Issues: in a labour hire/host employment scenario both liability and quantum were in issue. The parties had resolved contribution between themselves, together with the relevant duty owed. It was not disputed that the defendant’s system and place of work could have been improved or that it was not done so because of any “expense, difficulty and inconvenience”. However, causation and breach were in dispute as to whether it was reasonable to do so having regard to the risk and if the mere increase in risk warranted action.
In relation to quantum the plaintiff suffered a pre-existing degenerative back condition, which needed to be disentangled from the tortious incident.
 Whilst the defendants accepted that relevant duties were owed they put in issue both causation and breach. In the final analysis three issues were argued:
(a) The plaintiff was not injured on the day pleaded;
(b) If the plaintiff was injured on the day pleaded the forces to which he was exposed were not shown to be such as were likely to injure a person of normal fortitude. It followed that his injury was not caused by any aspect of the work system that was in breach of duty. As will be seen there are two subsidiary issues:
(i) when on the day was the onset of symptoms? and
(ii) to which of the identified risks involved in the work was the plaintiff exposed by the time of onset of symptoms?
(c) If the plaintiff was injured on the day pleaded and through breach of duty the injury he suffered was of no great consequence.
 It is convenient to look at the duties owed by an employer. The duties of a host employer may be different but it was not contended that any different result would follow if I drew any distinction between the defendants.
 Mr Stitz bases his claim on breach of the employment contract and negligence. The duty owed by an employer was explained by Windeyer J in Vozza v Tooth & Co Ltd in this way: “[F]or a plaintiff to succeed it must appear that the defendant unreasonably failed to take measures or adopt means, reasonably open to him in all the circumstances, which would have protected the plaintiff from the dangers of his task without unduly impeding its accomplishment.”
 In Hamilton v Nuroof (WA) Pty Ltd it was said that the duty of an employer is “… to take reasonable care to avoid exposing [its] employees to unnecessary risks of injury”.
 Those statements make plain, that an employer is not required to guard against all risks of injury.
 On the question of breach Mason J’s formulation in Wyong Shire Council v Shirt explains the response expected of a reasonable man, there being a foreseeable risk of injury:
“A risk of injury which is quite unlikely to occur, such as that which happened in Bolton v Stone, may nevertheless be plainly foreseeable. Consequently, when we speak of a risk of injury as being “foreseeable” we are not making any statement as to the probability or improbability of its occurrence, save that we are implicitly asserting that the risk is not one that is far-fetched or fanciful. Although it is true to say that in many cases the greater the degree of probability of the occurrence of the risk the more readily it will be perceived to be a risk, it certainly does not follow that a risk which is unlikely to occur is not foreseeable.
In deciding whether there has been a breach of the duty of care the tribunal of fact must first ask itself whether a reasonable man in the defendant’s position would have foreseen that his conduct involved a risk of injury to the plaintiff or to a class of persons including the plaintiff. If the answer be in the affirmative, it is then for the tribunal of fact to determine what a reasonable man would do by way of response to the risk. The perception of the reasonable man’s response calls for a consideration of the magnitude of the risk and the degree of the probability of its occurrence, along with the expense, difficulty and inconvenience of taking alleviating action and any other conflicting responsibilities which the defendant may have. It is only when these matters are balanced out that the tribunal of fact can confidently assert what is the standard of response to be ascribed to the reasonable man placed in the defendant’s position.”
Was the Plaintiff Injured on 9 April?
 The plaintiff commenced working at Smorgons on about 17 January 2007. The plaintiff was required to operate a Pratt cutter – a machine used to cut steel rods (or reo bars as some called them). He worked only on the Pratt cutter. He says that his back pain came on nearly three months later during his shift on Monday, 9 April 2007. There was nothing special about the work on the day in question.
 The method of operation was to select and extract a steel rod from a bundle, drop it to a conveyor table which consisted of a bed of rollers, then move the rod or rods along the rollers to the machine. The leading end of a rod as it left the end of the roller bed was intended to enter into the cutting device of the machine. The evidence was clear that that leading end could drop and miss the entry into the cutting device of the machine and strike against the machine. This happened from time to time, not every time, depending principally on the flexibility of the rods, which could vary.
