Nulty & Ors v Milton Keynes Borough Council

In a civil case concerning disputed causation, the court must decide whether the claimant’s explanation is more likely than not on a rational and objective assessment of all the evidence. Showing that one explanation is less improbable than the identified alternatives does not, as a rule of law, establish that explanation.

In evaluating circumstantial evidence, the court should consider the combined circumstances, evidential gaps, factors pointing away from the proposed explanation and other possible explanations. It must then stand back and ask whether the case for believing the proposed event occurred is stronger than the case for withholding that belief. The elimination of less plausible alternatives may support that conclusion but does not compel it.

A fire occurred at the respondent council’s recycling centre while a self-employed electrical engineer was working there. The council alleged that he caused the fire by carelessly discarding a cigarette. The principal alternative was that the fire resulted from arcing in a disused electrical cable which had remained live.

The Technology and Construction Court, in [2011] EWHC 2847 (TCC), found the arcing theory to be a remote possibility and the discarded cigarette to be the probable cause. It entered judgment for the council and rejected the insurer’s separate challenge to policy coverage. The coverage finding was not appealed.

The appellants challenged the causation decision, contending that the judge had applied an erroneous process of elimination and had misjudged the competing factual explanations. The central questions were whether the judge misstated the balance-of-probabilities test and, if so, whether his factual conclusion nevertheless remained justified.

1. The appeal was dismissed unanimously. The trial judge erred by stating that, because every other possible cause was very much less likely, the discarded cigarette became the probable cause as a matter of law. No such rule exists. Nevertheless, the error did not invalidate the factual conclusion reached on the evidence.

2. The civil balance-of-probabilities standard requires the court to be satisfied on rational and objective grounds that the case for believing the alleged event occurred is stronger than the case for withholding that belief. Expressing this as a numerical probability risks pseudo-mathematics. A court determining a past fact conducts an overall assessment of the evidence rather than assigning percentage values to possible causes.

3. A circumstantial case must be assessed as a whole. Relevant matters include gaps in the evidence, whether the individual circumstances are established, factors pointing away from the suggested explanation and other explanations consistent with the evidence. After analysing the possibilities, the court must stand back and decide whether the suggested explanation is more likely than not. Eliminating other possibilities as more implausible may produce that conclusion as a matter of fact, but does not compel it as a matter of law. The reasoning in The Popi M, [1985] 1 WLR 948, illustrated why a court may instead conclude that the party bearing the burden has failed to prove its case.

4. The trial judge was entitled to find that electrical arcing was only a remote possibility. That explanation required a combination of unsupported or unlikely events, including damage to robust cable insulation, movement of the damaged cable into contact with metalwork and an arcing sequence compatible with the timing and physical evidence. The discarded-cigarette explanation involved no comparable scientific or practical improbability.

5. An appellate court should not disturb a trial judge’s overall conclusion on a complex factual and expert assessment merely because an individual comment in a lengthy analysis is disputable. The appellant must establish serious grounds for doubting the overall conclusion. That threshold was not met. The circumstantial evidence compellingly supported the finding that the engineer discarded the cigarette, notwithstanding that such conduct appeared out of character.

1. Court of Appeal (Civil Division): The appeal was dismissed unanimously. Although the trial judge had misstated the legal effect of eliminating less likely causes, his finding on causation was properly open to him.

2. Technology and Construction Court: Edwards-Stuart J, in [2011] EWHC 2847 (TCC), held that the fire was caused by a cigarette carelessly discarded by the engineer and gave judgment for the council. He also rejected the insurer’s denial of policy coverage; that ruling was not appealed.