Response to the Law Commission’s Consultation

Executive Summary

The Law Commission proposal to introduce a pre-trial assessment of the expert evidence put before juries in criminal trials is to be broadly welcomed. Expert evidence is unusual in that it is based heavily in opinion. Unlike the facts brought to the court by other witnesses, opinions do not lend themselves so readily to testing through adversarial challenge. An experienced expert witness convinced of the veracity of his (properly formed) opinion cannot be deflected easily by a non-expert advocate. Indeed, the court already sees expert evidence as being a special type of evidence, and we contend that it deserves special handling if it is to inform rather than mislead, particularly in criminal trials dominated by expert evidence.

Based on 356 contributions from expert witnesses, we feel that the Law Commission’s proposals – including the use of guidelines to assist judges in their determination of evidential reliability for scientific and for experienced-based expert evidence – are workable in practice. Indeed, most of our expert witness contributors think that with a little extra effort they could provide the required evidence of underpinning reliability and that the tests would be likely to expose expert evidence with an inherently unreliable provenance.

Crucially, though, our expert witness contributors recognise that weeding out expert evidence with an inherently unreliable provenance will not do enough to solve the problem of expert evidence that is itself unreliable going before criminal juries. But they do think that the introduction of pre-trial meetings of the judge, lawyers and expert witnesses (similar to Daubert hearings in the US jurisdiction) would be more likely to achieve this. Such meetings would be designed to explore the expert evidence and provide time for its importance in the context of the litigation to be subject to a period of quiet reflection – a necessity denied in the current system. The vast majority of our expert witness contributors think that this approach would be likely to identify unreliable or irrelevant expert evidence before it was put before a jury.

As currently drafted, the additional time it would take for expert witnesses to prepare the evidence necessary to pass the tests set by the proposals will have non-trivial cost implications. Unless the Legal Services Commission has sufficient funds to meet this extra cost, the proposals will fail in practice.

The Law Commission’s views on the generic accreditation of experts as expert witnesses have been overtaken by the work of the Forensic Science Regulator. Accreditation may seem to offer an enhanced level of confidence in expert evidence. However, the truth is that accreditation can never assure quality because quality comes from each individual’s ongoing rigorous and error-free implementation of proper procedures; a priori accreditation can give us merely some measure of past performance. The only meaningful accreditation of an expert witness is as an expert, and that has to be undertaken by the expert’s professional regulatory body.