 The plaintiff’s case was that, effectively, every step of this operation involved an unnecessary risk of injury. Four risks were identified:
(a) the steel rods could become entangled. If they were then it might be necessary, after selecting a rod from the bundle, to then lift and flick the rod to free it from the others. The weight taken could then be not only part of the weight of the lifted rod but also the weight of those lying on it;
(b) the force needed to move the rods along the roller bed was exacerbated by missing or stuck rollers;
(c) there could be severe jolting when the rods struck the machine if they missed the mouth of the cutter;
(d) lifting the rods into the machine when they did not enter the machine requiring significant effort.
 The plaintiff did not cease work immediately. He worked through his shift that Monday and each day until the following Friday. He said that he found that on the Thursday he could not get out of a chair after “smoko”. He reported his difficulties then to his immediate supervisor and reported the injury at the start of work on Friday 13 April.
 The plaintiff was subsequently seen by orthopaedic surgeons. Dr Wallace has expressed the opinion that Mr Stitz has discogenic back pain. Dr Boys was unable to diagnose any injury attributable to his work at Smorgons. He expressed the view that Mr Stitz experienced an episode of “degenerative low back pain.” Both surgeons thought that degenerative changes were present prior to the onset of the symptoms complained of.
 That workers’ compensation application form probably reflects the Incident Report form completed by Marie Chronopoulos, the first defendant’s representative, which also records the time of injury at 3pm. The Incident Report form is intended to reflect what the plaintiff told Ms Chronopolous. There is no other apparent source of information. Ms Chronopoulos completed the form in her handwriting then put it into typed form a short time later. The handwritten version was not produced. It was made contemporaneously with the report by the plaintiff to her on Friday 13 April. There is no reason to think that the typed version does not represent what Ms Chronopolous was told on 13 April by the plaintiff. She considered the information as to time and date of injury to be important. She impressed as a person liable to take her duties seriously.
 She records the plaintiff arriving on site at 2.50 pm to “set up to use machine” and then at 3 pm “Noticed tightness in back getting worse whilst operating the machine”. She records the activities that contributed to the incident as “Pushing, pulling, bending whilst moving feed steel into pratt machine”.
 While it is fair comment that the plaintiff may not have been greatly concerned about the precise time of injury on the application for workers’ compensation form, and it may simply have been transposed from the Incident Report, the fact is that Ms Chronopolous had no reason to misstate the time on her report. I have no doubt that it reflected her understanding of what the plaintiff had told her. It is difficult to accept that the plaintiff gave a history to Ms Chronopolous of suffering pain two to three hours into the shift and that was misunderstood by her to mean at the very start of the shift.
 Finally, it can be seen that the plaintiff’s evidence about his recollection was far from certain. He said “I seem to think it’s two to three hours into the shift” (emphasis added).
 I did not have the impression that the plaintiff was being actively dishonest. But his own evidence carried considerable doubt as to the time of initial onset and contemporaneous records from two sources strongly suggest an onset at the start of the shift. Those doubts were exacerbated by the account given in a Notice of Claim for Damages form completed some months later and which I will deal with in a moment. The probabilities favour a finding that he experienced symptoms of pain after commencing work but at the start of his shift.
 This finding creates a difficulty for the plaintiff. He does not claim to have a precise memory of what he did on the day he was injured. It is one thing to assert that working over a period of some hours it is likely that the plaintiff was exposed to all aspects of the work and so to the four identified risks. But if the discomfort that he relates happened only at the start of his shift then it is unknown what work he had done by then. The problem of entanglement did not occur every time – it could vary by chance. As well it is not known what size the rods were that he was required to work on and that has significance because the problems with entanglement at the start of the procedure and problems with the bars striking the machine just below the cutter and causing jarring of the operator each occurred primarily with the more flexible rods with the smaller diameter.
