R v Benjamin Norman

The former rule preventing experts from expressing an opinion on the ultimate issue is no longer a rule of law. An expert may address that issue where the opinion is helpful and falls within the expert’s expertise. The expert must not compare competing explanations requiring expertise in different disciplines, or speculate beyond the evidence. The jury remains responsible for resolving disputed facts and weighing competing causes. It is not bound by expert opinion. Here, no expert could properly assess the relative likelihood of cannabis impairment and epilepsy as causes of the collision. The agreement not to seek such opinions was appropriate, and the conviction was safe.

Following a trial in the Crown Court at Luton, the appellant was convicted of causing death by careless driving while over the specified drug limit, contrary to section 3A(1)(ba) of the Road Traffic Act 1988. He was acquitted of causing death by dangerous driving and was sentenced to nine years’ imprisonment. An earlier appeal against sentence was dismissed: [2022] EWCA Crim 1738.

The appellant relied on an insanity defence, asserting that an epileptic seizure caused the collision. The prosecution relied on cannabis-induced drowsiness. Experts addressed the effects of cannabis and epilepsy, but counsel agreed that they would not be asked which cause was more likely. The central issue was whether the trial judge should have permitted expert evidence on that comparative question and whether the appellant consequently received a fair trial.

1. Appeal dismissed. The former rule excluding expert opinion on the ultimate issue is no longer a rule of law. The court adopted the approach in R v Stockwell (1993) 97 Cr App R 260: an expert may give an opinion on the ultimate issue, but the judge must make clear that the jury is not bound by it and remains responsible for deciding the issue.
2. That principle is subject to the limits of the expert’s discipline. An expert may not compare the relative likelihood of cannabis impairment and epilepsy where doing so requires expertise in both fields. An opinion unsupported by an appropriate evidential basis would be speculation and would fall outside the expert’s proper area of expertise.
3. The court explained the significance of R v Constantini [2005] EWCA Crim 821. Expert medical evidence about the cause of an accident may legitimately bear on the ultimate issue, but the jury must determine the underlying facts and decide how competing explanations are to be weighted. The jury is not required to accept the experts’ view.
4. In this case, the cannabis expert had no proper basis for comparing cannabis with epilepsy and expressly considered that question outside her expertise. The epilepsy experts had no demonstrated expertise in cannabis-related driving impairment, the duration of its effects, or the significance of the blood level. Their comparative opinions were unexplained or heavily qualified. Whether the appellant had smoked cannabis on the morning of the collision, and whether he had previously fallen asleep while driving after smoking, were factual matters for the jury.
5. The trial judge had not been asked to rule on the proposed evidence, so there was no criticism of her conduct of the trial. Counsel’s agreement was reasonable and appropriate. The experts would not have assisted the jury by speculating on the comparative causes. There was no unfairness, and the jury was entitled to conclude that the appellant had not proved on the balance of probabilities that an epileptic seizure caused the collision.

• Court of Appeal (Criminal Division): The appeal against conviction was dismissed on 1 September 2023. An earlier appeal against sentence had also been dismissed: [2022] EWCA Crim 1738.
• Crown Court at Luton: The appellant was convicted of causing death by careless driving while over the specified drug limit, acquitted of causing death by dangerous driving, and sentenced to nine years’ imprisonment.