Ide v ATB Sales Ltd & Anor

When several possible causes of damage are advanced, the court may compare their relative probabilities and infer that one was the probable cause. This approach is permissible where the identified causes exhaust the realistic possibilities and the selected cause is itself plausible.

The court must not select the least improbable cause from a series of inherently improbable explanations. If the evidence remains unsatisfactory, the claimant has failed to discharge the burden of proof.

In a product liability claim under the Consumer Protection Act 1987, the claimant must establish that a defect caused the damage. The claimant need not establish the precise mechanism by which the defect arose.

Two appeals were heard together because each concerned proof of causation where alternative causal mechanisms had been advanced.

In the first appeal, a cyclist suffered serious injuries after his mountain bike's handlebar fractured. Gray J held in [2007] EWHC 1667 (QB) that the handlebar was defective and that the defect caused the accident. The importer appealed on the limited basis that the primary findings did not permit that causal inference.

In the second appeal, a fire destroyed a vehicle and damaged other property. A county court judge found that an electrical defect in the vehicle caused the fire. The vehicle's finance company appealed, again without permission to challenge the primary findings.

The common question was whether each judge had impermissibly selected the least improbable explanation, contrary to The Popi M, or had properly identified the probable cause on the balance of probabilities.

1. Both appeals were dismissed unanimously. The trial judges had made permissible findings of causation on the balance of probabilities. Neither had merely selected the least improbable explanation from a group of inherently improbable causes.

2. A judge is not compelled to choose between competing theories when the evidence is unsatisfactory. The claimant then fails to discharge the burden of proof. The reasoning prohibited by The Popi M, [1985] 1 WLR 948, is the selection of the least improbable cause from a series of improbable explanations, particularly where the factual evidence is incomplete or unreliable.

3. That prohibition does not prevent a systematic comparison of plausible causes. Where the competing explanations exhaust the realistic possibilities and are not themselves improbable, the judge may eliminate one or rank the alternatives. The judge may find the remaining or most probable explanation to be the cause, provided the conclusion accords with common sense and identifies a probable cause rather than merely a relatively less unlikely one.

4. In the cyclist's claim, the only realistic explanations were that he first lost control and the handlebar then broke, or that a defective handlebar fractured during normal use and caused the loss of control. The first explanation had been rejected. The bicycle was properly maintained, had not been misused and the handlebar failed under normal loading. The evidence therefore supported the inference that the handlebar was defective and that the defect caused the accident. Under sections 2 and 3 of the Consumer Protection Act 1987, it was unnecessary to identify whether the defect arose during manufacture or through fatigue.

5. In the fire claim, the county court judge was entitled to eliminate arson as extremely unlikely. A defect in the garage electrics and a defect in the vehicle electrics were both uncommon but plausible. The sequence of events required for a garage fault to ignite the vehicle, together with the eyewitness accounts and fire-damage evidence, supported the conclusion that an internal electrical defect in the vehicle was the probable cause.

• Court of Appeal (Civil Division): In [2008] EWCA Civ 424, unanimously dismissed both appeals and upheld the causal inferences drawn below.
• Queen's Bench Division: Gray J held in [2007] EWHC 1667 (QB) that the mountain bike's handlebar was defective and that the defect caused the cyclist's injuries.
• Northampton County Court: Judge Charles Harris QC found that an electrical defect in the Lexus caused the garage fire.