Thomas, R. v

An expert’s qualitative assessment may be admissible without a statistical evaluation, provided it has a sufficient scientific foundation, is based on relevant expertise or experience, and its limitations are made clear to the jury. Concerns about the strength of an admissible expert opinion will ordinarily be addressed through cross-examination and jury assessment, rather than exclusion, unless its unreliability or lack of foundation makes admission unfair.

A full, accurate and balanced summary of competing expert evidence can be an adequate jury direction. A case should be left to the jury where the evidence permits a reasonable inference supporting the prosecution, even though an alternative forensic explanation is possible.

The appellant was convicted at Luton Crown Court of possessing a prohibited firearm and causing grievous bodily harm with intent. He had been acquitted of attempted murder and had pleaded guilty to dangerous driving.

The prosecution alleged that he possessed and fired a Baikal pistol during an altercation outside a nightclub, wounding the victim. Its case included DNA evidence from the pistol, gunshot-residue evidence, CCTV footage and circumstantial evidence. The experts agreed that the low-level DNA result permitted some interpretation but not statistical evaluation. They disagreed whether it merely failed to exclude the appellant as a contributor or positively supported his contribution.

With permission, the appellant appealed against conviction. He challenged the admission of the prosecution DNA expert’s opinion, the adequacy of the summing-up, and the refusal of a submission of no case to answer on the grievous-bodily-harm count.

1. Appeal dismissed. The trial judge was entitled to refuse to exclude the prosecution expert’s opinion under section 78 of the Police and Criminal Evidence Act 1984. The expert was qualified, the DNA result was agreed to be capable of some interpretation, and her opinion was not so unreliable or unsupported as to be inadmissible or unfair to admit.

2. The court accepted the principle in R v Atkins [2009] EWCA Crim 1876 that an experienced expert may give an assessment despite the absence of statistical evaluation. The assessment must be approached cautiously and its subjective nature made clear to the jury. The prosecution expert’s unquantified opinion that the result provided support was unsatisfactory, and her reliance on unexplained simulation experiments was a concern. Nevertheless, she was entitled to rely also on her forensic experience. The proper course was to admit the evidence, expose its limitations in cross-examination, and leave its weight to the jury.

3. The court applied R v Weller [2010] EWCA Crim 1085: an expert may rely on unpublished material, experience and experiments. Here, the simulation experiments alone supplied a very thin basis for the opinion, but the expert’s own experience supplied a permissible additional foundation. Cross-examination had in any event reduced the practical significance of the disagreement between the experts to almost nothing. Admission of the opinion therefore could not have affected the safety of the convictions.

4. The summing-up was adequate. A correct general direction on expert evidence, coupled with a detailed, accurate and balanced account of both experts’ evidence and the prosecution expert’s concessions, was sufficient. The judge was not required to give further directions on how the jury should choose between their opinions.

5. The judge rightly left the attempted-murder and grievous-bodily-harm counts to the jury. Although the forensic evidence allowed the possibility that the victim’s bullet came from another firearm, the alternative depended on an unverified third-gun theory. Taken with the evidence linking the appellant to the Baikal pistol and placing him close to the victim, the evidence permitted a reasonable jury to find that he fired the shot.

• Court of Appeal (Criminal Division). The appeal against conviction was dismissed.
• Crown Court at Luton. Following a jury trial before His Honour Judge Bright QC, the appellant was convicted of possession of a prohibited firearm and causing grievous bodily harm with intent. He was acquitted of attempted murder.