(Written submissions - 10, 11, 21, 22 December 2015)

Workers' Compensation - Entitlement to compensation - Injury, disease or disability - Disease - Aggravation or acceleration of pre-existing disease or condition - General principles - "Injury" where employment the major or most significant contributing factor to recurrence, aggravation, acceleration, exacerbation or deterioration of pre-existing disease - Nature of underlying progressive disease not excluded from consideration as a contributing factor - Correct approach where pre-existing disease is progressive in nature.

Murray v Shillingsworth [2006] NSWCA 367; (2006) 68 NSWLR 451, considered.

Cook v Midpart Pty Ltd t/as McDonalds Forster [2008] NSWCA 151, followed.

Federal Broom Company Pty Ltd v Semlitch [1964] HCA 34; (1964) 110 CLR 626, applied.

Workers' Compensation - Proceedings to obtain compensation - Determination of claims - Appeals, judicial review and stated cases - Question of law - Appeal where party agreed by determination in point of law - Generally - Content of statutory duty to provide reasons for determination - Failure to state essential findings of fact - Failure to make such findings - Error of law established.

Gulf Industries v Barnett (1996) 6 Tas R 142, applied.

Judgment Number: [2016] TASSC 6

1. This is an appeal from a decision of the Workers Rehabilitation and Compensation Tribunal made on 21 October 2014. The Tribunal was constituted by the Chief Commissioner, Mr Carey. (It is more convenient to simply refer to the "Commissioner".) The Commissioner had before him a disputed claim for compensation. The worker, Mr Long, alleged that he suffered an injury to his lower back in the period of 1 to 2 March 2013, occurring in circumstances which entitled him to compensation. Mr Long was employed by Kmart Australia Ltd as a motor mechanic.
2. It was common ground that Mr Long had been incapacitated for work from the time of the alleged injury. There was no agreement that Mr Long was entitled to payments of compensation in any form, but the question for the Commissioner was restricted to Mr Long's entitlement to weekly payments. It was also common ground that Mr Long had a pre-existing lower back condition in the form of degenerative changes with "osteophytic changes" mostly affecting the L5/S1 disc; sometimes referred to in the evidence as "degenerative lumbar spine disease".
3. In summary, Mr Long's evidence was that during the afternoon of 1 March, while changing a engine timing belt, he became aware of lower back pain. This continued overnight and into the next day when at work. At some time in the morning whilst at work he says he suffered a worsening of pain and discomfort when he got off a stool. This incident was later reported to his employer. After the incident however, he continued to work and finished at about 2pm. Mr Long described episodes of increased pain when he was driving home. When he arrived home and attempted to get out of his car, he felt very significant pain and loss of mobility.
4. Subsequent medical examination revealed a broad-based disc bulge at L5/S1 level "with superimposed central/right para-central disc protrusion". Following conservative treatment, on 19 July 2013, Mr Long underwent a posterior lumbar inter-body fusion at L5/S1 level.
5. The Commissioner said that three questions arose from the evidence. They were:

"(a) Did the worker suffer an injury, if so what injury, in the course of his employment on 1 or 2 March 2013?

(b) Did the worker suffer an injury (which was a disease) in the course of his employment and to which his employment was the major or most significant contributing factor?

(c) Did the worker suffer an aggravation or exacerbation of an underlying disease on 1 or 2 March 2013 to which his employment was the major or most significant contributing factor?"

1. The Commissioner decided that the answer to all three questions was "no". It is primarily the determination in respect of the third question which is the subject of this appeal. There is no direct challenge to the determination of question (a), but Mr Long seeks to identify errors in the approach to that question said to be relevant to question (c). Question (b) does not need to be considered. It seems that question (c) was put as an alternative to (a), and I am not sure why (b) is listed as the second question. For the following reasons, I have reached the view that the appeal should succeed.
2. At this point it is convenient to set out the relevant provisions of the Workers Rehabilitation and Compensation Act 1988 (the Act).
3. Section 25 of the Act provides as follows:

(a) a worker suffers an injury, not being a disease, arising out of or in the course of his employment; or

(b) a worker suffers an injury, which is a disease and to which his employment contributed to a substantial degree, within the meaning of section 3(2A) -

his employer is, except as is otherwise provided by this Act, liable to pay compensation in accordance with this Act ...".

1. Section 3(2A) provides that for the purposes of the Act, employment contributed to a disease to a substantial degree only if it is the major or most significant factor. The word "injury" is defined in s 3(1) of the Act as including:

(b) the recurrence, aggravation, acceleration, exacerbation or deterioration of any pre-existing injury or disease where the employment was the major or most significant contributing factor to that recurrence, aggravation, acceleration, exacerbation or deterioration - ...".

1. It is par (b) of this definition which is the focus of the arguments in this appeal. In particular, the argument in relation to the third question is whether Mr Long suffered an aggravation or exacerbation of his pre-existing disease where his employment was the major, or most significant contributing factor to that aggravation or exacerbation.

1. The Commissioner's reasons are relatively lengthy. Because of the terms of the grounds of appeal, it is necessary to deal with them in some detail. Before setting out the reasons for resolving the third question in favour of Kmart, it is necessary to set out the essential facts as described by the Commissioner and the way in which he dealt with the first question. As to the facts, the Commissioner said:

"3 The Tribunal accepts the worker's evidence (which was not challenged) that during the afternoon of 1 March 2013 whilst carrying out his work as a motor mechanic and more specifically whilst engaged in changing an engine timing belt on a Hyundai Lantra he became aware of low back pain. This was in the form of a 'constant low pressure pain' in a strap like distribution across his lower back. This pain stayed the same, and affected the same level of his back during the rest of his work day and that night at home. The pain during this period was assessed by the worker at a base rate of 2 out of 10. The next morning and when he arrived at work the nature, distribution and level of his pain remained the same. There is then an alleged activity that caused what the worker asserted in evidence to be a transient but significant change in his back symptoms; this incident shall be referred to as the 'stool incident' and as it is in dispute I will deal with it later.

4 After the stool incident the worker's symptoms returned to what he described as the base level at 2 out of 10. He worked that day his rostered hours and concluded at approximately 2:00pm. Save for the transient change following the stool incident his back symptoms remained at the base level as to nature, distribution and level of pain throughout that day and were at that level when he commenced his journey to his home driving his motor vehicle. There is then disputed evidence as to the circumstances of the change in his back symptoms during and at the completion of that journey.

5 In any event, subsequent to his arrival at his home there was a significant and graphic change in the level and nature of his symptoms. He describes intense stabbing pain with a significant loss of mobility due to pain. A radiation of pain affecting the right buttock and right leg also developed. Subsequent medical treatment occurred, initially conservative, and radiological scans identified that he had suffered, in summary, a L5/S1 broad based disc bulge with superimposed central/right para-central disc protrusion."

1. As to the "disputed evidence" referred to in par [4] of the reasons, Mr Long gave evidence of a sharp increase in pain levels when negotiating two particular roundabouts on the drive home. He was not challenged about that, but there was a dispute about what his specific actions were when he went to get out of the car. That concerned whether he went to twist to get out and could not, or he actually twisted his body. The Commissioner did not resolve that dispute.
2. Two medical practitioners gave evidence; Doctors Michael Jackson for Mr Long, and Dr David Ruttenberg for the employer. Mr Long tendered two reports of the treating surgeon, Mr Arvind Dubey. Given the evidence, it is useful to set out the Commissioner's approach to question (a). He noted that there was no evidence of any incident or event which occurred at or around the time that the back symptoms commenced on 1 March 2013. The Commissioner noted Mr Long's evidence that in the middle of the afternoon he noticed lower back symptoms, describing these as "old man pains". The Commissioner's impression of Mr Long's evidence was that the symptoms merely developed while he was working, with no particular aspect of his work identified as initiating the symptoms.
3. I interpolate that the evidence showed Mr Long as having experienced symptoms in the past, although there was a dispute about their extent and effect. The evidence was that a CT scan in May 1995 showed a mild generalised bulge of the particular disc. A further scan in June 2000 showed what was reported as "a moderate sized focal right paracentral disc protrusion". There was impact on the right S1 nerve root sheath. An MRI scan of 5 March 2013, after the relevant events, showed a generalised disc bulge with a small right central disc protrusion. That protrusion abutted the right S1 nerve root "causing possible root irritation".
4. The Commissioner went on to deal with the evidence of the medical practitioners. As to Dr Jackson's evidence, he stated as follows. Dr Jackson in his report of 17 March 2014 inferred that when the symptoms commenced, the worker suffered an injury at work. In that report, Dr Jackson said that, against a background of pre-existing degenerative change in his lumbar spine, as a consequence of his employment (working in a confined space on a motor vehicle for a prolonged period of time) Mr Long suffered a discogenic injury to the L5/S1 disc - a specific injury to his lumbar spine, not a disease. Dr Jackson's evidence, the Commissioner said, "lost clarity" in the course of cross-examination and re-examination. In cross-examination, Dr Jackson eventually accepted that as at the date of the worker's injury he had significant degeneration of his lumbar spine at the L5/S1 level, and that this had progressed over many years.
5. As to causation, the Commissioner referred to Dr Jackson's view that the pain had initially started at work and accordingly the final result was consequential of that work. Dr Jackson accepted that it was a reasonable inference that as the worker attempted to get out of his car the disc ruptured and the nerves were compromised, leading to the increase and change in pain symptoms. Dr Jackson concluded that the disc partially prolapsed at work and then "bang, it goes" when he attempts to get out of his car with the end point being when the sciatica occurs. In re-examination, he maintained that the start of the relevant pathology was when the pain first commenced at work.
6. The Commissioner noted Dr Dubey's opinion in his report of 23 January 2014 that he would consider the situation more one of degenerative lumbar spine disease where the worker's employment had contributed to a substantial degree. The Commissioner observed that Dr Ruttenberg also did not accept that an injury occurred. Dr Ruttenberg said in his report of 17 May 2013, that there was no evidence that suggested Mr Long suffered an acute bony or new discal injury by virtue of tasks and postures adopted by him in his working environment; it was more likely that the disc osteophyte and protrusion complex had been present over many years, and it was more probable, given the history and radiological changes, that Mr Long had simply aggravated what was already present. The changes appeared more to be of natural progression of what was already present, and made symptomatic.
7. The Commissioner went on to say that he was not persuaded that "an injury occurred to the worker in the course of his employment on 1 March 2013". [My emphasis] The Commissioner said, "The injury was a prolapsed disc and the full effect of this was not apparent until the worker attempted to alight from his car when he arrived home on 2 March 2013". I set out a summary of what follows those statements, but adopting the Commissioner's words from par [17] of his reasons:

"• The back symptoms suffered during 1 and 2 March 2013 at work (save for the stool incident) were not suggestive of a prolapsed disc.

