This is another addition to my ‘The Rule In’ list of standard legal maxims.
It is my experience that in negligence cases where there is no other obvious explanation for an accident other than the fault of the defendant, a plaintiff will allege res ipsa loquitur. It masquerades as the perfect case for a plaintiff. Properly applied however, it’s anything but a cinch.
A recent treatment of the applicable principles by McCallum J in Holberts Oyster Supplies P/L v Stephenson  NSWSC 425 illustrates this point.
The first thing to know about res ipsa is that it is not a rule of law but rather a process of inferential reasoning to bring about factual conclusions. Therefore, whether or not it was engaged in correctly may not even be appealable, it being in all likelihood a question of fact. McCallum J raised this doubt at [19-20], but settled on it being a mixed question of fact and law, for which leave was required (and granted).
In Holberts, the plaintiff’s truck collided with a spare wheel that had broken free from where it was stored beneath a trailer towed by the defendant’s truck. At first instance, there being no other evidence upon which a finding of negligence against the defendant could be made, the plaintiff’s case relied heavily upon seeking to have the Magistrate draw an inference on the basis of res ipsa loquitur. The magistrate rejected this approach and the plaintiff appealed, alleging the Magistrate she had done so incorrectly.
MacCallum J reviewed the key authorities on the doctrine and at  refined the principles to the following three:
(a) the cause of the incident must be unexplained;
(b) the incident must be of such a kind that, in the common knowledge and experience of mankind, it does not ordinarily occur without negligence;
(c) the things that caused the incident must be in the exclusive control of the defendant.
By reference to more of the authorities her Honour also pointed out that satisfaction of the above test still doesn’t get the plaintiff home by say, creating a rebuttable presumption that the case is made out. At  her Honour says:
Ultimately, however, any inference to which the principle gives rise is but one factor to be taken into account along with the other evidence in the matter.
Returning to the facts of this case, on its face, reliance upon res ipsa loquitur might have seemed attractive. Why else other than the defendant’s failure to have it properly secured would the wheel have fallen free from the underside of the trailer?
But the trial judge disagreed. The causal component of the case was not so straightforward. That is, the plaintiff’s case failed at the second hurdle, it being decided that this was not such a simple matter, ie. not a matter that within common knowledge and within the experience of mankind, only explicable by negligence.
In fact the trial judge proffered a number of other alternatives: faulty ropes securing the wheel, its T-bar not being properly secured, a crack in the T-bar, something on the road that came into contact with the tyre rack causing friction or even a latent defect not discoverable on visual inspection (of which there was evidence two weeks prior to the accident).
In referring to this part of the magistrate’s judgment, her Honour MacCallum J found the trial judge had more than adequately applied the principles applicable to a res ipsa inference and so was confident to dismiss the appeal.
What at first seemed quite an attractive way home for the plaintiff in the end proved calamitous.