Setting the record straight

The Court of Appeal's ruling in the so-called 'shaken baby' hearing of Henderson v R; Butler v R; Oyediran v R [2010] EWCA Crim 1269 has provided detailed guidance for future cases of infant deaths, both where medical evidence is involved and where expert evidence plays a key part in a trial.

The way in which the expert evidence is prepared and then utilised is 'of the utmost importance in achieving just resolution'. Expert evidence is needed to show the factual cause of death and opinions as to how those symptoms were produced; the ultimate aim where a defendant has pleaded not guilty is 'to prove that the individual defendant is lying in the account he gives, either at the time [of discovery] or at trial'. In all three cases, the accused had provided an explanation or suggestion for the injuries to the children, or given an account in which essentially nothing had happened and the cause of the symptoms was unknown.

If a verdict is sought entirely on the basis of expert evidence, whether of fact or opinion, it must be reached on 'a logically justifiable basis'. If a case does not proceed in such a fashion, any conviction is likely to be found to be unsafe (see Kai-Whitewind [2005] EWCA Crim 1092).

Preparing the way

Where a jury is to be presented with conflicting expert evidence, the evidence needs to be properly prepared for them and they need to be properly directed by the judge. The trial judge should 'have experience of the complex issues and understanding of the medical learning' although this may be difficult to achieve in criminal trials. The trial judge should conduct all significant pre-trial hearings in the case and engage in 'proper and robust' case management.

The real medical issues have to be identified pre-trial, not least to prevent the experts from going into too much detail '“ 'avoidable detail [has to] be avoided' for the benefit of the jury.

The judge should consider any previous judicial criticism of a proposed expert and address 'any tendency to travel beyond their expertise'. Although the judge may not reject such a witness, the party proposing to rely on that evidence 'may well [have] second thoughts as to the advisability' of doing so. Any previous reports by the expert which are relevant to the present case and previous criticism should be disclosed pre-trial; the judge may direct this under the Criminal Procedure Rules 2010, part 33. Non-disclosure 'will achieve no more than to expose the expert to cross-examination on those points at trial' (if discovered later). Non-disclosure by either side will only undermine the credibility of the expert's opinion and 'a defence team which advances an expert without [making such disclosure] is likely to damage its client's case'.

Admissibility of expert evidence

Identifying the precise issues in the case is also necessary to determine the admissibility of the proposed expert evidence. Moses LJ said this determination was 'as difficult as it is important'. The court followed the approach taken previously in Reed [2009] EWCA Crim 2698 and Harris [2006] 1 Cr App R 5, both based upon Bonython [1984] 38 SASR 45.

First, focus on the specific issue in the case '“ is it one on which the fact finders require expert assistance? If so, then look at the proposed witness '“ is this individual someone who, by their studies or experience, has sufficient knowledge of the relevant subject matter to make their opinion worth hearing?

Finally, is this field of knowledge sufficiently reliable to be adduced? Parties should be able to call evidence which is based on new techniques or new advances in science, where they are sufficiently well-established to be both relevant and reliable.

The court noted that the admissibility of expert evidence in criminal cases is currently under consideration by the Law Commission and observed that this is 'likely to lead to changes in the current [judicial] approach of laissez-faire'. However, although the Law Commission promised a final report for 2010, it has not yet been published.

The court commended the cautionary note sounded in 2004 by a working group chaired by Baroness Kennedy QC '“ doctors should not use the courts as a testing ground 'to fly their personal kites or push a theory from the far end of the medical spectrum' (see the Sudden Death in Infancy report from the Royal College of Pathologists and The Royal College of Paediatrics and Child Health).

One could regard this as a matter for self-policing by doctors and other experts, but the court said that a trial judge needs to apply a four-part checklist before ruling on admissibility, presumably at a pre-trial hearing:

1. Is the proposed expert still in practice?

2. To what extent is he an expert in the subject to which he testifies?

3. When did he last see a case in his own clinical practice?

4. To what extent is his view widely held?

The second and third points seem quite straightforward. However, the first and fourth points are significant developments to current practice. The court attached great importance to experts being in clinical practice and seeing cases '“ this continual experience 'gives them the opportunity to adjust previously held opinions' and alter their views accordingly.

Current clinical experience 'may provide a far more reliable source of evidence than that provided by those who have ceased to practice'.

The pre-trial hearing should direct that the parties' experts must meet and discuss the issues. This meeting should be held well before the trial date. All the significant experts should attend, but preferably not the parties' lawyers. A 'careful and detailed minute' should be produced, setting down the areas of agreement and disagreement, and signed by all participants. This accords with Crim PR 2010, rule 33.6(2); the court also highlighted rule 33.6(4) '“ if an expert fails to comply with such a direction, the party wishing to call that expert cannot do so without the court's permission.

