can ask is that we have an exact record of what the witness said, not what some police officer wrote down on the witness's behalf.
David Wolchover and Anthony Heaton-Armstrong are barristers who have made an extensive study of the issues they raise here.