• Dr Jackson relied on a system of work involving prolonged work in a confined space, with lifting and twisting; being that it was heavy work. This was not an accurate understanding of the work system.
• The work being performed on the relevant days did not involve any prolonged period working in a confined space; there may have been some lifting and twisting, but there was also the opportunity to alter posture regularly during the course of performing any specific duty.
• The question is not whether the system of work could have resulted in an injury but rather a determination on the balance of probability whether what the worker was doing on the relevant days did in fact cause an injury.
• There was no evidence of a particular incident or event that caused the onset of pain; the evidence was of gradual onset.
• Dr Jackson's opinion was that the injury process commenced when the pain started, and there was then a 'rolling process' until the end state of the disc prolapse, which description was "of a developing condition more akin to a disease as described in the definition of 'disease'[1].
• When 'taken to the concept of disease', Dr Jackson accepted that in the background of the pre-existing degenerative back condition, the work engaged in by Mr Long on the relevant days, together with his driving home on 2 March 2013, 'was the significant cause of the aggravation or exacerbation of his underlying condition'."

1. As I have said, there is no direct challenge to the determination of question (a). However, Mr Long is critical of some aspects of the reasoning process as they are said to be relevant to the approach to the question of an aggravation in the determination of question (c). The first argument is that when considering the question of injury simpliciter, the Commissioner failed to make specific findings of what it was that Mr Long physically did in carrying out his work, particularly over the two days. Mr Long says such findings were necessary in order to assess the nature and degree of stresses on the low back and to consider the question of physiological change to the disc. It is submitted that all that the Commissioner said was that the work did not involve prolonged working in a confined space; and that there may have been some lifting and twisting; the Commissioner's understanding being that it was not heavy work. As observations on the reasons, they are correct.
2. As an aside, I add that it seems clear that question (a) is meant to relate to s 25(1) of the Act. I am not sure how it came about, but question (a) is framed in terms which exclude reference to "arising out of". The Commissioner said that the three questions arose on the evidence, but I cannot see a reason for the first issue to be so defined. It is trite that the word "or" in s 25(1) is truly disjunctive, and that the two limbs are alternative pathways to liability.
3. In any event, Mr Long further argues that in the context of looking at question (a), the Commissioner accepted that symptoms from the stool incident were suggestive of a prolapsed disc: see the first dot point in par [17] above. It is said to follow that this should have informed the inquiry as to an "injury" within the par (b) definition. As to this however, it seems to me that a fair reading of the reasons overall shows that the expression "save for the stool incident", in its context, might at least equally mean that the Commissioner excluded symptoms from that incident from consideration.
4. As to question (b), the Commissioner said that he was not satisfied that Mr Long's employment over about three years with the employer caused the identified degenerative back disease. He went on to deal with question (c):

"19 A final question to be answered concerns the proposition that the worker's employment activities over the period of 1 and 2 March 2013 and in particular at the time the pain symptoms commenced aggravated or exacerbated his pre-existing degenerative back condition so as to constitute an injury within the definition in s3. ...

20 In closing submissions the worker's case was put on the basis that the end result was a product of the exacerbation or aggravation of a disease. There was no reference in the evidence or in submissions addressing whether this was an acceleration or deterioration circumstance and accordingly there is no basis for the Tribunal to consider same. What arises from the evidence is whether the final resultant condition that resulted in incapacity, that being the disc prolapse, was the end result of an aggravation/exacerbation of the worker's disease or whether it was a separate event not causatively linked to the requisite degree to the worker's employment, perhaps as a separate injury or the naturally occurring end result of the non-work caused degenerative condition." [My emphasis.]

1. The Commissioner said that to determine the final question it was necessary to outline further relevant findings of fact that bore on the matter. They are as follows. The worker's prior history of incidents of back pain were indicative of an underlying and progressing degenerative back condition, and not separate and unrelated incidents of muscle pain or non-specific back pain. It was to be inferred that the worker was aware that these previous incidents related to some form of back or disc pathology. Mention of the "stool incident" arose in the evidence but was not considered in forming the opinions expressed by Dr Jackson and Dr Dubey. There was some form of pain/discomfort when the worker got off the stool on the morning of 2 March 2013, as he apparently reported it to his employer later on 2 March. However, the stool incident did not cause a dramatic change in the worker's back symptoms, but was merely an incident of the ongoing pain and mobility restrictions he had suffered from on the afternoon of 1 March. No appreciable weight is to be given to the incident as the worker did not tell Dr Jackson about it, nor apparently, Dr Dubey.
2. The Commissioner then considered the meaning of the words "aggravation" and "exacerbation". He noted that in Federal Broom Company Pty Ltd v Semlitch [1964] HCA 34; (1964) 110 CLR 626 at 634, Kitto J said in considering the term "aggravation, acceleration, exacerbation or deterioration" of a disease, that the four substantives are not synonymous with each other, and a court should assume that it is for the differing shades of meaning of which they are susceptible that the draftsman has chosen to employ them all. The Commissioner set out Kitto J's statement that the word exacerbation as applied to a disease "is properly used to refer to the effect which the disease produces in the victim rather than the advance of the disease itself to a more serious stage of its development". The passage from the judgment of Kitto J which the Commissioner set out, also contains approval of the statement of Moffitt J in the court below, that:

"There is an exacerbation of a disease where the experience of the disease by the patient is increased or intensified by an increase or intensifying of symptoms. The word is directed to the individual and the effect of the disease upon him rather than being concerned with the underlying mechanism."

1. The Commissioner went on to consider the meaning of the word "aggravate". He quoted a statement by Windeyer J in Ogden Industries Pty Ltd v Lucas [1967] HCA 30; (1967) 116 CLR 537 at 593, that aggravation means that an existing disease "has been made worse not that it has simply become worse". The Commissioner referred to a discussion by Rendit J in Harding v CIC Workers Compensation (Vic) Ltd v Transwest Haulage Pty Ltd [1995] VCC 30 of the meaning of "aggravate". That discussion was by way of reference to dictionary definitions which gave meanings such as "to increase gravity (of illness)" and "to make worse, more severe or less tolerable". The Commissioner concluded as follows:

"26 Consideration of the above leads me to accept that the use of the term 'exacerbate' is a reference to the effects of the disease upon a person rather than an advancement or identifiable change in the disease itself. This term is capable of applying to the onset of pain described by the worker as the base level 2 out of 10 and the pain affecting him throughout his time at work from mid-afternoon on 1 March 2013 until he concluded his work on 2 March 2013. It is not capable of application to the disc prolapse which upon the evidence is open to be described as an advancement of the degenerative disease to a more serious stage or level.

27 It is possible to consider that the prolapsed disc upon the background of degenerative back disease was an aggravation of that disease as that happening made the disease itself worse or more severe."

1. The Commissioner then undertook a detailed analysis of the evidence in the context of an aggravation or an exacerbation of an underlying disease. As there seems to be no dispute about the way in which he has represented the evidence, I will summarise what he said.
2. The Commissioner dealt with Dr Jackson's evidence in the following way. He noted the doctor's primary position was that of an injury having been suffered, and quoted his comments on the aggravation scenario from a report of 27 March 2014. This was in terms that "... if there was an aggravation of his underlying condition suffered at work and/or as a result of [the worker] twisting while exiting his motor vehicle at home (which was not the way that he put it), the way that he put it was when he got out of his car he noticed significant pain. As to whether or not this can be seen as last straw events I would put it in the other context of that on the balance of probabilities, his concurrent clinical status and injury to the L5/S1 segment is directly attributable to his work place activities. I cannot possibly see any other way of interpreting the facts." (I observe that this part of Dr Jackson's report is a specific response to Dr Ruttenberg's suggestion of a disease rather than an injury.)
3. Earlier in the report Dr Jackson says that Mr Long told of increased pain, and "he developed, when he attempted to exit his vehicle, a sudden intense pain in his low back radiating down his right leg". The Commissioner said that this statement was not particularly helpful in considering the causative link between the worker's work duties and an aggravation of his underlying condition. He noted further aspects of Dr Jackson's evidence as follows.
   • In his view the disc commenced to prolapse when the pain initially came on at work and that this continued as a "rolling process" until the final insult "bang, it goes" when Mr Long attempted to get out of his car at home.
   • As to the initiation of this process, he relied upon the history given to him that on 1 March 2013 the worker was required, for a prolonged period of time, to work in a confined space.
   • His impression was that during the period 12.30pm until 5.40pm on that day, Mr Long was working substantially in a confined space.
4. The Commissioner then effectively repeated his earlier comments on Dr Jackson's views about the commencement of the prolapse and of the facts of the work involved, restating his finding that there was some occasion for Mr Long to work in a confined area but not for a "prolonged period", nor for a significant portion of the afternoon of 1 March. He said Dr Jackson failed to explain the basis of his conclusion that the disc prolapse commenced or was initiated by the work being done by the worker at the time the pain first became apparent on 1 March 2013. He noted Dr Jackson's view that the type of work being performed by the worker was capable of producing a prolapse, but said that the doctor "seems to accept that the significant aspect of the prolapse occurred as the worker attempted to get out of his car but that because pain first commenced at work 'the final result was consequential of that work'."
5. As to Dr Jackson's evidence, the Commissioner went on to say:

"A consideration of Dr Jackson's evidence shows that he accepts that the prolapse occurred as the worker attempted to get out of his car. As to this he said that this was when the 'disc goes' but he stated earlier that it 'went' when he was at home and this was when there was the sudden increase in pain. He accepted that on the history this is when the disc expanded and impinged but notes that there had been some problems before this. He agreed further that it was a reasonable inference that as the worker attempted to get out of his car the disc ruptured and impinged on the nerves as the pain suffered was ongoing after that. Finally he stated that the disc partly prolapsed at work and then 'bang, it goes' as the worker attempts to get out of his car. This appears to be a hypothesis based on the view that some physiological change occurred to the worker's disc due to the nature of his work being performed on 1 March 2013. As stated previously, I do not accept the factual basis relied upon by the doctor in this regard to be accurate. Dr Jackson accepted upon the history provided by the worker that his clinical presentation on 1 March 2013 and on 2 March 2013 up until the time that he commenced his journey home, was consistent with a non-specific low back pain or perhaps an intermittent indication of the underlying degenerative condition. There is then the history of the sudden, intense, knife like pain and sciatica when the worker gets home. Dr Jackson accepts that this describes a prolapsed disc. This description bears no resemblance to the worker's pain during the period 1 March 2013 and 2 March 2013 up until the point that he left work."

