A reminder that just because a serious accident happens at work does not necessarily mean that breach and causation will be established. Competing probabilities that lead to conjecture is not enough.
Macfarlan JA with whom Barrett and Leeming JJA concurred:
21. Logically, and consistent with the primary judge’s approach, examination of the issue of negligence must be preceded by a consideration of what caused the accident.
22. In examining an issue which provides the foundation for a finding of negligence, it is necessary for the Court to reach “a definite conclusion affirmatively drawn” (Jones v Dunkel  HCA 8; 101 CLR 298 at 305). It is not enough if the evidence gives rise only to “conflicting inferences of equal degree of probability so that the choice between them is [a] mere matter of conjecture” (Jones v Dunkel at 304-5 citing Bradshaw v McEwans Pty Ltd (1951) 217 ALR 1 at 5; see also Luxton v Vines  HCA 19; 85 CLR 352 at 359-360; Condos v Clycut Pty Ltd  NSWCA 200 at ; and Minogue v Rudd  NSWCA 345 at ).
31. On Mr Kiem’s theory, the occurrence was a rare, unforeseeable event. Neither expert suggested that any step the respondent could reasonably have taken would have avoided the accident occurring if it was caused as Mr Kiem described.
32. On Mr O’Brien’s theory, the risk of malfunction due to wear was foreseeable. However, the evidence did not establish that any step that a reasonable person in the respondent’s position would have taken would have detected the wear prior to the accident. Mr O’Brien accepted in cross-examination that in the absence of knowledge of a problem with the operation of the clutch, ordinary maintenance services, other than the 10 year and 25 year major services, would not have identified the wear to which he referred (Transcript p 103). Only in those services would the clutch valve be removed and checked.
33. As the subject crane was 24 years old, it had not yet reached the time for its 25 year service. Although Mr O’Brien was not able to find any record that the crane had undergone a 10 year service, that is not a sufficient basis for inferring that it had not, particularly in light of the change of ownership which occurred in the meantime. In any event, Mr O’Brien accepted in cross-examination that the wear in the valve that he thought was significant may well not have been present or visible at the time of the 10 year service (Transcript p 107).
34. As to any knowledge of the respondent that the crane was not operating normally, I refer to  and  above concerning Mr French’s interview and the evidence at  above that slow leakage is commonplace with old cranes.
35. As a result, on neither theory of the cause of the accident was causative negligence proved.
David Cormack – Brisbane Barrister & Mediator