High Court Decision in Strong v Woolworths – ‘probability theory’ vs common experience


Plaintiff personal injury lawyers are all agog over the recent High Court decision of Strong v Woolworths [2012] HCA 5. But has it really moved things much in their favour or was it simply a case of the best possible response to a difficult set of facts?

The facts themselves are straightforward: in an unfortunate accident, an amputee woman on crutches slipped on a hot chip dropped on the sidewalk of a shopping centre, which was property under the care and control of Woolworths. On the evidence, there was no way of determining when the chip had been dropped but it was agreed the accident took place at 12.30pm.

Woolworths conceded that it had no proper system of inspection in place to prevent this kind of accident, but argued that even if it did, the errant chip would not have been detected in time to prevent the accident.

This argument raised the question of causation under section 5D of the Civil Liability Act: was Woolworths’ negligence in failing to have a proper system of inspection and cleaning in place the cause of the harm suffered?

A key step in the reasoning process adopted by the majority of the High Court was to determine that a reasonable system of ‘inspection and removal’ would require intervals between checks of not more than 20 minutes.

Therefore, for Woolworths to succeed the Court would need to find that the chip was dropped after the time of the last hypothetical inspection at 12.10pm. If so, the argument holds true that the chip would not have been detected by the time of the accident at 12.30pm, regardless of whether or not there was a proper system of inspection in place.

Conversely, if the Court determined that the chip was dropped before 12.10pm the Woolworths argument would be defeated and the plaintiff would be entitled to succeed.

Given the supermarket had been open since the start of normal trading hours, the plaintiff’s counsel argued that by sheer dint of comparing the time frames involved, the chip was more likely to have been dropped in the period between 8am and 12.10pm rather than the much shorter period between 12.10 and 12.30pm.

This argument had been defeated in the NSW Court of Appeal decision by one based more upon common sense and experience than numbers. In the court below Woolworths’ counsel, Mr Maconachie QC argued that as hot chips are more likely to be eaten at lunch, and there are more people around at that time generally (among whom, there are presumably those eating hot chips), the chip was more likely to have been dropped in the period closest to lunchtime (ie- between 12.10 and 1230pm). That’s the beauty of the common law, it’s perhaps one of the last jurisdictions left where common sense and experience have a chance to have their say.

Each of these two reasoning processes (common experience vs numbers) have their difficulties but the NSW Appeal Court judges chose common experience. However, the majority of High Court overturned the Court of Appeal and went for the odds (at [38]):


“The probabilities favoured the conclusion that the chip was deposited in the longer period between 8am and 12.10pm and not the shorter period between 12.10pm and the time of the fall.”


Perhaps the High Court felt that to permit Woolworths to escape liability in the face of no proper inspection system would prevent justice being done.

In his dissenting judgment Justice Heydon took a more hardline approach – as the plaintiff hadn’t positively discharged the burden of proving her case she should lose. This seems in keeping with the requirements of section 5E of the Civil Liability which states that the plaintiff bears the onus of proof.

In other words, it was for the plaintiff to prove via the evidence that the chip was dropped before the moment at which the last hypothetical inspection prior to the accident would have taken place, and that her recourse to “probability theory” in attempting to do this was “unconvincing”. His Honour thought the plaintiff needed more than just favourable odds to make out her case.

It is rare that there will be no evidence at all before the court on a matter so crucial. Both the NSW Court of Appeal and High Court were faced with a difficult choice between what some might consider the lesser of two evils; both common sense and probabilities are an inexact means of deciding such a serious and unfortunate situation.

If there was anything more substantial in evidence the case would not have gone nearly this far, which begs the question whether the decision will be treated as one limited to its facts or whether it will see the unlikely proliferation of reasoning based on “probability theory” in our court system. Only time will tell.


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Filed under causation, Negligence

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