 As to the second point of attack the issue is whether the plaintiff was exposed at all on the day in question, and prior to the onset of symptoms, to the jolting that he said could occur when the leading end of the rods drooped and hit into the machine. This attack is based on the plaintiff’s earlier versions of what happened and is quite independent of the “time of shift” point but, I note, consistent with it. As I have said the plaintiff’ memory of the events of the day was far from clear. He effectively said that he followed the normal procedures. If he worked for as long as two to three hours then he would expect, in that time, that he would be subjected to the jolting from the rods striking the cutter. However, it follows from the finding that he observed the initial symptoms at the start of the day that he may not have been exposed to this jolting so early in the shift, as it occurred, on his account, only from time to time.
 It should be noted that the plaintiff does not purport to know what caused the onset of symptoms of pain in his back. However he has given at least three versions which make no reference to this jolting. This is in contrast to his evidence in chief where he expressly mentions the knocking effect in relation to the onset of his discomfort.
 The first is the version that I have mentioned above as recorded by Ms Chronopolous in the Incident Report form.
 The second is in a Notice of Claim for Damages form completed as part of the pre litigation procedures required by the Workers’ Compensation and Rehabilitation Act 2003. It is dated 20 November 2007. In a section headed “Completely describe details of the event resulting in the injury” the form records, after referring to “having to wheel the conveyor table to the Pratt machine”: “The Claimant would have to exert great effort to transfer large sized steel rods from the conveyor table to the Pratt machine”.
 It is clear that the version in this document contains, on any view, a number of inaccuracies. For example it refers to the plaintiff working the morning shift when he had never done so. And the system of work did not require that a conveyor table be wheeled to the Pratt machine. However the gravamen of the complaint about the system of work is in the words that I have quoted. The exertion of “great effort” does not correspond with being subjected to significant jolting.
 At the conclusion of the form the plaintiff was required to declare, and did, that “all statements made in this Notice of Claim for damages that are in my personal knowledge are true, correct and complete in every respect”. Plainly the plaintiff did not convey accurately to his lawyers either the events of the day or the system of work. This is one of the unexplained inaccuracies that troubles me about the plaintiff’s reliability. Nonetheless, making every allowance for the plaintiff, he could not but have realised that he was under an obligation to record those aspects of the work that he considered to be involved in his injury. He plainly did not hold the view then that this jolting had anything to do with his injury.
 The third is in a version to a Dr Steadman who saw the plaintiff for assessment. The plaintiff’s evidence on this was:
“Now, you saw, didn’t you, in relation to this claim, a doctor by the name of Peter Steadman. Do you remember seeing Dr Steadman?– I definitely do.
Right. And you told him in relation to the accident, amongst other things, that the rollers, having explained your job, were at a different level to the guillotine and so with some momentum and twisting, the rod would be pushed along, but unfortunately it would then hit the edge of the guillotine, which was uneven?– Mmm.
And that’s what you’ve told us about?– Yep.
That there were times, in fact, when the rod, after it went—–?– Yep.
—–over the last roller would droop—–?– Yep.
—–and instead of entering into the face of the Pratt machine, it would jar?– True.
And you’ve told Dr Steadman that you’d complained about this and then he goes on to say, “However, ironically, this is not how he injured himself. He said that he was pushing a rod and he thinks it was about one-quarter of a tonne when his back began to get sore. He said that the rod did not jar, but his back became sore. He kept working for another three days, however his pain became worse and worse. He said by the third day he had to stop work, because he had leg symptoms and felt that he had pressure in his low back affecting both sides.”?– Well, that’s pretty right in what he says. (emphasis added)
 I did not understand the plaintiff to deny that he had said this to the doctor. The express disclaimer to Dr Steadman that “the rod did not jar” is again against the notion that any jolting occurred, at least associated in the plaintiff’s mind with the occurrence of any discomfort in his back.
 I am conscious that the questioning by Mr Myers in cross examination conflated the issue of the cause of injury, about which the plaintiff did not pretend to know the answer, with the question of whether there was an occurrence of jarring or jolting on the day in question.
 However the state of the evidence is such that I cannot find, on the balance of probabilities, that the jolting associated with the dropping of the rods as they approached the cutting machine occurred before the plaintiff suffered any apparent injury to his back.
 It follows that the fourth of the identified risks – the need to lift the bars up that did not enter the machine – is not shown to have occurred on the day and prior to the onset of symptoms.
