Stewart v Glaze

Accident Reconstruction Evidence

[2009] EWHC 704 (QB) 

The Facts

Mr Stewart sustained a serious brain injury when he, a pedestrian, was struck in the early hours of the morning by a motor vehicle driven by Mr Glaze. The evidence was that Mr Stewart was sitting at a bus stop with his friend. They had been out for the evening and Mr Stewart was drunk. His friend gave evidence that, inexplicably, Mr Stewart got up and ran into the road. Liability was tried as a preliminary issue.

The Issues

The issues were whether Mr Glaze was negligent in either failing to stop (and thus avoid the accident in full) or failing to slow down such that the injuries would have been less serious.

The Expert Evidence

There was expert Accident Reconstruction evidence for both parties.

They had both examined the forensic evidence, drawing conclusions about the speed of Mr Glaze’s vehicle; the point of impact; the probable path of Mr Stewart; and whether Mr Stewart was moving or stationary at the point of impact.

The most important part of their evidence (and the part that the Judge found most helpful) was a table setting out agreed figures, based upon the various factual scenarios open to the Judge, for what time Mr Stewart would have spent moving on the pavement and in the road prior to the accident. They had considered and agreed differing times for Mr Stewart running and walking during his manoeuvre and for whether he had run into the road at 90 degrees to the pavement or 45 degrees towards Mr Glaze’s vehicle. Accordingly, in each of these scenarios, they had been able to agree whether Mr Glaze would have been able to stop or not.

The Accident Reconstruction expert for Mr Stewart sought to given oral evidence that if Mr Glaze had slowed prior to impact (even if he had not avoided it) the injuries would have been less serious on the basis of a Government leaflet “Speed Kills”. The Expert for the Defendant disagreed, not least of all because the data was old and the leaflet had been withdrawn.

The point between the two experts was said to be “a matter for the Court, namely, in applying the standard of the reasonable driver, when should Mr Glaze have applied the brakes?”. The point was summarized in the joint report as:

“In…[the Defendant’s] opinion, if the pedestrian walked into the roadway, or ran in a moderate way then stopped, before the collision, then a timely and hard braking application by Mr Glaze would have enabled him to stop before the impact, if he started to react before Mr Stewart started to move. However, if Mr Glaze started to perceive a need to brake after Mr Stewart had started to move, but before he had entered into the roadway, and if Mr Stewart as running, then the collision would have been unavoidable by braking alone”.

There was no medical evidence upon the issue of whether or not the injuries would have been less severe had the impact been at a lower speed. The only medical evidence (which was agreed) attempted to define whether, by reason of the injuries, it was possible to say whether Mr Stewart had been moving or stationary at the time of impact. On the basis of the injuries, it was impossible to say.

The Decision

The Judge reiterated the test to be applied in such cases and the remit of Accident Reconstruction evidence.

Firstly, the test:

“I have to apply to Mr Glaze’s actions the standard of the reasonable driver. It is important to ensure that the Court does not unwittingly replace the test with the standard of the ideal driver. It is also important to ensure, particularly in a case with accident reconstruction experts, that the Court is not guided by what is sometimes referred to as ‘20-20’ hindsight”

Secondly, the remit of expert Accident Reconstruction evidence:

The Judge referred to the often-cited passage in Liddell v Middleton [1996] PIQR P36, per Stuart-Smith LJ:

“In such cases the function of the expert is to furnish the Judge with the necessary scientific criteria and assistance based upon his special skill and experience not possessed by ordinary laymen to enable the judge to interpret the factual evidence of the marks on the road, the damage or whatever it may be. What he is not entitled to do is to say in effect ‘I have considered the statements and/or the evidence of the eye-witnesses in this case and I conclude from the evidence that the defendant was going at a certain speed, or that he could have seen the plaintiff at a certain point’. These are facts for the trial judge to find based on the evidence that he accepts and such inferences that he draws from the primary facts found. Still less is an expert entitled to say that in his opinion the Defendant should have sounded his horn, seen the plaintiff 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. These are matters for the Court, on which the expert’s opinion is wholly irrelevant and therefore inadmissible… We do not have trial by expert in this country; we have trial by judge. In my judgment, the expert witnesses contributed nothing to the trial in this case except expense. For the reasons that I have indicated, their evidence was largely if not wholly irrelevant and inadmissible. Counsel on each side at the trial succumbed to the temptation of cross-examining them on their opinions thereby lengthening and complicating a simple case…In road traffic accidents it is the exception rather than the rule that expert witnesses are required.”

That said, the Judge observed that both experts had been able to provide some assistance in this case.

The Judge found that Mr Glaze was not negligent in failing to stop prior to the accident and thus avoid the collision in full.

The Judge did not criticize Mr Glaze for failing to react before Mr Stewart had started to move nor when he was moving towards the kerb and before entering the road. He did not criticize him for not seeing Mr Stewart before he had actually stepped onto the road as he accepted there were other matters for a driver to look out for as well as pedestrians at the bus stop. Accordingly, on the basis of the agreed expert evidence, (even taking into account margins of error), Mr Glaze did not have time to stop. Accordingly, Mr Stewart’s claim failed on the first issue.

As to whether the injuries would have been less serious had Mr Glaze slowed his vehicle prior to impact, the Judge found that there was no cogent evidence that might have assisted him reaching such a conclusion. He was not assisted by the generalizations given by the Claimant’s Accident Reconstruction expert on this point. Although he accepted that there was a possibility that the injuries might have been less severe, he found that there was nothing to indicate any probability either way. Medical evidence was required to enable a conclusion to be reached. This was said to be similar to a case where a Defendant was alleging failure to wear a seat-belt or cycle helmet leading to a more severe injury. In such cases, the evidential burden was on the Defendant but the point was the same. Medical evidence in support of the allegation in the particular case was required. A generality that a lower speed would cause a lesser injury might be correct but was not sufficient.


This case reiterates the importance of an Expert staying within his or her remit. The facts are the exclusive realm of the trial judge. However, importantly, it makes clear that an Expert taking the different factual scenarios and offering Expert assistance on the basis of each is not only within his or her realm but helpful to the trial judge and it is part of the role.

Finally, if you are asked as an Expert witness to comment out of your area of expertise, do not do it! By all means give reasons why you cannot and be prepared to discuss it with those instructing you but you only stand to discredit yourself if you do step outside your own area. In this case, the Experts did deal with the generality of lower speeds meaning lesser injuries. That is fine in so far as it goes but it was recognised that a medical expert would be required to talk about the specifics.

Search our registers

Contact Us