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J S Publications’ initial response to the Law Commission’s Consultation Paper
The following is our initial response to the Consultation Paper. After reading this, you can:
We believe that the Law Commission's proposal to introduce a Daubert-style pre-trial assessment of the expert evidence in criminal trials is to be welcomed. Indeed, we have long called for just such a move because we see that problems with the court’s use of expert evidence have often arisen because that evidence has not come under close scrutiny until the trial.
Expert evidence is a special type of evidence
Expert evidence is unusual in that it is heavily based in opinion. 'Normal' witnesses testify as to fact, and the adversarial trial process is well suited to testing each witness for the honesty of their evidence. We do not think the same applies to the opinions that are the foundation of expert evidence.
Some expert evidence is mostly factual, but it requires expertise to acquire the facts. This class of expert evidence includes blood alcohol analyses and the calculation of slip coefficients.
Other expert evidence is based on experience. This class of expertise includes an experienced retailer giving evidence on what is custom and practice in his trade.
If analytical procedures are correctly followed and all the evidence is put before the court (even those tests which seem to the expert to give irrelevant or erroneous results), there is little scope for these classes of expert evidence to mislead. However, much expert evidence is based to some degree on opinion. This is where problems can arise.
Much supposedly scientific evidence is, in truth, the opinion of a scientist based on his training, his experience and (possibly) some test results. For example, the expert evidence that a head injury was non-accidental is based purely on the presence of three intra-cranial injuries (acute encephalopathy, bleeding around the brain and retinal bleeding). It is fact whether or not the three injuries are present, but it is an opinion that this triad of injuries means non-accidental injury. Or take ear-print (or fingerprint) evidence. Whilst deterministic measurements are taken to characterise a print, it falls to the opinion of the examiner as to whether the print matches that of a suspect.
This opinion class of expert evidence is recognised by the courts as being a special type of evidence, and we believe it demands special treatment if it is to inform rather than mislead the court. There are cogent arguments against allowing the traditional adversarial approach to hold sway, not least of which is the apparent unwillingness of juries to accept the uncertainty introduced by differing opinions. More troubling to us is the willingness of judges to accept majority verdicts in criminal cases dominated by conflicting expert evidence, e.g. the Keran Henderson case. Isn’t a 10-2 majority verdict the very definition of reasonable doubt?
Adversarial challenge of expert evidence
What ought to happen is for the opinion evidence itself to be probed and for its basis in science or experience to be tested and challenged. But how often does the barrister turn from this difficult task to use familiar techniques to simply undermine the credibility of the expert?
Now, experts ought to be up to this challenge. Attacking the credibility of the individual is acceptable if it is focused on determining whether he is truly expert and capable of giving unbiased evidence. But when it is used as a proxy to the more challenging task of testing the science, does it serve the interests of justice? We think not.
We argue that the trial is not the sort of environment that is conducive to the careful analysis of complex evidence drawn from a body of knowledge that is, by definition, alien to the jury, judge and lawyers. Such analysis takes time and often requires the opportunity for quiet and considered reflection. This simply cannot be done at trial.
Of course, for many cases the expert evidence will not be hugely complicated, or it will not be central to the determination of the issues in the case. Leaving the examination of this evidence until the trial may be appropriate, but when the expert evidence is complex and/or the trial depends principally on that evidence, experience has shown that the current system does not work that well.
By introducing an early assessment of the reliability of the underlying body of knowledge from which the expert evidence is drawn, the Law Commission proposals go some way to addressing the problems that arise from delayed scrutiny of the expert evidence. But are they workable? Do they go far enough? Would they have dealt with the cases put forward by the Law Commission as justification for the changes it proposes?
Are they workable in practice?
In order to work, these proposals would require all experts to be able to demonstrate that their opinions are drawn from a sufficiently reliable body of knowledge. Is this practical? Would it bar some categories of evidence that find such objective validation of their underpinning methodologies difficult to achieve?
Since it is only the body of knowledge from which evidence is drawn that is being tested, would the courts over time simply come to use predominantly judicial notice (i.e. relying on the findings of earlier courts that a particular type of expert evidence is sufficiently reliable) rather than bothering to enquire into the evidence on a case by case basis?
Requiring experts to prepare the additional justification material will involve additional costs. Will the LSC be in a position to meet these costs, or would they fall on the expert?
Some will ask whether judges are capable of assessing the methodological underpinnings of scientific evidence. While it must be helpful to educate judges in the proper assessment of scientific methodologies, placing the onus on those who seek to adduce a piece of expert evidence to demonstrate its suitability seems to make this training less critical than if an inquisitorial system was being proposed. What we would need is judges who are critical consumers of science, not judges who are scientists.
Testing the proposals against past cases
It is natural to look at the four cases the Law Commission cites to see if their proposals would have prevented the problems the Commission identified.
Dallagher
Despite the novelty of ear print evidence as used in Dallagher, the Court of Appeal has been adamant that such evidence can be adduced, but that the court should pay due notice to the inherent unreliability of such novel techniques. It seems to us that ear print evidence is little different from fingerprint evidence, albeit that ears are more ‘squashy’ and so the distances between key features will not be static but alter with changes in pressure.
If the Law Commission’s proposals are not to introduce a Frye-type test, it seems to us that ear print evidence will continue to be admissible.
Clark
The Law Commission focuses on the second Court of Appeal case to call into question the statistical evidence given in court by Meadow. The second appeal heard no evidence on statistics and little argument, but Kay LJ still felt able to offer the following dicta:
'Thus it seems likely that if this matter had been fully argued before us we would, in all probability, have considered that the statistical evidence provided a quite distinct basis upon which the appeal had to be allowed.'
