A woman who walked with crutches slipped on a greasy chip in a sidewalk sale area run by Big W. Nobody could say when the chip was dropped. She won at trial, lost on appeal, then took her case to the High Court of Australia. Here's what happened and why it matters.
You don't always need to prove exactly when a hazard appeared. Where the evidence runs out, a court can weigh the probabilities, and that can be enough to prove the occupier's failure caused your fall.
Ms Strong had lost her right leg and walked with crutches. While visiting the Centro shopping centre at Taree, NSW, she was approaching the Big W store at about 12.30pm when the tip of one crutch landed on a greasy chip. The crutch slipped and she fell heavily.
The chip was in a sidewalk sale area outside the store. Woolworths, which ran Big W, had the right to use that area and was responsible for keeping it safe. It had no system for regularly checking and cleaning the area that day. The last time it had been inspected was around 8am, about four and a half hours before the fall.
Nobody saw the chip being dropped, so there was no direct evidence of how long it had been there. Because this is a High Court decision, the principles it sets out bind courts in every state, including Queensland, where the test for causation in the Civil Liability Act 2003 (Qld) is in the same terms as the NSW provision the High Court applied.
Read the full judgment on AustLIIIn the District Court of NSW, the trial judge found Woolworths negligent and gave Ms Strong judgment for $580,299.12. Woolworths appealed. The NSW Court of Appeal agreed Woolworths had no proper inspection system, but said Ms Strong hadn’t proved that this failure caused her fall. Because chips are usually eaten around lunchtime, it reasoned the chip had probably been dropped shortly before she slipped, so even a reasonable system might not have found it in time.
The High Court disagreed by a majority of four to one. The majority said that when there is no evidence of exactly when a hazard appeared, a court can still decide causation by asking which explanation is more probable. The chip could have been dropped at any time between 8am and the fall. Chips are not only eaten at lunchtime, and most of that window fell well before lunchtime. On the balance of probabilities, the chip had been on the ground long enough that a reasonable inspection and cleaning system would have found and removed it.
That meant Woolworths’ failure was a necessary condition of the fall. The High Court set aside the Court of Appeal’s orders, dismissed Woolworths’ appeal with costs, and left Ms Strong’s trial judgment in place.
There was no evidence of when the chip hit the floor. Each court had to decide what the available facts made more likely than not.
The sale area was Woolworths' responsibility, but it had no regular system for checking and cleaning it. Nobody had inspected it since about 8am, four and a half hours before Ms Strong fell.
Because chips are usually eaten around lunch, the Court of Appeal decided the chip had probably only been on the floor for a short time. On that view, even a proper cleaning system might not have caught it.
The majority said there was no basis for assuming the chip was dropped just before the fall. It could have landed at any point after the 8am inspection, and most of that period was well before lunch.
Weighing those probabilities, the High Court found the chip had more likely than not been there long enough for a reasonable system to find and remove it. Woolworths' failure was therefore a cause of the fall.
These are the core principles courts apply when deciding whether an occupier's failure actually caused a slip and fall.
Under the civil liability laws in NSW and Queensland, an injured person must prove the defendant's negligence was a necessary condition of the harm. In plain terms, the injury wouldn't have happened without it.
Where nobody knows exactly when a hazard appeared, a court can compare the likely possibilities. If the explanation that favours the injured person is more probable than not, causation can be proved.
The High Court didn't shift the onus onto the shop. Ms Strong still had to prove causation. She did it by showing that, on the evidence, it was more probable the chip had been there long enough to be found.
There is no fixed national inspection interval. What counts as a reasonable cleaning and inspection system depends on the type of premises, how busy it is and the evidence in the case.
Slip and fall cases often turn on one awkward question: how long was the hazard there? Shops love to argue that nobody can know, so nobody can prove their cleaning system would have made a difference. This case shows that argument has limits. If the hazard could have appeared at any time over several hours, and the occupier wasn’t checking at all, a court can weigh the probabilities.
It’s worth being clear about what the case didn’t do. It didn’t create a national rule that every floor must be checked every 20 minutes. How often an area should be inspected depends on the place, the traffic and the evidence in each case. What the High Court did was confirm how causation can be proved when the evidence about timing is incomplete.
If you’ve been hurt in a fall, the details matter early: the time you fell, what you slipped on, photos, witnesses and any incident report. Get advice quickly, while that evidence is still available, rather than assuming your claim fails because nobody saw the hazard appear.

One conversation. No pressure. Tell us a bit about your situation and we'll be in touch.