UK: Determining Causation When The Competing Explanations As To How An Event Occurred Are All Uncommon, But Not Improbable

Ide v ATB Sales Ltd: Lexus Financial Services v Russell [2008] EWCA Civ 424

The Popi M principle: Where there are several explanations of the cause of loss, all of which are highly improbable, then the judge should not select the least improbable cause, but should decide the case on the basis that the claimant has not proved his loss.

The facts: In the Ide appeal, Mr Ide fell off a mountain bike imported by ATB and was seriously injured. After the fall, the left handlebar was found to have fractured. Mr Ide's expert contended that the left handlebar had been defective and caused Mr Ide to lose control and fall. ATB's expert contended that Mr Ide had lost control, fallen off, and the handlebar had been damaged in the fall. The judge found for Mr Ide.

In the Lexus appeal, Mrs R's car had been damaged by a fire in her garage. L had demanded the sum due from Mrs R under a hire purchase agreement. Mrs R refused to pay on the basis that a defect in the car had caused the fire. There were three possible causes of the fire: arson, a defect in the wiring in the garage and a defect in the electrics of the car. The judge found for Mrs R.

The appeals: ATB and L both appealed, arguing that the trial judges had adopted an approach to causation which was impermissible under the Popi M principle. Having dismissed the other explanations for the loss, the judges were not entitled to conclude on the balance of probabilities that there was a defect in the handlebar which caused Mr Ide to fall, or that Mrs R had shown that the fire was caused by a defect in the car's wiring.

The decisions: Neither case was a Popi M case. Although the explanations put forward in both cases were uncommon, they were not improbable.

In Ide, there were only two competing explanations; a defect in the handlebar or a fracture caused when Mr Ide fell off the bike. Neither cause was improbable. Once the least likely explanation had been eliminated, all the evidence pointed to a defect in the handlebar. The judge was entitled to conclude on the evidence that the defect was the probable cause of the loss of control of the bike and the fall.

In the Lexus appeal, once arson had been eliminated, the judge was left with two possible causes - the wiring in the garage and the electrics in the car. Both were uncommon but not improbable. It was therefore necessary to analyse as between the two which was the stronger probability. The judge was entitled to conclude on the evidence that the probable cause of the fire was a defect in the electrics of the car.

Comment: This case shows that unlikely but not impossible explanations do not fall foul of the Popi M principle. As a matter of common sense it seems highly unlikely that a mountain bike's handlebar would sheer off in normal use, or a car spontaneously catch fire when it had been parked in a garage for several hours, but as neither event was impossible, the judges were entitled to conclude that these explanations were the probable cause of the losses.

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