Armstrong & Anor v First York

Expert evidence, including the evidence of a single joint expert, does not determine liability. The trial judge must evaluate it alongside the factual and other evidence, apply the burden of proof and decide where the probabilities lie.

Where credible factual evidence conflicts with expert opinion, the judge should seek to reconcile the evidence and consider possible explanations for the conflict. The judge may reject the expert opinion on proper evidential grounds without identifying a technical error in it. Adequate reasons must explain the resulting choice.

The defendant appealed from a decision of His Honour Judge Stewart QC in Liverpool County Court finding it liable for soft-tissue injuries allegedly sustained when its bus delivered a shallow, glancing blow to the claimants’ stationary car.

The claimants gave evidence that the collision jolted them and caused injury. Medical evidence and contemporaneous records afforded some support. A single joint forensic engineer concluded that the impact could not have displaced the vehicle’s occupants. The alternative defence alleged fraud.

The judge accepted the claimants as honest witnesses and inferred that the engineering opinion contained an unidentified error. The central issue was whether he could reject that opinion without identifying a technical flaw in it.

1. Appeal dismissed. Brooke LJ, with whom Arden and Longmore LJJ agreed, held that the trial judge had directed himself correctly and was entitled to find for the claimants on the evidence as a whole.

2. There is no principle that expert evidence in an unusual or developing field must determine liability. The trier of fact must apply the burden of proof and assess all the factual and opinion evidence. As stated in Liddell v Middleton [1996] PIQR P36, trial is by judge, not by expert.

3. Where credible factual evidence conflicts with expert opinion, the judge should attempt to reconcile the evidence. If that is impossible, the judge should consider possible explanations for the conflict or error and make a considered choice. The approach in Cooper Payen Ltd v Southampton Container Terminal Ltd [2003] EWCA Civ 1223 did not compel acceptance of the expert in this case. Unlike that authority, the claimants supplied substantial factual evidence which the judge was entitled to accept.

4. The judge had proper grounds for rejecting the engineering conclusion. These included his careful assessment of the claimants’ credibility, their consistent accounts, the medical evidence and the contemporaneous record of their hospital attendance. Since accepting the expert’s conclusion would have required a finding that the claims were fraudulent, the judge was entitled to treat his conviction on proper evidence that the claimants were honest as a reason for rejecting the contrary opinion.

5. Arden LJ added that a judge need not identify why expert evidence is technically wrong before rejecting it. The judge must nevertheless have grounds for rejection and give reasons satisfying the standard described in English v Emery Reimbold & Strick Ltd [2002] EWCA Civ 605. The reasons given here were clear and sufficient.

• Court of Appeal (Civil Division): The defendant’s appeal was dismissed by [2005] EWCA Civ 277.
• Liverpool County Court: His Honour Judge Stewart QC found for the claimants on liability on 11 March 2004 and granted permission to appeal. No citation is stated.