In our view this is a most unfortunate dicta. In contrast, the first Court of Appeal did hear evidence on the statistical evidence and it found that in the context of the trial it had 'minimal significance'.
Let us not forget that Meadow was quoting published data. Indeed, Professor Berry, one of the editors of the book being cited, also gave evidence and pointed out the implicit danger of simply multiplying the probabilities. Furthermore, limited time was spent on these statistics because they related to SIDS, and no-one was maintaining that the deaths were the result of SIDS.
However, despite misgivings about the way the Law Commission makes it case, we do agree that if the court had been able to explore this evidence ahead of the trial, it is very likely that it would have been excluded as irrelevant. It related to SIDS, and no-one was maintaining that the deaths were the result of SIDS.
Cannings
The Cannings case is more persuasive because the initial convictions where based almost entirely on conflicting opinion evidence and, as noted by the Court of Appeal, in such cases it is unwise to proceed. But at what point under the current rules can the court decide to stop proceedings? If the proposed evidence of the experts had met the test of methodological reliability, the trial would have proceeded anyway and these proposals would not have prevented it.
Unless the court can look at the particular evidence in a case, and not just the reliability of the underpinning methodologies, the Cannings-type case will not be prevented. What is needed to prevent another Cannings is a power for the judge to prevent a trial that 'depends exclusively, or almost exclusively, on a serious disagreements between distinguished and reputable experts' being put to the jury. That could happen after the evidence has been put to the jury, or we think - perhaps better - after a pre-trial hearing of the expert evidence.
Harris and others
The case of Harris and others is very persuasive because the source of the problem was the poor quality of the database underpinning the triad of intracranial injuries. These proposals would have ensured that this flaw was discovered before the evidence was placed before the jury.
So, in respect of Dallagher, Clark and Cannings, we do not believe that the Law Commission’s proposals would have made a difference. In Harris and others, it would have made a difference. However, this does not mean we reject the proposals. We just don't think justifying them on these grounds was necessary or effective.
Do they go far enough? The case for Daubert hearings
The Law Commission proposes that the party wishing to adduce expert evidence should be prepared to demonstrate the reliability of the body of knowledge from which it is drawn. Critically, that is not the same as determining if the proposed evidence is in fact correct. It would remain for the trial process to determine what weight to apply to any expert evidence adduced. But the pre-trial assessment would aim to remove at an early stage any evidence found to be based on a body of knowledge that is unable to sustain a claim to be able to generate reliable evidence.
So the proposed changes will result in the methodological underpinning being tested ahead of the trial, not the actual expert evidence. Does this go far enough?
We believe that any move to earlier assessment of expert evidence is a good thing. On that basis we support the Law Commission’s proposals. But we would go further. When the complexity of the expert evidence in a trial warrants it, we believe that the court should have the ability to call a pre-trial hearing at which the judge, the lawyers and the expert witnesses would come together to critically appraise the expert evidence. The purpose of this hearing, which would be far less formal than the trail, would be to allow all concerned to hear all the expert evidence in context. The participants at the meeting would be encouraged to probe and explore the ramifications of the evidence to be adduced. Crucially, the participants would automatically get the time for necessary quiet reflection to really appreciate the import of the evidence as they wait for the trial proper to arrive.
Such a process might permit a judge to make a ruling to exclude some of the evidence as being irrelevant or inadmissible for other reasons, e.g. the evidence is unreliable even though it is drawn from a body of knowledge that is capable of delivering reliable evidence. It would also act to prevent the barristers playing their adversarial games with opinions.
In general, any move to put expert evidence under closer pre-trial scrutiny is welcomed. But a Daubert-style assessment of expert evidence is not a panacea. The system must also:
- ensure juries become more ready to accept the doubt that is implicit in expert opinion evidence
- give the power to a trial judge to follow the Court of Appeal decision in Cannings and be able to stop a trial that has become overwhelmingly dominated by serious disagreements between eminent experts
- not permit majority verdicts in cases dominated by expert evidence.
Accreditation
The Law Commission refers to the possible use of accreditation as a way of improving the quality of expert evidence. We utterly reject this idea.
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 every individual’s ongoing rigorous and error-free implementation of proper procedures; a priori accreditation can only give us some measure of past performance.
The Forensic Science Regulator has moved the focus away from accrediting individuals as expert witnesses. The CRFP has closed its doors. The Office for Criminal Justice Reform explored the possibility of changes to the law to introduce compulsory registration of forensic practitioners and expert witnesses. They decided against seeking changes to the law to introduce mandatory registration, preferring to leave registration as a matter of policy rather than law. Their reasons for this include the complexity and cost required to achieve a large inclusive list of experts.
The Better Regulation Executive's principles teach us that the very best regulation of the quality of expert evidence would offer transparency, accountability, proportionality and consistency, and would be targeted according to need. We already have such a system in place – it is the detailed scrutiny that can be brought to bear by the lawyers, the judge and the other expert witnesses upon the evidence adduced in a case within the context of that case.
Of course, even with this optimal system in place, problems with expert evidence in the criminal justice system have arisen in the past. But these have usually stemmed from a systemic failure of the court properly to handle conflicting or novel scientific evidence, due in part to inadequate court procedures. We believe that the Law Commission's proposals are a positive step towards tackling these systemic weaknesses, but hope that more can be done.
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