1. The Commissioner said he was not persuaded that the disc prolapse commenced at work as opined by Dr Jackson and that it continued in a manner, "which the doctor did not describe", until it dramatically prolapsed as the worker attempted to get out of the car. He expressed reservations as to whether Dr Jackson properly considered the contribution of the worker's action in attempting to get out of the car, as compared to the contribution of the work duties in regard to their significance to the happening of the prolapse.
2. Mr Dubey did not give evidence. The Commissioner noted that in a report of 23 January 2014, the doctor appeared to support the possibility of an aggravation of a pre-existing degenerative condition. The doctor's impression was that the "employment has contributed significantly to his symptomatology which started in the setting of degenerative disc disease; it is a combination of degeneration and probably as a result of his employment he became symptomatic. ... [I]t looks like an accumulative effect of his work related situation." The Commissioner said that in summary the doctor appeared to be saying that the underlying degenerative condition became symptomatic, but said the difficulty with that was that one must infer that this was based upon the history he recites in the report. That was that in March 2013 while working on a car Mr Long developed low back pain and continued to work. The following day he had pain radiating down the right leg, back of his thigh and calf, with pins and needles and numbness in similar distribution.
3. The Commissioner said that Dr Dubey was apparently not aware of the sudden and dramatic change in symptoms that occurred when the worker got home on 2 March 2013, and had not explained how the degenerative back condition progressed from low grade, generalised pain in a strap-like distribution across the lower back to the sudden knife like pain with radiation at the time of the prolapse of the disc. The Commissioner added that the reference in the report was to employment generally, not to the duties performed on 1 March 2013; Dr Dubey notes employment for a period of 3 to 4 years, and states that such employment predominantly involved bending, twisting and lifting. The Commissioner said it was difficult to tease out of Dr Dubey's comments specific support for an aggravation of the degenerative back condition on 1 or 2 March 2013 that involved a disc prolapse: "His opinion rather seems to be that it was the accumulative effect of the employment that contributed significantly to the degenerative disease itself, such opinion not being accepted by the Tribunal".
4. As to Dr Ruttenberg, the Commissioner referred to his opinion that there was a distinction between a possible aggravation of the underlying degenerative lumbar condition and the prolapse of the disc. The Commissioner also noted the following parts of the doctor's report and evidence.
   • It is more probable given the history and radiological changes, that Mr Long has simply aggravated what was already present. The changes appear more to be of natural progression of what is already present and had been made symptomatic.
   • There was a distinction between possible aggravation of the degenerative condition by performing work duties on 1 and 2 March 2013 and the incident of attempting to get out of his car at home.
   • Aspects of the worker's posture on 1 and 2 March 2013 could possibly compress the discs in his lower back and could aggravate the underlying degenerative condition, but he would have expected such aggravation to have been short lived. The performance of the work duties could have aggravated the degenerative condition but he could not say that they caused the disc prolapse.
   • As to the disc prolapse, factors were the development of the degenerative back condition, the work with the employer since 2010, the development of pain in the lower back on 1 March 2013 and the change in the nature and degree of pain during the drive home and when the worker attempted to get out of his car on 2 March 2013.
   • The final event for the disc prolapse was the worker's trip home on 2 March 2013 and attempting to get out of his car when he arrived home.
   • An estimate of the contribution of work as a cause of the disc prolapse was to the extent of 10 per cent, with a 90 per cent contribution from the overall history before 1 March 2013.
5. The Commissioner noted the use of the definite article rather than the indefinite article in the expression "the major or most significant contributing factor" as appears in par (b) of the definition of "injury". He referred to a discussion by Burke J in Harpur v State Rail Authority (NSW) [2000] NSWCC 3. As this aspect gives rise to a ground of appeal, I need to provide some detail. That discussion contained, the Commissioner said, informative comments highlighting that in "last straw" cases there is a need to look beyond the particular consequences of an event when determining causation. In Harpur, Burke J was dealing with s 9A of the Workers Compensation Act 1987 (NSW). That section qualifies s 9 which deals with foundational liability. Section 9(1) provided that a worker who has received an injury shall receive compensation from the worker's employer. Section 9A(1) provided that no compensation is payable in respect of an injury (other than a disease injury) "unless the employment concerned was a substantial contributing factor to the injury".
6. Part of a lengthy passage which the Commissioner set out from Harpur is as follows:

"66 The analysis required by s9A is as to causality not consequence. In the typical 'last straw' case the ultimate event may be relatively minor in the chain of causation but actualise quite severe incipient consequences. ...

67 The provision is concerned with the causality, not the consequence, of injury. The relevant substantial factor is to be identified in relation to the cause of the injury and not in relation to the incapacity or loss. You cannot look to the severity of the consequence of even an immediate cause as a guide to its substantiality as a cause. In the typical 'last straw' case the incident may be seen as having catastrophic consequences, as far as effects are concerned, yet have played a minor part in bringing about the injury as such. The very term 'last straw' connotes the very concept - the real causes are the other antecedent straws, this incident was just one straw too many but, nonetheless, but one straw among many_._"

1. After setting out the passage, the Commissioner commented:

"40 His Honour also addressed the meaning of 'substantial' identifying the degree or weight of contribution that such term denoted. In our legislation this has been addressed by using the term 'major or most significant' which, in my view, denotes that the relevant work contribution must be the most important or of the highest level amongst other possible causes or contributors of injury."

1. Counsel for Mr Long criticised the Commissioner's use of the word "injury", but I think it can be reasonably assumed that what was intended was a reference to a par (b) "injury". The concluding paragraphs of the Commissioner's reasons that contain the determination were the subject of close scrutiny. It is preferable to set them out in their entirety:

"41 Taking all matters into account it is arguable that the onset of pain at work on 1 March 2013 was an exacerbation of the underlying degenerative back condition. This, however, is likely in normal circumstances to have been transient and in that regard I accept the opinion of Dr Ruttenberg and note the concession by Dr Jackson that incidents of non-specific back pain may reflect underlying pathology and usually settle down. For the reasons outlined the Tribunal was not persuaded that the process of disc prolapse commenced on 1 March 2013 as an ongoing aggravation of the underlying degenerative back condition. From the evidence from the submissions and the Tribunal's own knowledge_,_ it is accepted that a frank disc prolapse can occur in a degenerative spine and in particular where a disc is bulged. It is clear from the evidence that a minor event might initiate such a prolapse. On the evidence it is clearly open to find that the disc prolapse was the end point of a progression of the degenerative back condition in which case the disease itself would be the major or most significant contributor. Also it is open to find that there was a sudden prolapse during the drive home and/or whilst the worker attempted to alight from his car, such event might classify as a separate injury or of itself be an aggravation of the degenerative back condition. In that case the travel and/or the attempt to alight from the motor vehicle could be significant contributors together with the disease itself given the minor nature of the physical activity that may have initiated that prolapse.

42 The worker's employment duties over an extended period might well have contributed to the advancement of the degenerative condition but so would hereditary factors, aging, previous incidents/insults to the affected area, and social and recreational activities. It could not be said that the short period of work with the employer would, in those circumstances, be the major or most significant contributing factor. The Tribunal is not persuaded that the disc prolapse as a manifestation of the aggravation of the underlying degenerative condition commenced in the course of the worker's employment on 1 March 2013_._ It is an equally tenable explanation if not in fact more probable that the worker's condition on 1 and 2 March 2013 was either non-specific back pain or an exacerbation of the degenerative condition, and that the prolapse of the disc on 2 March 2013 was a separate event (on the background of pre-existing degenerate back disease) occurring whilst the worker was driving home or attempting to alight from his car at home_._ On balance noting other explanations of equal or greater likelihood, the Tribunal does not accept that the disc prolapse on 2 March 2013 was as a result of an aggravation of the worker's degenerative back condition occurring in circumstances to satisfy s3 and s25(1)(b)"

1. Some grounds were abandoned. Those pursued were numbered 1, 2, 3, 5, 6, 8, 9 and 10. At the hearing of the appeal the appellant sought to add ground 16. Kmart did not agree to the amendment, but opposes it on the basis that it had no merit. The end result was that the ground was argued as part of the appeal, but with that caveat. Grounds 8, 9 and 10 were argued first and together. Grounds 1, 2, 3 and 5 were argued together, followed by grounds 6 and 16 separately.

Grounds 8(ii), 9 and 10 - "injury" by aggravation of a pre-existing disease

1. failing to direct itself that the test was whether the employment duties were a contributing factor to the disc prolapse and if so were there other contributing factors established on the evidence unrelated to the employment which displaced the employment as the major of most significant contributory factor.

1. The Tribunal erred in law ... by failing to distinguish between the major or most significant contributory factor to an aggravation of the underlying disease and the major or most contributory factor to the 'degenerative back condition' and in failing to do so the Tribunal misunderstood and misapplied the test prescribed in the second limb of the definition of 'injury' in section 3(1) of the Act.
2. The Tribunal misconstrued the test prescribed in the second limb of the definition of 'injury' in section 3(1) of the Act ... by purportedly following the law laid down in Harpur v State Rail Authority (NSW) ... to the effect that when considering whether the employment was the major or most significant factor in the aggravation or exacerbation of a disease it is appropriate to focus on the overall condition and therefore take into account the underlying disease as a contributing factor."
3. As is apparent, these grounds challenge the way in which the Commissioner approached the determination of the question. The issue is the test to be applied to a determination of whether there Mr Long had an "injury" as referred to in s 25(1) of the Act; one which is within the extended meaning of that word in par (b) of the definition in s 3(1).
4. In summary, Mr Long argues as follows.
   • The definition does not require a finding that the employment was the major or most significant contributing factor of the pre-existing injury, "and this definition excludes from consideration the pre-existing injury or disease".
   • Accordingly, in considering whether the employment was the major or most significant contributing factor to an aggravation "it would be erroneous to bring into account the pre-existing injury when deciding the major or most significant contributing factor to the aggravation". This is because if the pre-existing disease is brought into consideration, it will often, if not usually, be the major or most significant factor.
   • It follows that if the pre-existing disease is taken into account in determining the major or most significant causative factor in an aggravation or exacerbation, then any worker who suffered from a pre-existing disease would be excluded.
   • The approach outlined in Harpur v State Rail Authority (NSW) deals with a different statutory provision; the "last straw" approach to a determination of the causal relationship is an erroneous one in respect of the par (b) definition.