Fresh evidence

At Keran Henderson's 2007 trial at Reading Crown Court, the prosecution called three medical witnesses as to the symptoms observed in the deceased, Maeve Sheppard, and a further eight experts whose function was to exclude so-called 'natural' causes of death as the explanation.

The defence had reports from experts before the trial but did not call them; they sought leave to call expert evidence as fresh evidence before the Court of Appeal.

Obviously this is provided for by the Criminal Appeal Act, section 23. In all three appeals, the court heard from experts, in some instances de bene esse. However, there should not be simple repetition of evidence already heard at trial, albeit perhaps given by different experts.

A tactical decision not to call defence experts at the trial should not advantage an appellant in terms of the ability to adduce 'fresh' evidence. 'Trial by jury' does not mean two bites of the cherry '“ trial by a jury at first instance and then by a panel of judges on appeal.

In such appeals, counsel needs to be expert in the relevant field of the unexplained death of, or injury to, a child. (This may be easier to achieve than the allocation of a trial judge who is an expert in the relevant field.) In particular, the court is reliant upon counsel to identify the issues for the court to concentrate upon as well as the evidence which determines the resolution of those issues.

Paperwork

Skeleton arguments were of considerable assistance to the court; here, different features of the medical evidence had been clearly identified, any medical propositions were explained and their sources identified. In such appeals, several different disciplines could be involved (for example, ophthalmology and neuropathology).

The use of separate files, distinguished by colour, to identify the different disciplines was helpful. Those files should contain the expert opinions and the factual evidence supporting those opinions, as well as any secondary literature which was relied upon. In Henderson, the appellant's QC had prepared a 'core literature file' similar to a literature review in a dissertation, showing the court what, where and how much published literature there was which could support the experts' opinions. This was important when weighing the support for each opinion.

A detailed case management hearing in Henderson had established timetables and directed preparation of the expert evidence. The experts met and identified the issues on which they agreed and disagreed. The approach taken in preparing the Henderson appeal was a model to be followed in the future.

Summing up

The summing up should be a 'logically justifiable conclusion' to the trial. This will be determined by the structure and quality of the judge's directions. Before closing speeches, judge and counsel should discuss the issues relating to the medical evidence. The judge should then be clear as to what the issues are and what is the evidence which relates to each issue. The summing up should proceed issue by issue and deal with the relevant opinions and written sources for each issue in turn. Any jury hearing such a summing up should be able to see the route that they need to take to reach a verdict. The judge should not simply reiterate the opinion evidence witness by witness as this will only confuse the jury.

Where there is a realistic possibility that the explanation for the injuries is that their true cause is currently unknown, the jury must be reminded of that and told that they cannot convict the accused 'unless the evidence leads them to exclude any realistic possibility of an unknown cause'. In appropriate cases, the judge may remind the jury that medical science develops and that courts 'must recognise the limits of medical science... in particular that there may be events, deaths or symptoms which are unexplained and unforeseen'.

The jury should be directed on how to resolve conflicting expert evidence. Such conflicts are not in themselves a reason to withdraw the case from the jury but 'juries should not be left to flounder in the formation of a general impression'. They should be given 'pointers to reliable evidence' by the judge. These may include, where appropriate:

a. Has the expert, in giving his evidence, assumed the role of an advocate, seeking to advance the cause of the party calling him?

b. Has he strayed outside of his area of expertise?

c. Has he identified a recognised, peer-reviewed, source to support his opinion?

d. Does he have current clinical experience and is it the equal of those witnesses whose opinion he contradicts?

None of these is conclusive but offering such pointers should allow the jury to adopt a 'rational process of analysis'.

Medical precedent

In any appeal, there may be relevant evidence which has remained undiscovered by the parties to the appeal or there may be subsequent developments in scientific knowledge. This means that the Court of Appeal cannot establish a binding precedent for a medical opinion '“ appeal courts depend upon the experts whose evidence is heard, at trial or appeal, and any legal decisions must recognise the primacy of that evidence.

The legal judgments which must be made are case-specific. A court is not a forum which is capable of resolving medical controversy; it can only make specific findings of fact which are dependent upon the particular evidence adduced and accepted in that hearing, itself dependent upon the legal framework dictated by the choice of which offence to charge. This should not be read as limited to medical issues but as a more general principle that should apply to any case turning upon contentious expert opinion evidence.