 That leaves then two of the identified risks as having been potentially experienced on the day and prior to the onset of symptoms – the untangling and flicking of the rods and the and the movement of the rods along the roller bed towards the cutter. The untangling and flicking was said to be more of a problem with the more flexible rods but I did not understand that it could not happen with the larger diameter rods. The movement of the rods along the roller bed towards the cutter was a constant feature of the work.
Reasonably Practical Means of Obviating the Risks
 As I have said it was not in issue that the work system and plant was plainly defective. In relation to the two identified risks that remain for consideration the evidence was plain that:
(a) the bars or rods were presented in a tangle to the workers which could have been avoided;
(b) the workers were left to work out for themselves how to go about the task of untangling rods;
(c) there was no supervision or correction of whatever technique might be adopted by a new worker for the untangling and flicking of bars;
(d) a number of the rollers that made up the roller bed and along which the rods had to be conveyed were missing or defective. There was no reason why they could not have been replaced as needed. It is evident that they were not replaced in a timely way.
(e) It was left to the workers to determine how best to move the rods.
 I am satisfied that if these matters had been remedied it is probable that the forces to which the plaintiff was exposed, and hence any risk of injury, would have been reduced. That leaves for consideration the question of whether the risk of injury that the plaintiff faced on the day in question called for any response at all.
What Were the Forces Involved?
 As I have said there was no evidence led as to the level of force imposed on the spine by any of the identified risks. In my experience that is invariably proved, as indeed it needs to be, as it is fundamental to the assessment of whether a reasonable employer should respond to the risk. Virtually any activity in life is accompanied by some risk. Hard manual labour obviously carries with it the risk of manual handling injuries. But it has never been the law that an employer must remove all risk of injury. And appeals to general principles such as that the standard of care expected of an employer is high does not fill the evidentiary gap.
 As French CJ and Gummow J said in Kuhl v Zurich Financial Services Australia Ltd
“To satisfy the element of causation … it would be necessary to identify the action which, on the available evidence, the trial judge could conclude ought to have been taken; that action, if failure to take it is to be accounted negligent, must be such that the foreseeable risk of injury would require it to be taken, having regard to the nature of that risk and the extent of injury should the risk mature into actuality; and it would be necessary that the trial judge could conclude as a matter of evidence and inference that, more probably than not, the taking of that action … would have prevented or minimised the injuries the plaintiff sustained.”  (my emphasis)
 If the forces involved were at a level not likely to injure a man of normal fortitude then the fact that those forces could have been reduced so as to be even less likely to injure such a man does not establish a need to act. A failure to take such measures does not connote negligence in an employer.
 What then is the end result of this evidence?
 It is not known what gauge steel rods were processed by the plaintiff at the start of the shift on the relevant day. The smaller the gauge the more likely the degree of entanglement and conversely. The amount of weight taken was estimated by Mr Batley at three-quarters of the weight of a bar plus the weight of any rods that may have been resting on the rod selected. Obviously a worker would endeavour to pick a rod from the top of the pile or the least entangled. Whether the plaintiff was confronted with the problem of entanglement on the day in question and prior to the onset of his symptoms is unknown. Whether the worker Mr Batley observed on 31 July was performing the work in the fashion that the plaintiff did on 9 April and on bars of the same dimensions is unknown. Mr Batley’s description of a two handed lift above the right shoulder does not match the plaintiff’s account of his method.
 The mass of the bars that were required to be pushed along the roller bed could be in the vicinity of 210kgs or as low as about 78 kgs. The pushing along the roller bed required an unidentified force to be exerted on the spine. The coefficient of friction of steel on steel in this situation is not proved. It would plainly reduce and, I suspect, considerably reduce the effort required to move the mass. So much would be consistent with the evidence of Simonds and Bashford. What mass the plaintiff pushed before the onset of his symptoms is unknown.
 There were an unidentified number of rollers that were defective or missing. Mr Simond’s point that the location of these missing or defective rollers was of significance was not shown to be wrong. The location of the dozen rollers checked by Mr Batley is not established. Mr Simonds had great experience with the roller bed. He had checked the machine on the morning of the day the plaintiff was injured. He presumably complied with his own criteria of relocating missing or defective rollers so as to minimise their effect.