1. I deal firstly with the general issue of what is involved in the concept of a par (b) 'injury'. As I will show, the various 'substantives' (to borrow the word from Kitto J), used in provisions such as the definition in par (b) of s 3(1) of the Act, have different shades of meaning, and there is overlap between at least some of them. However, unless specifically dealing with one substantive, it is convenient when referring to the collection, to use 'aggravation' as a shorthand reference. Most of the provisions in other jurisdictions refer to aggravation, acceleration, exacerbation and deterioration. The par (b) definition of injury adds "recurrence".
2. Although a more recent addition to workers compensation legislation in Tasmania, 'aggravation of disease' provisions have existed in other jurisdictions for some time. It seems clear that they were introduced in response to the High Court's decision in Darling Island Stevedoring and Lighterage Co Ltd v Hussey [1959] HCA 55; (1959) 102 CLR 482. At that time the legislation under consideration provided for liability in the case of personal injury arising out of or in the course of the employment. "Personal injury" included a disease to which the employment was a contributing factor. The worker had a progressive heart disease. He collapsed and died after walking to a pick-up point for his work. Journey provisions operated to extend the journey to the employment situation. The court said that the issue related to "disease", and held that that the disease from which the worker was suffering was not contracted in the course of his employment, nor did the employment contribute to it: see in particular, Dixon CJ at 496 and Windeyer J at 518.
3. In the main, the amendments which were introduced in response (but not in Tasmania)[2] took the form of amending the definition of "injury" to include the aggravation, acceleration or deterioration of any disease, where the employment was a contributing factor to such aggravation, acceleration, exacerbation or deterioration. This 'aggravation of disease' amendment was considered by the High Court in Amalgamated Wireless (A/Asia) Ltd v Philpott [1961] HCA 31; (1962) 110 CLR 617. At 625, after referring to the amendment being made in consequence of Hussey's case, Dixon CJ, Kitto, Taylor and Windeyer JJ, at 624 observed that simply amending the definition of "injury" may be seen as curious at first sight, but confirmed that the new provision meant that if a worker was suffering from a disease however contracted, if the employment was a contributing factor to an 'aggravation', there is an injury within the meaning of the Act.
4. Plainly, the intention of the par (b) definition is to make an 'aggravation' of a pre-existing disease a compensable injury where the employment was a contributing factor to the requisite degree. In Darling Island Stevedoring and Lighterage Co Ltd v Hankinson [1967] HCA 10; (1967) 117 CLR 19, Barwick CJ at 26 pointed out that an acceleration by work, of a pre-existing disease not itself arising out of or received in the course of the employment, becomes in itself an injury within the meaning of the legislation. At 27, his Honour said, "... the injury is described in the section as the acceleration of the disease and not as the accelerated disease". [My emphasis.] The question of whether there has been an 'aggravation' is purely a question of fact based on a common sense evaluation of the whole of the evidence, and not exclusively on the medical evidence: Adelaide Stevedoring Co Ltd v Forst [1940] HCA 45; (1940) 64 CLR 538 per Rich ACJ at 563, Starke J at 565, McTiernan J at 573.
5. As to the meaning of the words in the provision, it is established that the substantives used are not to be treated as synonymous. They do have different shades of meaning and connote different consequences. At the same time, there is nothing to suggest that they are mutually exclusive and, further, that they might not overlap. I have already noted the High Court case of Federal Broom Company Pty Ltd v Semlitch in the context of setting out the Commissioner's reasons: par [24] above. He referred to the judgment of Kitto J in that case. The intermediate appellate decision is Semlitch v Federal Broom Co Pty Ltd (1964) 80 WN (NSW) 1603. Kitto J referred with approval to parts of the judgment of Moffitt J. At 1609-1610, Moffitt J said:

"Speaking very generally [the extended definition of] 'injury' is directed to a worsening of the disease, the full descriptions apparently being selected in an endeavour to be comprehensive. ...

A disease which is progressive according to its nature may, by reason of external stimuli, have its progress accelerated. Before such acceleration can be found to have caused incapacity there must be more severe or additional symptoms arising from the acceleration which have produced an incapacity which would not otherwise have existed. In this event there is an incapacity caused by an acceleration of the disease. Symptoms in the case of a progressive disease however may be only evidence of the acceleration without producing in themselves any harmful effects, in which event there may be an acceleration of the disease with no present resultant incapacity.

On the other hand a disease once contracted may be of a chronic type not subject to any progress of any susceptible progress. If external stimuli or the general nature of the disease or both, caused the disease from time to time to produce symptoms which incapacitate then in ordinary language at that time the disease is said to be worse even although the worsening may be temporary only. ...

The word 'exacerbate' involves the concept of the heightening of the effect upon an individual as where his sufferings increase. There is an exacerbation of disease with the experience of the disease by the patient is increased or intensified by an increase or intensifying of symptoms. The word is directed to the individual and the effect of the disease upon him rather than being concerned with the underlying mechanism."

1. In the High Court[1964] HCA 34; , (1964) 110 CLR 626, Windeyer J indicated at 637 that the question of whether there has been an aggravation, acceleration, exacerbation or deterioration is one of fact, and the answer depends on whether for the sufferer the consequences of the affliction have become more serious. As to the four substantives, at 639-640 his Honour said:

"The words have somewhat different meanings: one may be more apt than another to describe the circumstances of a particular case: but their several meanings are not exclusive of one another. The question each poses is, it seems to me, whether the disease has been made worse in the sense of more grave, more grievous or more serious in the effects upon the patient. ... The word 'acceleration' probably presupposes a progressive disease, one that, running its ordinary course, increases in gravity until the climax such as death or total invalidism is reached - its progress to this end result not being ordinarily susceptible of being permanently arrested, but susceptible of being hastened by external stimuli."

1. Additionally, in Darling Island Stevedoring and Lighterage Co Ltd v Hankinson (above) at 26 Barwick CJ said that the words aggravation, acceleration, exacerbation or deterioration "may overlap in their denotation but none the less they connote different consequences of work ... upon pre-existing non-employment disease". See also Asioty v Canberra Abattoir Pty Ltd [1989] HCA 40; (1989) 167 CLR 533, per Toohey J at 537. As to "acceleration", Barwick CJ, in Hankinson at 26, said the expression refers to the acceleration of the progress of the disease itself. He said he could conceive that a disease may increase the tempo of its progression and produce a result of a kind which a lesser progression may not have produced at all; it may produce a more extensive result or it may produce sooner the same result as that which without the acceleration of its progression the disease might have produced; "nor do these instances exhaust the possibilities".
2. Relevant points to be made from all of this are as follows. The substantives have different connotations but may overlap. The essence of the operation of the provision is that, irrespective of whether the existing disease pathology has been advanced or worsened, there is a relevant 'aggravation' if the symptoms and difficulties emanating from it have increased and become more serious. In either event, where the employment has contributed to the requisite degree, there is an 'injury'. The injury is the 'aggravation' of the pre-existing disease, not the aggravated disease. In the case of progressive disease, the concept of acceleration may be more readily applicable, depending on the circumstances. Whether a pre-existing disease has any causative role to play in an 'aggravation' will depend on the nature of the disease as established by the medical evidence.
3. For "the employment" to be a contributing factor under par (b) of the definition, there must an incident or state of affairs to which the worker was exposed in the performance of his duties, and to which he would not otherwise have been exposed; some event or characteristic of the work or the conditions in which it was performed: Federal Broom (above), per Kitto J (with whom Taylor and Owen JJ agreed) at 632-633, per Windeyer J at 641; Mercer v ANZ Banking Group Ltd [2000] NSWCA 138; (2000) 48 NSWLR 740, per Mason P at 745 [13]. See also University of Tasmania v Cane [1994] TASSC 73; (1994) 4 Tas R 156. Whether or not the employment is "the major or most significant" contributing factor is a matter of judgment, bearing in mind that the qualifying phrase is, as with "substantial", used in a relative sense: Mercer at 747 [27].
4. Of course, to be compensable an "injury" under the par (b) definition still has to be an injury within the meaning of s 25(1). The parties are agreed, for differently expressed reasons, that it is s 25(1)(b) which applies. There is no present cause to consider the correctness of that view, and no need to explore the reasons given. That means, of course, that in in the case of a pre-existing disease, the 'aggravation' does not have to arise out of or in the course of the employment. To apply s 25(1)(b) to an 'aggravation injury' involves significant linguistic contortions, but there seems to be no option. Section 25(1)(b) really has to be read so that the words "which is a disease", have to be substituted. Italicising the required additional words, the provision would then read, "If in any employment ... a worker suffers an injury, which is an aggravation [etc] of a pre-existing disease where the employment was the major or most significant contributing factor to that aggravation [etc], and to which the employment contributed to a substantial degree within the meaning of section 3(2A) ...". In par (b), the required degree of causal connection between an aggravation and the employment is specified in the same terms as s 3(2A). Accordingly, by the reference to s 3(2A), the reading of s 25(1)(b) becomes repetitive to that extent.
5. In support of his submissions on the present grounds, Mr Long relies on the decision in Murray v Shillingsworth [2006] NSWCA 367; (2006) 68 NSWLR 451. I am told that it was cited to the Commissioner. The case concerned the application of s 9A of the Workers Compensation Act 1987 (NSW) to s 4 of that Act. Section 9A provided that no compensation was payable in respect of an injury (other than a disease injury) unless the employment concerned was a substantial contributing factor to the injury. Section 4(a) defined "injury" as "personal injury arising out of or in the course of the employment". Section 4(b)(ii) defined "disease injury" as meaning "the aggravation, acceleration, exacerbation or deterioration in the course of employment of any disease, but only if the employment was a substantial contributing factor to the aggravation [etc]". (The section has since been amended so that employment has to be "the main contributing factor".)
6. The worker suffered a cerebral haemorrhage in the course of his employment. When distilled to the essence, there were two theories on the underlying cause of the haemorrhage. One was a benign tumour which was apt to bleed; the other was a thrombotic haemorrhage, a form of stroke in which a thrombus forms in part of the body and travels to the brain. The worker's case was that the haemorrhage had been triggered by dehydration caused by physical work in hot and trying conditions. The picture was obscured a little by a long history of smoking and of recent heavy alcohol consumption. The worker's case was put as an acceleration, aggravation or deterioration of a pre-existing atherosclerotic condition. The trial judge found in the worker's favour. The employer argued that the trial judge had drawn an untenable distinction between the application of s 9A to an injury simpliciter, and to its application to an aggravation of a pre-existing condition. The point related to the interplay between the requirement of a contributing factor in s 4, and substantial contributing factor in s 9A. It seems that the trial judge approached the matter on the basis that the substantial contributing factor had to relate to the acceleration or aggravation, not to the underlying condition.
7. At 453, Hodgson JA said:

"7 ... I think there may be cases where the question of whether the employment was a substantial contributing factor is affected by whether one considers the work occurrence as an injury simpliciter or as an aggravation of a pre-existing condition. In some cases at least, where an injury simpliciter can be considered as having been contributed to by a pre-existing condition, the employment contribution to that injury could be diluted to that extent. However, if the same event can also be regarded as an aggravation of that pre-existing condition, then the employment contribution to the aggravation may not be diluted by the pre-existing condition (although the compensation would then be strictly limited to the effect of the aggravation). This seems to have been the view taken by the primary judge, and in my opinion he was not wrong in taking that view.

