So the High Court of Australia tells us at [35] in its judgment in Strong v Woolworths Ltd [2012] HCA 5 (7 March 2012) http://www.austlii.edu.au/au/cases/cth/HCA/2012/5.html handed down today. But the fact that some people also might eat them for breakfast or morning tea means that Woolworths lost the case!

Ms Strong slipped on a greasy chip in a display area just outside the "Big W" department store at a shopping centre in Taree in rural NSW. The success of her action in negligence against Woolworths as the proprietor of the area depended on the issue of causation: would the chip not have been there if Woolies had a proper system of cleaning in place? (It was conceded that they didn't, and hence that there was a breach of the duty of care they owed shoppers.)

There are main two aspects to the joint majority decision of French CJ and Gummow, Crennan and Bell JJ.

(1) The question of causation in "slipping cases" like this. In many ways this is a fairly straightforward application of principles spelled out in a number of earlier decisions. Hayne JA (as he then was on the Victorian Court of Appeal- he is now on the HCA but did not hear this appeal) is usually cited in  Kocis v S E Dickens Pty Ltd [1998] 3 VR 408, and is again here at [34]. Broadly speaking, if there should have been inspection and there has not been, then usually it will be concluded, if more than one "reasonable inspection interval" has passed, and if all else is equal, that on the balance of probabilities the failure to inspect has led to the slip. Here there was no inspection between 8 am when business opened and 12.15 when the accident occurred, reasonable inspection intervals were either 15 or 20 mins, hence it was more likely than not that the chip had been there long enough that it would have been spotted by a reasonable inspection regime. The likelihood that "lunchtime" generated more chips than the pre-lunch period was accepted, but the court took into account people's proclivity to eat greasy food at any hour and hence found in favour of the plaintiff.

(2) If this was just a slipping case it would probably have not received special leave (though in fact the Court of Appeal were found to have applied the wrong principles, so hard to say). But the complaint was also made about some comments of the Court of Appeal which seemed to reveal confusion about causation issues generally. Hard to believe that anyone could be confused about this area....:)

The confusion was evident in para [48] of the CA decision, quoted at [20] of the majority judgment. Essentially what happened was that the particular CA (Campbell JA, Handley AJA and Harrison J) seemed to draw a distinction between "but for" causation (represented in s 5D(1)(a) of the Civil Liability Act 2002 (NSW)) on the one hand, and "material contribution" on the other, and essentially seemed to equate "material contribution" to harm with "notions of increase in risk". A later decision of a differently constituted NSWCA, however, esp in the comments of Allsop P in Zanner v Zanner [2010] NSWCA 343 at [11], cited at [24] by the HCA, noted that this was wrong, and that "material contribution" can be seen as consistent with the "but for" test.

I won't bore colleagues who have heard my views on this topic at length recently and not so recently. Briefly, though, it seems to be clear that:

(1) an event A can be a cause of event B if it is part of the chain of events that are necessary for event B, even if it is not the "main" or "primary" such event;

(2) the law, and the decision in Bonnington Castings, uses the phrase "material contribution" to refer to this- A is a cause of B if it made a "material contribution" to B, even if was not the "primary" contribution;

(3) hence "material contribution" is simply a part of the orthodox "but for" analysis;

(4) but some courts (even the House of Lords and the SCC) have occasionally used this terminology wrongly and referred to "material contribution" when they mean something else. In particular "material increase in risk" is not the same as "material contribution".

So how do the comments of the majority here deal with these issues? There still seems to be some confusion. Unfortunately I see (though I don't remember noticing this before) that the confusion is contributed to by Allsop P in Zanner at [11] (cited in the HCA at [24]) saying that Bonnington Castings is a case where there was a "failure to pass the 'but for' test". I emphatically disagree with his Honour on this point. Academic support for my view can be found in the article I have cited previously on this forum, S H Bailey, “Causation in negligence: what is a material contribution?” (2010) 30/2 Legal Studies 167-185.

Sadly, however, these comments of the HCA do not resolve the confusion. At [25] they regard the situations where an "evidentiary gap" arises which needs to be filled by a "special rule" like Fairchild, as including Bonnington (or at least, they say that the Ipp Report thought this and they do not correct the misapprehension). Para [26] then suggests that s 5D(2) of the CLA (which we know was explicitly included to allow for the possibility that Australian courts might regard Fairchild as good law) might also cover "material contribution". I disagree. On a proper analysis, Bonnington was a case where the "guilty dust" was in fact necessary for the harm that eventuated (which was caused by an accumulation of dust).

They say this at [27]:

The authors of the Ipp Report and Allsop P in Zanner v Zanner assume that cases exemplified by the decision in Bonnington Castings would not meet the test of factual causation under s 5D(1)(a).  However, whether that is so would depend upon the scientific or medical evidence in the particular case, a point illustrated by the decision in Amaca Pty Ltd v Booth with respect to proof of causation under the common law[1].  In some cases, although the relative contribution of two or more factors to the particular harm cannot be determined, it may be that each factor was part of a set of conditions necessary to the occurrence of that harm.

I agree with the first sentence as a statement of what previous authors have said. I would have preferred it if the Court had simply gone on to say: "But this is wrong". Still, they leave open the possibility of that statement in the future.

For those who are following the ongoing saga of whether Fairchild is good law in Australia or not, the majority at [26] say: "we don't know yet".

Whether negligent conduct resulting in a material increase in risk may be said to admit of proof of causation in accordance with established principles under the common law of Australia has not been considered by this Court[1].