Experts Must Consider All the Evidence

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In the recent High Court case of Rowbottom v The Estate of Peter Howard, Deceased & Anor [2023] EWHC 931 (KB), HHL Sephton KC highlighted how important it is for experts to consider all the evidence in a case when providing their opinion — rather than simply referencing evidence in support of their opinion.

A second reason why I do not feel able to rely upon Mr Green is that he did not appear to me to understand the obligation of an expert fairly to deal with all the evidence and not simply to address the points that support his hypothesis. Mr Hunter’s criticism is fair that Mr Green was happy to emphasise the witness evidence that supported his theory whilst remaining silent about those witnesses whose evidence did not.”

Read our summary below for the salient points of this case.


The claimant, a pillion passenger on a motorcycle, sustained serious injuries when she was involved in a head-on collision between the motorcycle and a vehicle. The driver of the motorcycle was tragically killed in the accident.

The claimant sued both the driver of the vehicle and the estate of the motorcyclist.

HHL Sephton KC read and heard the evidence of several witnesses of fact. He also heard from three accident reconstruction experts who were instructed by the claimant, the estate of the motorcyclist (first defendant) and the driver of the vehicle (second defendant) respectively.

The expert witness of the second defendant gave evidence stating that the crash was caused by the first defendant driving on the wrong side of the road. The witnesses of fact were unable to provide evidence  to state exactly where the vehicles were situated at the moment of impact.

Therefore, the Judge turned to the expert evidence.

Expert Evidence

The Judge expressed criticism towards the expert witness of the second defendant, giving two main reasons. Firstly, the nature of his evidence, which he stated was ‘obviously incorrect’ and ‘palpably false’. Secondly, his conduct as an expert witness.

Addressing the second point, he stated that the expert was ignorant of his obligation to ‘fairly deal with all the evidence’ and had sought to cherry pick only parts of the evidence that supported his theory. For example, whilst his evidence relied upon the marks on the upright of the Recycling sign, he failed to draw the court’s attention to the fact that there were several other marks on the upright that were not consistent with his theory.

This meant that when his theory was discredited by the evidence in cross-examination, he proceeded to present an alternative theory. Unsurprisingly, this did not sit well with the Judge who questioned why this potential explanation had not been mentioned before. He, therefore, formed the opinion that it had been made up on the spot.

In contrast, the Judge was impressed by the other two experts. The claimant’s expert, he felt ‘carefully weighed all the evidence and had presented a persuasive account.’ The first defendant’s expert ‘carefully analysed the evidence and presented a fair…convincing account of the collision in his written and oral evidence. In giving his evidence, he was firm but not inflexible.’

In addition, the Judge stated that his conclusions about this case were largely informed by the evidence of the first defendant’s expert.


The Judge found that the motorcyclist was on the correct side of the road when the collision occurred, and that whilst he was slightly in excess of the speed limit, this did not indicate either breach of duty or causation. Therefore, the claimant’s claim against the first defendant was dismissed.

The claimant’s claim against the second defendant, however, succeeded. It is not known if and to what extent this judgment might have been different had the expert complied with his obligations. Nevertheless, this presents a persuasive case for experts to ensure that their opinion is based on a careful consideration of all the evidence supplied to them, and not just the points that support it.

Author: Meera Shah

Thisa rticle was first published on Friday 2 June 2023