8 In my opinion however, even the aggravation in this case can be seen as contributed to by dehydration resulting from the previous day's consumption of alcohol, which I would not regard as part of the respondent's pre-existing condition. The question remains whether the primary judge was in error in holding that the work-related dehydration was a substantial contributing factor. In my opinion, the primary judge was correct to disregard the long history of smoking used ... to dilute the employment contribution, because that long history was part of what gave rise to the pre-existing condition. ...".

1. Santow JA agreed with Einstein J, who wrote the principal judgment, and with the additional observations of Hodgson JA. At 464 [61], Einstein J said that there was nothing in the reasons to suggest that the trial judge misdirected himself on the test of "bridging the gap" between a contributing factor and a substantial contributing factor. "In the case of a duly proven aggravation or acceleration of a pre-existing condition, the claimant will have travelled some of the distance towards showing the employment to have been 'a substantial contributing factor to the injury'." His Honour went on to note the employer's argument to the effect that once there was a contribution to an aggravation, an "injury" was established as a juristic entity, to which s 9A applied as if there were an injury within the definition of "injury"; the statutory test was only satisfied if there had been a substantial contributing factor to a "fully blown injury".
2. At 465-466 [63]-[64], Einstein J said:

"63 These submissions are misconceived. They fail to recognise that in the circumstance concerning an integer dealt with by s 4(b)(ii) (such as an aggravation of a disease) the only compensation is for the effect of the aggravation and not for the effect of the original non-aggravated disease.

1. His Honour approached the question of construction upon the basis that the case was put as an acceleration or aggravation or deterioration of a pre-existing atherosclerotic condition in which the substantial contributing factor had to relate to the acceleration or aggravation, and not to the underlying condition. There was no error in this approach. The fact that the work-caused dehydration was sufficient to tip the balance and was on the evidence, found to satisfy the requirement that it be shown that the employment concerned was a substantial contributing factor to the injury."
2. Murray v Shillingsworth was considered by the New South Wales Court of Appeal in Cook v Midpart Pty Ltd t/as McDonalds Forster [2008] NSWCA 151, a case not referred to by either party in this case.[3] The facts are a little complex, with the claim for compensation being made against two employers. During the course of his employment with the first employer, the worker sustained injuries to his wrists and hands. Those injuries included carpel tunnel syndrome, and median nerve compression. He also suffered from degenerative osteoarthritis in the same parts of his body. He received payments of compensation, and later started with Midpart as a cleaner on a part-time basis. About 15 months later he was certified as unfit for work because of pain. He sought payments of weekly compensation from both employers.
3. An arbitrator made an award for weekly payments to be paid by Midpart as the second employer. An appeal by way of review was made to a Presidential member who revoked the award. The arbitrator had found that there had been a second injury in the course of the employment with Midpart, that being the aggravation, acceleration or exacerbation of the disease, or a further aggravation, acceleration or exacerbation of that disease. The member found that there was a gradual deterioration of the worker's condition throughout the period of his second employment, and that it was likely that at least some of the deterioration was due to the natural progression of the constitutional degenerative disease. He turned to the question of whether the employment with Midpart was a substantial contributing factor to the aggravation or exacerbation of the worker's condition, and determined that on the evidence, the employment could not be considered a weighty factor sufficient to be considered substantial.
4. On the worker's appeal, it was argued that the member fell into error by directing his attention to the total incapacity, and asking whether the employment, in part, was a substantial contributing factor to that state of incapacity. At [24], Allsop P (with whom Ipp and Bell JJA agreed), said that if that is what the member did, there would be legal error vitiating the decision, but on a proper reading of the reasons that was not the approach taken. The second relevant aspect of the argument was that the member focused on the question of whether the employment with Midpart was a substantial contributing factor to the second injury, assuming there was one, constituted by the aggravation of the worker's condition. It was submitted that this approach was wrong because it reflected a misunderstanding of the statutory provisions. Having outlined the argument, Allsop P said:

"26 The words 'aggravation, acceleration, exacerbation or deterioration of any disease' in s4(b)(ii) and the substantially identical expression in ss9A and 16(1)(b) were said not to be apt to include the worsening of the disease by its natural progression. Thus, if, as here, the worker's condition worsened after the first injury by reason of the (deteriorating) course of the condition, that is to be seen as the disease itself manifesting its natural progress, not the aggravation, acceleration, exacerbation or deterioration of the disease. The worsening of the disease captured by each of the four words chosen by Parliament does not and cannot, it was submitted, include the natural course of the disease. In effect, it was submitted that each of these words only encompasses the worsening of the disease brought about by external stimuli. Thus, it was submitted the Presidential member's assessment of the evidence by reference to the possible role of the 'constitutional factors', as he did in [48] and [49], was a legal error, because it was the taking into account of a consideration which the WC Act required not be taken into account.

1. Mr Cook submitted that this conclusion was required by the decision of this Court in Murray v Shillingsworth [2006] NSWCA 367; 68 NSWLR 451. No other authorities were referred to on this point by counsel (whether for Mr Cook or Midpart).
2. The first respondent, Midpart, submitted that the Presidential member correctly analysed the sections by reference to the worsened state of the disease and that the words 'aggravation, acceleration, exacerbation or deterioration' of the disease were apt to encompass (though, of course, not be limited to) the natural progression of the disease and that the task was to assess the substantiality (or otherwise) of employment as a contributing factor to that aggravation, acceleration, exacerbation or deterioration."
3. His Honour went on to consider the phrase, "aggravation, acceleration, exacerbation or deterioration of any disease", and referred to the judgment of Moffit J in Federal Broom Co Pty Limited v Semlitch [1964] NSWLR 511 and to the decision of the High Court; [1964] HCA 34; (1964) 110 CLR 626. Allsop P referred to the judgments in Federal Broom of McTiernan J at 629-630, and to that of Kitto J at 663-634, that passage being the one referred to in the Commissioner's reasons.
4. At par [44] Allsop P then said:

"This approach is also contrary to one (as propounded by Mr Cook) that would exclude entirely from consideration as to the content of any of these words all aspects of the progress of the disease or condition or of its symptoms that are referable to the natural progression of the disease or condition, and that are not attributable to external stimuli. Kitto J thought that 'exacerbate' concerned the effects which the disease produces in the person, that is the manifestations of the harmful or painful symptoms. This was an ordinary concept to be applied to the person in question and his condition. The relevant enquiry is whether employment was a contributing cause to that exacerbated disease. The exacerbated disease was not defined by the causal connection with external stimuli. That is, the exacerbation was not limited to the worsened state that could be attributed to external stimuli."

1. His Honour noted that in Federal Broom, Taylor and Owen JJ agreed with Kitto J. Allsop P noted that Windeyer J "likewise ... rejected the strict distinction between the disease and its essence, on the one hand, and symptoms, on the other", and said that whether there had been an aggravation, exacerbation or deterioration of a disease was a question of fact and depended "upon whether for the sufferer the consequences of his affliction have become more serious". At par [47], Allsop P said that this question was not related to what had been caused by external stimuli. His Honour continued:

"49 The argument of Mr Cook that each of the words 'aggravation', 'acceleration', 'exacerbation' and 'deterioration refers only to the additional change to the state of the disease or its symptoms and the suffering or effect they produce on the person that are caused by external stimuli and does not encompass the natural progression of the disease or its symptoms is not consistent with the approach in Federal Broom. It is also not conformable with the ordinary meaning of these words, which imports the notion of worsening, although, as counselled by Kitto J, to be understood as expressed in the four particular words used. The argument is also contrary to the terms of s9A. The terms of s9A(2)(d) and (e), in particular (d), reflect the place that the progression or state of the worker's condition may play in any analysis: see in this regard, the analysis of s9A by Mason P in Mercer.

1. Murray v Shillingsworth does not support Mr Cook's argument. Einstein J at 464-465 (with whom Hodgson JA and Santow JA agreed) was making the point that s4(b)(ii) was concerned with the aggravation of the disease and not the effect of the original non-aggravated disease. That much is clear from the terms of s4(b)(ii). The reasons of Einstein J do not, however, address the question whether the word 'aggravation', and the other words used, exclude the worsening of the condition or symptoms by the natural progression of the disease uninfluenced by external stimuli."
2. It was held that the Presidential member had not misdirected himself. The worker's appeal failed and he applied to the High Court for special leave to appeal: Cook v Midpart Pty Ltd t/as McDonalds Forster [2008] HCA Trans 402. The worker's argument was based on the apparent contradiction between what had been said in Murray v Shillingsworth. Leave was refused on the basis that the decision of the Court of Appeal did not disclose any error of principle in the application of the relevant provisions, and that the case turned upon its own facts.
3. What then is to be made of the two New South Wales Court of Appeal decisions? Care needs to be taken to put judicial statements in their proper context. The point in Murray v Shillingsworth was whether, when the "disease injury" provision in s 4(b)(ii) was engaged, the requirement in s 9A of the New South Wales Act for the employment to be a substantial contributing factor, related to the 'aggravation', or to the underlying disease. That case concerned a non-progressive condition. Cook v Midpart Pty Ltd concerned a progressive condition, and the point was a question about the meaning of aggravation in s 4(b)(ii). The issue was whether it referred to a worsening brought about only by external stimuli and did not extend to the natural progression of the disease. That is, when determining whether there was an aggravation within the meaning of the provision, no consideration was to be given to the effects of the underlying condition.
4. With respect, I agree with Allsop P when his Honour said that the judges in Murray v Shillingsworth were only making the point that s 4(b)(ii) was concerned with the aggravation of the disease and not the effect of the original non-aggravated disease. It is clear, as Allsop P pointed out, that in Murray v Shillingsworth, Einstein J did not address the particular question which arose in Cook v Midpart.
5. In my view, the decision in Cook v Midpart should be applied to the definition of "injury" in par (b) of s 3(1) of the Act. As Allsop P observed at [39]-[49], it is inconsistent with the discussions in Hussey and Federal Broom, to exclude in an appropriate case, the possible effect of natural progression when determining whether there has been an injury by 'aggravation', or more accurately, acceleration. In an appropriate case, the contribution of the employment to an aggravation will have to take into account, to the extent the evidence permits, the contribution of the natural progression of the disease to the worsening of the condition. But the worsening of the condition has to be distinguished from the end result; that is, the aggravated disease.
6. That however, is not the end of the matter. I still need to consider whether it is shown that the Commissioner did not take the correct approach to the interpretation of the definition, and did not apply the proper test.