 Whatever the exertion involved it was required of the plaintiff on an unknown number of occasions before the onset of symptoms.
 The lay witnesses were in conflict as to the degree of force involved in the work. Both the plaintiff and Mr Bosel were inclined to over state the case.
 Mr Batley was concerned with enforcement of the provisions of Workplace Health & Safety Act. The test that he had to consider was whether the employer had ensured workplace health and safety. That is not the common law test. Unsurprisingly he found the workplace to be unsatisfactory. He determined that there was a risk of musculo-skeletal injury. That opinion does not seem to me to take matters very far. Any manual handling task involves a risk of musculo-skeletal injury. The question here is the extent and likelihood of injury. What he had in mind is unexplained.
 I am satisfied that there were measures available to the employer, reasonably open to it in all the circumstances, that would have reduced the risk of injury. Those measures would not have unduly impeded the performance of the work. What I do not know is whether the adoption of such measures would probably have protected the plaintiff from the risk of injury.
 While it is reasonable for the plaintiff to argue that he was exposed to work that had the potential to injure his back, and that the inference should be drawn that the work caused his injury, whatever be its character, it does not necessarily follow that work in breach of duty caused his injury.
 In Neill v NSW Fresh Food & Ice Pty Ltd Taylor and Owen JJ said:
“in many cases no more than common knowledge, or perhaps common sense, is necessary to enable one to perceive the existence of a real risk of injury and to permit one to say what reasonable and appropriate precautions might appropriately be taken to avoid it.”
 While Mr Simond’s evidence of long use of the machine without injury does not result in a finding that there was necessarily no relevant risk of injury, it does in my view prevent any perception of the existence of “a real risk of injury” by the application of common sense and precludes a necessary finding, without more, that some action ought to have been taken.
 In Betts v Whittingslowe Dixon J said:
“Breach of duty coupled with an accident of the kind that might thereby be caused is enough to justify an inference, in the absence of any sufficient reason to the contrary, that in fact the accident did occur owing to the act or omission amounting to the breach of statutory duty.”
 However for reasoning of that kind to apply the facts proved need to be compelling. As Dixon J said of the evidence in Betts “the facts warrant no other inference inconsistent with liability on the part of the defendant”.
 In my view the facts do not warrant that inference being drawn here. Here the plaintiff was engaged in manual work. Such work has a capacity to injure – particularly if one has a degenerate back, as did the plaintiff. That would be irrelevant if it were shown that the work that the plaintiff performed exposed him at the material time to forces that were at a level likely to injure a man of normal fortitude. But that is not shown.
 The approach to take to causation in negligence suits was recently discussed by French CJ and Gummow J in Kuhl v Zurich Financial Services Australia Ltd. Of present relevance their Honours mentioned Hamilton v Nuroof (WA) Pty Ltd in these terms:
“That case concerned the duty of an employer to adopt a safe system of work. The decision has been said to indicate that it may be unnecessary for a plaintiff to show exactly how the injury occurred if there be a defect in the system of work and it is clear that the injury arose out of the defective system.”
 Here it is shown that the injury occurred against a background of a defective system of work but it is not “clear that the injury arose out of the defective system” in the sense of being caused by it.
 The plaintiff submitted that the decision of the High Court in Amaca Pty Ltd v Ellis supported his assertion that an inference should be drawn that the injury sustained was caused by the negligence of the defendants. There the question was whether the plaintiff had demonstrated, where scientific certainty was impossible, that the negligence of the defendant had caused lung cancer through exposure to asbestos. The relevant point however is that the plaintiff there disavowed:
“any argument in these appeals that demonstrating only that the exposure to asbestos increased the risk of contracting lung cancer was sufficient to establish causation.”
 Here the plaintiff has shown that there may have been an increased risk of injury given the way the defendant conducted its works but that does not necessarily demonstrate that its actions in breach of duty did in fact cause the injury.
 In my view the plaintiff has not established that any breach of the common law duties owed has caused any injury.
