The role of expert reconstruction evidence

The trial of an action arising out of a ?road traffic accident often involves a lengthy and detailed analysis of the circumstances surrounding an accident which itself occurred in the blink of an eye. Many hours of court time can be taken up carrying out a painstaking dissection of the brief moments relevant to the accident in question. As Lord Justice Laws observed, this can often lapse into a test of ‘fine considerations elicited in the leisure of the court room, perhaps with the liberal use of hindsight’, and, as such, becomes artificial (see Ahanonu v South East London and Kent Bus Company Ltd [2008] EWCA Civ 274). 

Introduce expert evidence on the issue of liability and the process can become even more divorced from reality. In high-value cases, the parties often seem unable to resist the temptation to introduce expert evidence, even where the circumstances do not suggest that this will ?be of any use to the court. It is common for trial judges to express frustration with the use of reconstruction experts or the manner in which such evidence is presented. There is, however, a limited role for expert reconstruction evidence. 

Determination of facts

The most important evidence in road traffic accident cases is the primary evidence from the participants and eyewitnesses, who can describe what actually happened. In most cases, no expert is needed because the lay evidence, together with a police accident report, is sufficient to determine the critical facts, such as the speed of the vehicles, road conditions, positions of pedestrians, and so forth. Expert evidence can be a useful tool with which to test the lay evidence, but even then it must be seen as subordinate to the primary lay evidence. 

Where there is little primary evidence to describe what actually occurred, then reconstruction evidence can be particularly useful. In Stewart v Glaze [2009] EWHC 704 (QB) Mr Justice Coulson observed that ‘the expert evidence comprises a useful way in which the factual evidence, and the inferences to be ?drawn from it, can be tested. It is, however, very important to ensure that the expert evidence is not elevated into a fixed framework or formula, against which the [d]efendant’s actions are then to be rigidly judged with a mathematical precision.’ 

The expert must be careful not to usurp the function of the trial judge but to keep to matters within their expertise. As Mrs Justice Cox explained in Sinclair v Joyner [2015] EWHC 1800 (QB), ‘the reconstruction expert’s role is to provide the judge with the necessary scientific criteria and assistance based upon his or her specific skills and experience, which the lay judge will not usually possess, to enable the judge to interpret the factual evidence. It is not… to discover the facts and… to give an opinion as to what happened.’ 

The determination of what happened solely lies within the domain of the trial judge and no expert should present evidence in such as way as to suggest they are determining this issue. ?‘Still less is the expert entitled to say that, in his opinion, the [d]efendant should have sounded his horn, seen the [claimant] before he did, or taken avoiding action and that in taking some action or failing to take some other action a party was guilty of negligence’ (see the judgment of Lord Justice Stuart-Smith in Liddell v Middleton [1996] PIQR P 36). 

Interpreting evidence

The reconstruction expert can assist where there is evidence, such as tyre marks, debris on the road, or damage to vehicles, from which calculations can be made and opinions drawn as to the likely speed of vehicles and the time over which observations could have been made, for example as to the presence of a pedestrian in the road. 

The length of and nature of a tyre mark would tell a lay judge very little but an expert could >> >>  assist in the interpretation of such evidence. Where a pedestrian has been killed, the position of the corpse and the final position of the vehicle can be used to calculate the speed of the vehicle and the position of the pedestrian at the point ?of the collision. These are obviously matters of scientific determination and clearly fall within ?the domain of the expert. 

In some cases, the expert not only usurps the trial judge’s role in determining the facts but becomes a zealous advocate for one side. ?Lawyers should resist the temptation to introduce superficially supportive expert evidence when really the expert is simply exhibiting bias. 

Even the most experienced of experts can give the impression of having become advocates for ?a particular cause. In Horner v Norman (Lawtel 20/12/2013), the claimant had purchased two bottles of vodka from a petrol station and was struck by the defendant’s vehicle as he was running across a road. The trial judge made these observations: ‘[The claimant’s expert] showed a willingness to become an advocate of the claimant’s case. He advanced opinions which were not answers to questions asked of him. ?His assertion in his report that vodka was not available for sale in the petrol station shop was as unfortunate (it was wrong) as it was surprising in an accident reconstruction report. When dealing with the topic in which he had no expertise, the running speed of a man, he was happy to factor ?in the carrying of a bag with bottles in it. ?His reconstruction of the post-accident position of the defendant’s vehicle was as fanciful as it was self-serving.’

In Chelsea Armstrong v Richardson [2014] EWHC 3306 (QB), however, the expert evidence was pivotal to the determination of liability. ?Three girls ran across a Tyneside road on a dark December night. The third girl was struck by the defendant’s motorcar, which was being driven at about 30 miles per hour (mph) in a 60mph zone. ?The claimant’s case was built upon the premise that having seen the first of the girls running across the road, the perception-reaction time (PRT) was such that the defendant ought to have been able to avoid the collision with the claimant. 

The trial judge found the ‘hot-tubbing’ of ?the two road traffic accident reconstruction experts to have been particularly successful. ?The experts agreed a calculation of the PRT at 30mph of 1.5 seconds, and this drove the judge ?to the conclusion that the defendant had indeed been negligent. In support of this conclusion, the trial judge cross-checked with primary evidence from the defendant as to where the first girl was when he first observed her. This was consistent with the experts’ agreed calculation of the PRT, and thus the conclusion of negligence was sound. 

Questions for the trial judge

The decision of whether expert evidence can be adduced at all often rests with a district judge or master at an interlocutory stage rather than the trial judge. In Team Tex SAS and others v Wang (Lawtel 20/05/2015), Mr Wang installed a car seat for his younger son. He thought he had installed the seat in accordance with the manufacturer’s instructions. Tragically, he drove on the wrong side of the road, causing an accident as a result of which his younger son suffered severe brain damage. 

The claim brought against Wang on behalf ?of the younger son was settled for £2.3m plus periodical payments. Contribution proceedings were brought, including a claim against the manufacturer of the car seat, alleging the instructions for installation were inadequate and therefore defective, giving rise to a cause of action pursuant to the Consumer Protection Act 1987. ?At an application to adduce evidence from an ergonomist, the master granted permission on the grounds that the interpretation of instructions was ‘not a question of textual clarity, but of practical adequacy and practical adequacy and related human processing are a matter for an ergonomist’. 

Pausing there, it does seem strange that the issue of whether instructions are adequate so as to allow a layperson to follow them should require the input of an expert. Judge Seymour QC allowed an appeal and refused permission for expert evidence, ruling: ‘[I]t is quite obvious to ?me in the circumstances of the present case that there is no sensible contribution which an expert in any discipline can make to the very simple question which the trial judge is going to have ?to resolve. That simple question is whether a person of reasonable intelligence who is tolerably familiar with the use of the English language could follow the instructions and warnings which were provided with the car seat in the present instance… I think we can safely suppose that ?the trial judge is of reasonable intelligence ?and adequately familiar with the provisions ?of the English language in order to reach a conclusion on that point.’

In order to keep expert evidence in its proper place and to restrict it to that which is reasonably required to determine the issues in a case, ?I suggest that, where possible, it would be better if decisions as to the use of expert evidence were taken by trial judges.

Roger Cooper is a barrister practising from Park Lane Plowden @ParklanePlowden www.parklaneplowden.co.uk