1. The Commissioner's approach is to be discerned from a number of statements he made. In the main they appear in the passages which I have set out in pars [21] and [37] above. Although Kmart accepts that some unnecessary questions were posed and unnecessary excursions made, it submits that the Commissioner has correctly stated the exercise under the par (b) definition, and has simply not been satisfied of the required employment connection. As the reasons of an administrative decision-maker, I am conscious of the need to fairly read those reasons as a whole, and to avoid minute and fine scrutiny "with an eye keenly attuned to the perception of error": Minister for Immigration and Ethnic Affairs v Wu Shan Liang [1996] HCA 6; (1996) 185 CLR 259, per Brennan CJ, Toohey, McHugh and Gummow JJ at 272, Kirby J at 291. Bearing all of that in mind, I am satisfied that the Commissioner has not correctly identified and addressed the issues which were involved in the application of the par (b) definition of "injury". Overall, I am satisfied that the proper approach has not been taken. I will start with some general comments.
2. As I have shown, the four relevant substantives (aggravation, acceleration, exacerbation and deterioration) are not synonymous, and carry different shades of meaning, but at the same time as they might connote different things, there is nothing to suggest that they are mutually exclusive, and further, that they do not overlap. In the present case, the Commissioner considered the claim on the basis of an aggravation or exacerbation. Exacerbation was discounted on the ground that it related only to the onset of back pain at work on 1 and 2 March, "likely in normal circumstances to have been transient". In the circumstances, it might have been coupled with aggravation. On the evidence and having regard to the law as I have set it out, there does not seem to have been any reason to disregard acceleration or even deterioration. Given the nature of the pre-existing disease, the question of acceleration may be prominent. The Commissioner acknowledged that that Mr Long's employment duties over an extended period might well have contributed to the "advancement" of the condition, but did not further examine the issue. The Commissioner said that as acceleration or deterioration had not been mentioned in submissions, there was no "basis" for him to consider them.
3. The Tribunal's proceedings are not governed by pleadings. By s 49(1)(b) of the Act, proceedings are to be conducted with as little formality and technicality, and with as much expedition, as the requirements of the Act and a proper consideration of the matters to be resolved permit. The Tribunal is to decide the matter to be resolved on such evidence as is placed before it after all parties have been given a reasonable opportunity to be heard: s 57. It might be assumed that acceleration and deterioration were not expressly disavowed and it would be difficult to see how that could reasonably be done. The questions which had to be addressed, although there was no real issue about the first two, were whether Mr Long had a pre-existing disease, whether there was an 'aggravation' of that disease, and whether the employment was the major or most significant contributing factor to that 'aggravation': Federal Broom per Windeyer J at 638.
4. The evidence showed, and it is not in contention, that Mr Long had a pre-existing disease within the meaning of the par (b) definition. That disease was a degenerative, and hence progressive, process involving, primarily at least, the L5/S1 lumbar disc. On the material, I cannot see that the disease was explained by any of the doctors, but it can be inferred that it involves a process by which there is a loss of integrity of the disc. It is weakened and loses capacity to do its job. From the evidence, it is clear that the process can lead to bulging. What is precisely involved in the concept of a disc prolapse was not made clear either. It seems to have been accepted that it is a progression from a bulge to a stage in which the central part of the disc extrudes in a process of herniation. Bulging and prolapses appear to be consequences of the degenerative process.
5. The Commissioner said that it was clear from the evidence that a minor event might initiate a prolapse. He said that it was clearly open to find that the disc prolapse was the end point of the progression of a degenerative condition. It is not clear to me from the evidence whether a prolapse is or may be the natural end point of the progression of the degenerative disease; that is, the prolapse may spontaneously occur without any triggering event, however minor. It may be that it was the spontaneous occurrence to which the Commissioner was referring, but the statement is equivocal.
6. The Commissioner found that Mr Long experienced an onset of low back pain on the afternoon of 1 March 2013. That continued until the next day. Mr Long was able to work notwithstanding that pain. On any view of the evidence he suffered a sudden and dramatic worsening of his condition when he arrived home on 2 March 2013. The question was what gave rise to that worsening at that time. Mr Long needed to establish on the balance of probabilities that his employment was the major or most significant contributing factor to that worsening. That would involve consideration of the stage things had reached at relevant times and the rate of progression of the degeneration. It would involve consideration of whether the prolapse was simply the end point of a natural progression of the degeneration; that is something which would have happened at that time irrespective of what Mr Long was or had been doing. If it was not, then something has happened to bring about that result at that time. It may be that the process was hastened, with the prolapse being a result of various possible kinds: see par [49] above. It may be that external stimuli have operated on the underlying condition to bring about the prolapse.
7. The circumstances of Mr Long's employment needed to be considered and viewed comparatively, along with what activities were involved in driving the car and attempting to get out of it, the latter being an area of dispute which was not resolved as it almost inevitably should have been. I add that there is no principle that would confine an examination of "the employment" to events of 1 and 2 March. While there was an understandable focus on those days, all previous relevant work conditions might be considered in the determination of the degree of any employment contribution to an 'aggravation', as indeed was put to the Commissioner.
8. My particular reasons for the view I have about the Commissioner's approach, and which relate to his reasons given, are as follows. First, there is an aspect of the reasons which I think shows a conceptual misunderstanding and a wrong approach. It is the Commissioner's apparent view that for there to be a par (b) injury, there needed to have been an event or process of aggravation which gave rise to the prolapse, rather than viewing the prolapse itself as an 'aggravation', or worsening, of the underlying condition. Although Kitto J said in Federal Broom that the substantives are not all given their true meaning by simply asking whether the disease has been made worse, generally speaking they do refer to a worsening of the disease. That extends to an increase in symptoms or other difficulties. The substantives describe outcomes or states of affairs, not the cause of those outcomes or states or a process by which they have been brought about. They are descriptions of the injury: Hankinson at 26. Where the required causal connection is established, the outcome or effect becomes a compensable "injury". Although each expresses things in a different way, I think the Commissioner's general view is evident from the following statements set out above in the paragraphs noted:
   • "What arises from the evidence is whether the final resultant condition that resulted in incapacity, that being the disc prolapse, was the end result of an aggravation/exacerbation of the worker's disease ... ": par [21].
   • "The worker's case is that the work he was doing on 1 and 2 March 2013 involved [various] activities ... all of which placed pressure on the worker's affected back and that this led to an aggravation of his back condition that progressed to a disc prolapse": par [37].
   • "The Tribunal is not persuaded that the process of disc prolapse commenced on 1 March 2013 as an ongoing aggravation of the underlying degenerative back condition": par [37].
   • "The Tribunal is not persuaded that the disc prolapse as a manifestation of the aggravation of the underlying degenerative condition commenced in the course of the worker's employment on 1 March 2013": par [37]. [My emphasis.]
9. I am not sure I understand what is precisely meant by these various statements, but it seems to me that the practical effect of the conceptual error is that the inquiry as to causation was wrongly confined. For instance, the "last straw" concept as discussed by the Commissioner by reference to Harpur, might arise in the sense that the work conditions, superimposed on the disease, have created a situation in which the minor physical acts of driving and attempting to get out of the car have precipitated the prolapse.
10. In addition, and perhaps following on from that first aspect, it appears that the Commissioner also wrongly restricted himself to a consideration of whether there was a process of disc prolapse which commenced in the course of the employment: see the last dot point in par [76]. He seems to have been looking for some process of physiological change which had a temporal connection with the employment. This appears from the second and last of the statements set out in that paragraph. That is too restrictive an approach. The test does not require an 'aggravation' to occur, commence or conclude in the course of the employment. The question is simply whether there has been an 'aggravation' of a pre-existing disease, and whether the employment has the requisite degree of causal connection.
11. At the same time as taking that view, some of what the Commissioner said suggests that he looked to whether the employment had the required causal contribution, not to the particular 'aggravation' of the pre-existing disease, but also to the disease itself. That is, for there to be an 'aggravation' of the pre-existing disease so as to qualify, the underlying disease must in some way to also have been causally related to the employment. My observation is prompted by the Commissioner's statement that:

"The worker's employment duties over an extended period might well have contributed to the advancement of the degenerative condition but so would hereditary factors, aging, previous incidents/insults to the affected area, and social and recreational activities. It could not be said that the short period of work with the employer would_, in those circumstances,_ be the major or most significant contributing factor".

1. That approach is clearly wrong. The need for an 'aggravation' of the underlying disease, as distinct from a worsening of symptoms or manifestation of a disease, was rejected by the High Court in Federal Broom. Whether it is correct to say that disc bulges and prolapses are manifestations or effects of the disease, as distinct from the disease itself, does not matter. It is the 'aggravation;' as such to which the employment must have the required causal connection. Further, I think that it is quite unclear as to whether the Commissioner's reference to a "short period" refers to the 1½ days at work on 1 and 2 March, or the three-year period of employment with Kmart. I have previously addressed that issue.
2. Dealing with the specific grounds, ground 8(ii) is made out, except to the extent that I do not agree that the proper approach is to look for other contributing factors unrelated to the employment "which displaced the employment as the major or most significant contributory factor". Mr Long had the onus of establishing the employment was such a factor. Ground 9 is made out. The complaint in ground 10 concerns the reference to Harpur. The Commissioner said that Harpur shows the need in "last straw" cases "to look beyond the particular consequences of an event when determining causation". This may have some force in the argument to the extent that taking that point into account, in the way he appears to have done, contributed to the wrong approach to the significance of the underlying disease. But the essential point of the ground relates to the Murray v Shillingsworth point, and the ground is not maintained.
3. There is sufficient in the complaints about the Commissioner's approach in law to allow the appeal. That is sufficient to resolve the matter but, in the circumstances, I should consider the remaining grounds.

Grounds 1, 2, 3 and 5 - the Commissioner's approach to the facts

"1 The Tribunal erred in law by ignoring or failing to take into account the system of work and duties of work carried out by the Worker in determining whether the employment was a contributing factor to the injury for the purposes of section 25(1)(a) of the [WR&C] Act or the underlying disease for the purposes of section 25(1)(b) of the Act.

1. The Tribunal erred in law in failing to make findings of fact as to what was the system of work and what were the duties of work carried out by the Worker in his employment generally and specifically on the 1st and the 2nd of March 2004 for the purposes of enabling the Tribunal to determine whether the employment was:
   1. a contributing factor to an aggravation of a pre-existing disease for the purposes of establishing liability pursuant to section 25(1)(a) of the Act; and/or
   2. the pre-existing disease for the purposes of establishing liability pursuant to section 25(1)(b) of the Act.
2. The Tribunal erred in law in failing to give any or any adequate reasons as to why:
   1. the bending, lifting and twisting inherent in the system of work and duties of work carried out by the Worker were not contributory to the aggravation of the disease for the purposes of section 25(1)(a) of the Act or the disease for the purposes of section 25(1)(b) of the Act.

1. The Tribunal erred in law ... in that it failed to evaluate the three years' employment of the Worker with the Employer against any other contributing factor as it was required to do so by virtue of the second limb of the definition of 'injury' in section 3(1) of the Act and section 3(2A) of the Act for the purposes of deciding liability pursuant to section 25(1)(a) and/or section 25(1)(b) of the Act."