 Dr Wallace held the view that the plaintiff did sustain an injury at work. When cross examined as to why he held that view he replied:
“And what leads you to a different conclusion to Dr Boys conclusion?– That was based on the history given to me by Mr Stitz, in which he – in which when I interviewed him on the 6th of December 2007, he gave a history of a specific work related injury to his lower back. And that was when he was – he told me that he was cutting reo in a guillotine.”
 And later Dr Wallace again stressed that his view was formed because “the history given to me was that he injured his back whilst cutting – guillotining reo.” He formed that view because “an event which occurred has been a significant contributing factor to his current disability.”
 That last comment tends to beg the question.
 It has been said that “a prime duty of experts in giving opinion evidence: [is] to furnish the trier of fact with criteria enabling evaluation of the validity of the expert’s conclusions” The criterion that Dr Wallace relies on, to the extent that it is revealed at all, is flawed. The plaintiff does not give a history of “a specific work related injury to his lower back” as Dr Wallace assumed. A history of discomfort one day but with an ability to do hard manual labour for the next three days before the onset of severe symptoms at around smoko on the fourth day is not the same as the history that Dr Wallace has assumed.
 Whether adoption of the history that the plaintiff gave in evidence and now says is accurate would permit Dr Wallace to maintain the same opinion or cause him to alter his views was simply not explored. If anything Dr Wallace seems to be drawing comfort from the temporal proximity of the onset of significant symptoms to the work injury he assumes. That temporal proximity is more tenuous than he supposed. Whether the discomfort that the plaintiff spoke of as initially occurring and the continuing ability to carry out hard manual work of the type that the plaintiff did for the next few days is consistent with the injury that Dr Wallace assumes occurred on 9 April is far from clear.
 The difficulty that this presents is that Dr Wallace’s opinion does not have a “rational relationship with the facts proved” as it is not based on a sufficiently accurate assumption of fact. In Makita (Australia) Pty Ltd v Sprowles Heydon JA said:
“The basal principle is that what an expert gives is an opinion based on facts. Because of that, the expert must either prove by admissible means the facts on which the opinion is based, or state explicitly the assumptions as to fact on which the opinion is based. If other admissible evidence establishes that the matters assumed are “sufficiently like” the matters established “to render the opinion of the expert of any value”, even though they may not correspond “with complete precision”, the opinion will be admissible and material: see generally Paric v John Holland Constructions Pty Ltd  2 NSWLR 505 at 509-510; Paric v John Holland Constructions Pty Ltd  HCA 58; (1985) 59 ALJR 844 at 846. One of the reasons why the facts proved must correlate to some degree with those assumed is that the expert’s conclusion must have some rational relationship with the facts proved.”
 In my view the history that Dr Wallace has assumed and that forms the basis of his views is not “sufficiently like” the history that the plaintiff now gives to justify acting on Dr Wallace’s evidence.
 That being so all that can be found is that the plaintiff has experienced a modest temporary aggravation of a degenerate back condition as a result of the work performed on 9 April.
 I am conscious of the plaintiff’s account of the pain increasing from Monday through to Thursday and then the problem getting out of the chair at around 6 pm on Thursday when he had “excruciating pain” and that he struggled to finish the Thursday shift. There are many cases in which histories of this type have been analysed by expert medical witnesses and hypotheses in favour of causation of a significant back injury drawn. But there are two problems here. First, there is no medical evidence on which to base a finding of a causal relationship between a discal injury of some sort and the work on the Monday and in my view that is essential. And secondly, that would require an uncritical acceptance of the plaintiff’s account of his symptoms over those few days. I do not feel able to do that. Quite apart from his presentation in the witness box, which did not inspire confidence in the reliability of his recollection, he has the significant difficulty that he has given a number of out of court versions that do not contain this history. Added to that is the improbability of the plaintiff working in this work, which on any view was reasonably significant manual labour, for three days with a discal injury without complaint and, so far as the evidence shows, without any other worker noticing.
 As neither doctor had an accurate history it is not possible to be remotely precise about the extent or duration of the modest temporary aggravation that I have found.
 Doing the best I can I assess damages at $2,000.
Brisbane Barrister – David Cormack