1. Kmart submits that, in the main, these grounds relate to errors in the fact finding process, and stresses the need for Mr Long to show error in point of law. The inadequacy of the Commissioner's reasons is specifically raised by ground 3, implicitly by ground 2, and to one degree or another found its way into the argument on the others. Kmart made detailed submissions on the issue of inadequate reasons. I should say something about the debate. The starting is the statutory requirement imposed by s 61(3) of the Act. By s 61(1), where the Tribunal makes a determination in respect of a claim for compensation referred to it, it is to make an order that gives effect to that determination. Under s 61(3), if making certain orders, the Tribunal "is to provide a statement in writing of its reasons for making the determination to which the order relates".
2. Section 63 of the Act provides that if a party to a proceeding before the Tribunal is aggrieved by a determination, order, ruling or direction in point of law, that party may appeal to the Supreme Court. The section has long been broadly interpreted as giving rise to appeals where there is an error in point of law or on a question of law. I think it can be safely assumed that s 63 extends to where the making of the determination is one based on, or involving, an error of law. This would include issues of procedural fairness. Kmart did not argue that a failure to provide adequate reasons would not amount to a failure to comply with the statutory requirement, and would not amount to an error in point of law within the meaning of s 63. That inadequacy of reasons under s 61 (3) gives rise to the right of appeal under s 63 is well established by a line of first instance decisions of which Last v Fonterra Pty Ltd [2015] TASSC 39 is a recent example.
3. A substantial part of Kmart's outline of submissions is dedicated to analysing a line of decisions of this Court that is said to apply to the Tribunal, the same duty as is required of a judicial officer giving reasons for judgment after a trial. Kmart submits that the proposition is wrong in law because the decisions wrongly assume that s 61(3) reflects the common law duty imposed on judicial officers. Kmart says it is only in very limited respects that an assertion of inadequate grounds is a valid ground of appeal, and that the standard is reflected by what gives rise to the right of appeal. It says further that the reasons required by s 61(3) are merely those required to show the Tribunal's reasons for making the determination to which the order relates. Kmart accepts that the reasons might furnish evidence of jurisdictional or legal error, although "errors claimed to arise in the fact-finding process or the exposition of that process will not amount to legal error and are not transformed into it by the statutory obligation in s 61".[4]
4. The line of authority referred to by Kmart commences with the judgment of Underwood J (as he then was) in Burgess v Umina Park Home for the Aged (1993) 2 Tas R 246 at 262. Burgess was expressly followed in Roberts Ltd v Barker [1998] TASSC 137, Barnett v Gulf Industries Pty Ltd [1999] TASSC 4, Absolom v Mary Ogilvie Homes Society [2000] TASSC 65 and Pataki v University of Tasmania [2000] TASSC 144; (2000) 9 Tas R 397. There are other decisions that, without express reference to Burgess, have equated the statutory duty with the common law judicial duty. What Underwood J actually said in Burgess was that the common law duty of a person acting judicially was "enshrined in" s 61(3). In Kmart's submission, the failure to identify the source of the Tribunal's duty and the measure of adequacy may have, on occasions, resulted in an insistence on setting out more than is required.
5. For its arguments that it is wrong to say that the Tribunal has a common law duty to give reasons, and more particularly, that it is wrong to assume that the standard of a judicial duty applies, Kmart relies on Public Service Board of New South Wales v Osmond (1996) 159 Minister for Immigration and Multicultural Affairs v Yusuf [2001] HCA 30; (2001) 206 CLR 323 and Wingfoot Australia Partners Pty Ltd v Kocak [2013] HCA 43; (2013) 252 CLR 480. CLR 656.
6. In Osmond, the High Court held that there was no general rule of the common law or principle of natural justice which required reasons to be given for administrative decisions, even those made in exercise of a statutory discretion and liable adversely to affect the rights or interests of others. In Yusuf, the court considered a statutory provision requiring the particular tribunal to prepare a written statement setting out the decision on review, the reasons for the decision, and the findings on any material questions of fact. The proceedings before the tribunal were not adversarial and there was no contradictor who joined issue on any facts alleged by an applicant. The majority of justices held that "material questions of fact" meant questions of fact that the tribunal considered material, and not questions of fact that a party or the parties considered to be material; there was no objective standard of materiality.[5]
7. In Wingfoot the High Court considered a statutory requirement for a written statement of reasons for an opinion given by a specialist medical panel. At 497-498 [43], the court (French CJ, Crennan, Bell, Gageler and Keane JJ) said that the starting point for considering the standard required under the provision was recognition that there is in Australia no free-standing common law duty to give reasons for making a statutory decision. The duty of the panel was no more and no less than the statutory duty itself; "the content of the statutory duty defines the statutory standard that a written statement of reasons must meet to fulfil it". At 498 [44], their Honours went on to say that the standard required fell to be determined as an exercise in statutory construction, and in the absence of express statutory prescription, the standard can be determined only by a process of implication. At 498 [46], two considerations were identified as of particular significance in determining by implication the standard required. The first was the nature of the function performed in forming and giving an opinion, the other was the objective, within the scheme of the legislation, of requiring a written statement of reasons for the opinion.
8. I think that as things presently stand, it must be accepted that the Tribunal has no duty at common law to provide reasons. The sole source of the obligation is the statute. In Last v Fonterra, Blow CJ acknowledged, with reference to Osmond, that the duty was a statutory one. The real question is what the difference in source means in terms of the content of the duty. In Last at par [34], his Honour said that since the Act provides for an appeal on a point of law, s 61(3) requires the provision of a statement that will disclose how the Tribunal interpreted the law and how it applied the law to the facts. The statement must be sufficient to expose any reasoning that involves, or might arguably involve, an error of law. His Honour said the provision also serves a second purpose in that it requires the Tribunal to let the parties know why they have won or lost.
9. In Burgess at 262, Underwood J said that it was well established that persons acting judicially had a duty to give adequate reasons in appropriate cases of their decisions. Two of the five cases cited by his Honour were Pettit v Dunkley [1971] 1 NSWLR 376 and Soulemezis v Dudley (Holdings) Pty Ltd (1987) 10 NSWLR 247, both well known for authoritative statements about the content of the judicial duty. I note that although Soulemezis dealt with what was then the Compensation Court of New South Wales, an appeal from that court only lay in respect of error in point of law.
10. It may well be correct to say that, in general terms, the law expects less by way of reasons from administrative decision-makers than from judicial officers: Minister for Immigration and Ethnic Affairs v Wu Shan Liang (above). However, I am not sure that advances the matter much. In the end, the standard of any statutory duty will be set by the nature of the tribunal, its statutory context and the nature of the particular matter with which it is dealing. In Pollard v RRR Corporation Pty Ltd [2009] NSWCA 110 at [56]- [66], McColl JA usefully summarised the principles relating to the judicial duty. Fundamentally, the judicial duty must be adequate for the exercise of a facility of appeal and make plain to the parties, the basis of the decision. The measure is not what is optimal, but what is necessary.
11. In considering what is the standard to be implied in the statutory duty under s 61(3), the first point of limitation is the restricted right of appeal under s 63, as observed by Blow CJ in Last. The reasons must be adequate to enable a court to ascertain whether or not an error of law has been made. The limitation has an impact on the extent to which the reasons need to deal with factual matters, but there is still the broader aspect of the exposure of how it was that the decision was reached. That aspect is underpinned by open justice and procedural fairness considerations.
12. In relation to the judicial duty, it is clear that its content depends on the nature and circumstances of the particular case; the test of adequacy is relative. There is no reason not to apply a variable standard to tribunals which deal with matters of varying nature and complexity. As to s 61(3), I think it is significant that cases in the Workers Rehabilitation and Compensation Tribunal will often be complex, conducted in an adversarial manner, and with factual issues the subject of disputed evidence involving questions of credibility and the weight to be attributed to expert evidence. The issues will be defined by the parties and the course of the hearing. That process is clearly distinguishable from an administrative "review", in which the tribunal decides for itself the material factual issues: Minister for Immigration and Multicultural Affairs v Wang (2003) 215 CLR 518 per McHugh J at 530-531 [36], per Gummow and Hayne JJ at 540 [71]. Accordingly, depending on the issues in a particular case, the standard of required reasons under s 61(3) may be relatively high.
13. Ground 2 complains of a failure to make certain findings of fact. That may be implicit in grounds 1 and 5. In general terms, a failure to state material findings of fact may be an error of law. This is because the reasons fail to serve the purposes of facilitating an appeal, and of informing the parties. At the same time, a failure to state findings of fact may conclusively show that the decision-maker has failed to take into account relevant material or has taken the wrong approach: Attorney-General v Smith no A87/1994 at p 9, [1994] TASSC 138 at [34]; Yung v Adams (1997) 80 FCR 453 at 482[6]. A review of cases in this State that deal with alleged failures to make findings of fact and suggested inadequacy of reasons in proceedings under the Act, shows that the two concepts are sometimes used interchangeably. Failures to make findings of fact are argued on the basis of inadequate reasons; that is, a failure to state findings.[7] I have little doubt that the phenomenon is more widespread. I accept that it can be safely assumed that if the findings were made, they would be set out. Conversely, if they are not set out, it might be reasonably inferred they were not made: see Yusuf per Gleeson CJ at 330 [5].
14. That leads to questions of whether the s 61(3) requirement to provide reasons gives rise to a duty to make findings of fact, and of the nature of the facts the subject of the requirement. The genesis of the notion that the s 61(3) duty creates a duty to make certain findings seems to be Australian Securities and Investment Commission v Schreuder (1994) 14 ACSR 614, [1994] TASSC 127. That was an appeal from a magistrate. Underwood J noted the judicial duty to give adequate reasons for judgment, and referred to Pettit v Dunkley per Asprey JA at 382 and Soulemezis v Dudley (Holdings) Pty Ltd per Kirby P at 259. Those judgments refer to stating or setting out the findings. His Honour said that the judicial duty required the magistrate, (among other things) to make findings with respect to the essential facts relevant to the elements of the charge. Schreuder was referred to by Zeeman J in Attorney-General v Smith (above) and applied, with the necessary modifications, in a s 61(3) appeal. That case has been cited with approval in several subsequent cases: Last v Fonterra at [36].
15. It is unnecessary to decide the existence or source of any duty to make particular findings. The better view is most likely that the true basis for a duty to make certain findings of fact arises by implication from the role of a tribunal and from the particular decision-making process itself. It may be that such a duty is another way of framing the duty to take into account all relevant material, but not a "useful" one: see the observations of McHugh, Gummow and Hayne JJ in Yusef at 347 [70]-[73]. Of course, where there are inadequate reasons as distinct from a failure to make findings, the remedy may well be different. Whatever be the true jurisprudential basis, there are authorities in this State which establish, (under the umbrella of inadequate reasons), that it is an error of law for the Tribunal to fail to make findings which are, at least, essential to the application or operation of one of the substantive provisions of the Act.
16. In Attorney-General v Smith the particular provision was s 25(1)(b); the question was whether the worker's employment had contributed to the injury to a substantial degree. His Honour said, at p 5, [18], that it was "absolutely critical that very careful findings of primary fact be made". In Gulf Industries v Barnett (1996) 6 Tas R 142 at 153, his Honour referred to the "critical" need for careful findings in relation to whether the worker had "substantially recovered" from the effects of an injury within the meaning of the section in the Act. Adjectives such as "crucial" and "essential" are used to describe the nature of the findings required to be made. See Goscombe v Cadbury Schweppes Pty Ltd [1993] TASSC 35; (1993) 3 Tas R 19 at 44, Barnett v Gulf Industries Pty Ltd [1999] TASSC 4 at [14], Wakefield v Boral Resources (Tasmania) Ltd [1999] TASSC 131 at [56][8] and Pataki v University of Tasmania [2000] TASSC 144 at [15][9]. If the true source of the duty to make such findings is s 61 (3), the essential or crucial nature of them is to be objectively assessed by reference to the operation of the substantive provision of the Act in question, and the issues framed around it. Assuming that source of the duty, I am not able to say, and it was not argued, that in light of Yusef these cases are wrongly decided, or in any event are plainly wrong.

1. To the extent that grounds 1, 2 and 5 challenge the fact-finding process as such, they must fail, as they do not involve errors of law. The propositions stated by Glass JA in Azzopardi v Tasman UEB Industries Ltd (1985) 4 NSWLR 139 at 155-157, are well established. The determination of facts by a reasoning process which is demonstrably unsound, or marred by patent error, illogicality or perversity, is not open to attack as involving an error of law. Any specific finding that is perverse, contrary to the overwhelming weight of evidence or against the weight of the evidence may involve error of fact, but does not involve an error of law.
2. However, those grounds were essentially argued on the basis that the failures alleged resulted from or demonstrated an error in the approach to the legal question of a par (b) injury. On that basis, and given what I have said about the first set of grounds, there really is no need to specifically deal with them. To the extent that they relate to, or flow from, an error in the approach to the legal question of a par (b) injury, they are made out.
3. Dealing separately with grounds 2 and 3, ground 3 is really just an aspect of ground 2. There was a great deal of general evidence before the Commissioner about Mr Long's daily working tasks and what was physically involved in them. He gave that evidence in his case. The employer called the manager operations, Mr Jones, and a former employee, Mr Wilton. Kmart also called evidence from Professor Capel, an ergonomist, who provided an assessment of the routine tasks. In addition, the Commissioner had documentary evidence about this issue. There were Mr Long's works sheets for specific jobs. There was a Kmart "Task Analysis", a document which set out all of the various physical tasks carried out by a person in Mr Long's position, with the frequency with which those tasks might be done. There was also material about biomechanics and the effect of body movements on disc prolapse.
4. It will be recalled that in par [3] of his reasons, the Commissioner noted that during the afternoon of 1 March 2013, whilst engaged in changing an engine timing belt, Mr Long became aware of low back pain. Apart from references to the nature of Mr Long's work, which were contained in the medical reports, the next reference by the Commissioner to Mr Long's duties is at par [17]. He noted Dr Jackson's reliance on a system of work involving prolonged work in a confined space, lifting and twisting; the impression generally being one of heavy work. This seems to have been in the context of the two days, 1 and 2 March. The Commissioner said:

"17 ... I do not accept that this is an accurate understanding of the system of work with a general outline provided by ergonomist Professor Caple [sic] and specific evidence by Mr Jones, an experienced mechanic, being consistent with my own experience and observations of motor mechanics at work. The work being performed by the worker on the relevant days did not involve any prolonged period working in a confined space, there may have been some lifting and twisting but there was also the opportunity to alter posture regularly during the course of performing any specific duty."

1. Of course, that was in the context of determining the first question, (a). The next reference to the nature of Mr Long's tasks, either on the two days concerned, or generally, is in par [28]. Having noted Mr Long's case on aggravation, the Commissioner said:

"... Emphasis was placed upon the asserted pressured work environment, the lack of breaks, the constant and numerous requirements to bend, twist, arch, work in confined areas and lift to establish a likelihood that such an aggravation could occur given this taxing of the worker's lower back. I repeat comments made earlier, that I do not accept that the workplace was as taxing as described by the worker or that there were few opportunities for breaks. The worker was a heavy smoker and I do not accept in those circumstances that he was able to take only three cigarette breaks per day. As also described previously, the very nature of the work allowed ongoing changes of posture and, as assessed by Professor Caple [sic], the workplace does not present as inherently unsafe."

1. In my view, more was required than very general statements to the effect that the work was not as onerous as Mr Long asserted. It is implicit in such statements that the work was onerous to a degree. On anybody's view, Mr Long's work was physical work and did involve various bodily contortions. Obviously there was dispute about the nature and extent of those. Even if the view of things most favourable to the employer were taken, the specifics of that were necessary in order to facilitate the proper assessment of what stresses may have been placed on Mr Long's vulnerable low back, and the likelihood of a disc prolapse happening as a consequence. It was common ground between the medical practitioners that bending and arching places strain on and compresses the discs in the low back. The issue was not about an unsafe workplace, nor a general level of arduousness; it was what was physically involved in terms of stresses on Mr Long's low back, particularly on 1 and 2 March.
2. In my view, specific findings as to the nature of the tasks undertaken in the employment, and to the extent the evidence permitted, the likely effects on Mr Long's spine and underlying pathology, were essential. This follows from reasons which I have given in relation to the proper approach to the ultimate question. The situation is very similar to that considered in Attorney- General v Smith (above). Such findings have not been set out; they ought to have been made and stated. Ground 2 is also made out to that extent.

Ground 6 - other potential contributory factors

"6 The Tribunal erred in law ... by taking account of other potential contributory factors which were speculatory rather than established on the evidence."

1. In my view, this ground falls into the same category in which grounds 1, 2, 3 and 5 can be placed. That is, to the extent that it asserts an error in the fact-finding process, it is not an error of law. Otherwise, it is reflective of the wrong approach which led me to uphold the grounds relating to the application of the proper test.

"16 The Tribunal erred in law in holding ... that 'the Tribunal is unable to give any appreciable weight to the significance of this incident (the stool incident) as it was not conveyed to Dr Jackson or apparently Dr Dubey'."

1. In my view leave to amend the notice of appeal by the inclusion of this ground should be refused. It cannot be characterised in any way other than an error of fact. I do not accept the position ultimately taken as to this ground, that it raises an error of law in the Wednesbury unreasonableness sense. That is, the failure to take the incident into account is something which no reasonable tribunal could have done. The Commissioner said that he could not give any "appreciable" weight to the significance of the incident. The issue remains one of fact. The ground must fail.

1. The appeal should be allowed, the determination set aside and the reference remitted. Leaving aside the question of the constitution of the Tribunal, ordinarily the order for remitter would simply be one remitting the reference for determination in accordance with the law. However, as I understand it, Mr Long's position is that question (b) might be excluded from any remitter, but that any further restriction would depend on my views about the foundational complaints for some of the grounds. Kmart's position is that if it were only ground 3 which succeeded, the remitter should be to the Chief Commissioner with the issue limited to the provision of adequate reasons; otherwise only question (c) should be remitted. In the circumstances, it is best if I hear further from the parties about this.
2. As to the constitution of the Tribunal, the governing principles of the power to remit to a difference judicial officer or a differently constituted tribunal must be used sparingly and only when it appears that it is appropriate in the interests of justice. The power to direct remittal to a differently constituted tribunal is to be exercised sparingly. Instances of grounds which provide a proper basis for such a remitter include where there have been strong findings about the credibility of a party where that will again be an issue. See Walker Corporation Pty Ltd v Sydney Harbour Foreshore Authority [2009] NSWCA 178; (2009) 168 LGERA 1 at 27-28 [119]- [121]; Kidd v Resource Management and Planning Appeal Tribunal (No 2) [2011] TASSC 46 at [9]- [18].
3. In the circumstances of this case, I think the remitter should be to a differently constituted Tribunal. At about seven points in the reasons, the Commissioner has flatly rejected the evidence of Mr Long. In only one or two instances is it possible to gain some understanding of why that might have been. Mr Long's general demeanour as a witness was not addressed. There is one instance where the evidence of Mrs Long has been flatly rejected, with no reason given. Mrs Long was not cross-examined at all.
4. The orders will be that the appeal is allowed and the determination of the Tribunal dated 1 October 2014 is set aside. Subject to further order, the reference is remitted for determination in accordance with the law by a differently constituted Tribunal.

[1] "Disease" is defined as meaning "any ailment, disorder, defect, or morbid condition, whether of sudden or gradual development".

[2] The par (b) definition of "injury" was first introduced in July 2001. Before that, "injury" was simply defined as "including a disease".

[3] Having found the case after I reserved my decision, I had the parties notified of it. I invited, and received, written submissions about its application from both parties.

[4] Kmart submits that the Tribunal's duty is akin to that of the Commonwealth Administrative Appeals Tribunal, and it will have discharged that duty "if its reasons disclose its findings of fact, the evidence on which they were based and the logical process by which it moved from those findings to the result in the case": Secretary, Department of Employment and Workplace Relations v Homewood [2006] FCA 779 per French J at[40].

[5] In Hobart City Council v Resource Management and Planning Appeal Tribunal [2007] TASSC 99, the Full Court held that Yusuf applied in the interpretation of the section of that tribunal's Act which required it to give written reasons. The provision was in similar terms to that considered in Yusuf. Section 61(3) of the Act does not specify the content of the required reasons. Kmart submits that it is less prescriptive although it did not further advance this point.

[6] In Civil Aviation Safety Authority v Central Aviation Pty Ltd [2009] FCA 49; (2009) 253 ALR 263, Perram J observed that it was the decision, not the accompanying reasons, which was the subject of an appeal. The reasons have no legal consequences in themselves but provide material from which arguments about the correctness of a decision may be crafted; the legal relevance of reasons was derivative from the decision, and it follows that the legal requirements attending the production of reasons need have no necessary connection with the legal requirements attending the decision: 271 [31] and [34].

[7] An illustration is provided by Gulf Industries Pty Ltd v Barnett (1996) 6 Tas R 142. The ground of appeal complained of a failure to determine whether a state of affairs existed within the meaning of a particular provision. Zeeman J referred to the requirement to give reasons, and held that there was a failure to make findings of fact necessary for the application of the correct legal test to be applied. That was said to be an error of law: see 150-154.

[8] Reported in [1999] TASSC 131; 9 Tas R 62, but not on this point.

[9] Reported in [2000] TASSC 144; 9 Tas R 397, but not on this point.