Martin v Australian Postal Corp

REASONS FOR JUDGMENT 1 In this appeal and cross-appeal, so called, from a decision of the Administrative Appeals Tribunal in respect of a claim made by the applicant for compensation under the Safety Rehabilitation and Compensation Act 1988, two broad issues arise. One, the subject of the appeal, is whether the Tribunal erred in law when it found the applicant's disabilities had not, "except whilst [he was] undergoing surgery on his right shoulder and recuperation from surgery", resulted in "any inability to work" (as to which see s 4(9) of the Act). The other, the subject of the cross-appeal, is whether the Tribunal erred in law when it found the applicant had suffered permanent impairment for which he was entitled to compensation under secs 24 and 27 of the Act. 2 It is necessary to outline the essential facts of the case. Mr Martin, who was born on 23 December 1940, worked at various occupations, including, for about 13 years, mining, and ultimately obtained work as a postal delivery officer with Australia Post in February 1989. In April 1990, he was delivering mail by motor bike when a dog caused him to swerve and brake, with the result that he was thrown off and landed on his right shoulder. He was able to pick up the motor bike and complete his run. He felt pain in the shoulder, and later some soreness which he put down at the time to bruising. He had never before had any problems with his shoulder. But over the next few weeks a slight nagging pain persisted, and on 7 August he saw a doctor, received cortisone injections, and took two or three days off work. Otherwise, he managed to keep working, although the symptoms became slightly more severe, requiring further cortisone injections, particularly in October 1990. Gradually, the shoulder became more sore through 1991. 3 Then, on 11 November 1991, Mr Martin had a further motor bike accident while delivering mail, this time caused by a flat tyre on a steep street. He cartwheeled as he fell, hurting particularly his right hand, as well as his right shoulder. After this accident, Mr Martin had substantially more pain in the shoulder for a few days, and then it settled down, but during 1992 it became more painful with use, particularly sorting mail and reaching up to pigeonholes when doing so. On 12 November 1992, Mr Martin left his position as a postman, but not because of his shoulder. 4 From 16 November 1992 to 25 June 1993, the applicant worked for National Panasonic (Australia) Pty Limited doing "handy person/general hand" duties and as a chauffeur for the managing director. When he resigned from that employment, he did not cite his shoulder as a reason, but a dispute involving other workers. The Tribunal did not accept that his shoulder was a factor (although it misquoted his evidence on this point), but it was proved that Mr Martin consulted a Dr Longhurst about his shoulder just over three months later, on 6 October 1993. Dr Longhurst noted, on examination, "substantially painful extension", and obtained an x-ray, which was "suggestive of calcific tendonitis". Mr Martin also saw a Dr Oliver and a Dr Hewitt. In November 1994, on referral from Dr Oliver, he saw an Associate Professor of Orthopaedic Surgery, specialising in shoulder surgery, Dr D Sonnabend, who advised that arthroscopic acromioplasty "should make [the shoulder] very much better than it is". He also advised Dr Oliver that x-rays "taken in both October and September 1994" were "diagnostic of early osteoarthritis", but a CT scan "showed the arthritic change to be minimal". He concluded: "These investigations, together with the history and examination, suggest that although Mr Martin does have early degenerative arthritis of the shoulder, his symptoms in 1994 were due to subacromial cuff impingement. Given his history, I presume he suffered an injury to the cuff with associated swelling and secondary impingement, and that the 'vicious cycle' was never broken." 5 On 11 November 1996, Mr Martin saw Associate Professor G Murrell, the Director of Orthopaedic Surgery at St George Hospital, an extremely well qualified specialist 90 per cent of whose practice is concerned with shoulders. Unfortunately, the Associate Professor's note of the history is inaccurate; and he has telescoped the two accidents into one, referring to the dog which was involved in the earlier accident, but giving the date as 1992 (after the second). He recounts that Mr Martin "was chased by a dog and fell off his bike and did several cartwheels … I do not recall whether this was a motor bike or a bicycle. It was, and is, my opinion that this type of accident could instigate the problems that he is experiencing with his left [sic] shoulder." (Mr Martin never had any problems with his left shoulder.) 6 On 23 June 1997, Mr Martin was operated on by Ass. Prof. Murrell. In the shoulder joint, there was, the doctor said, "more degeneration than one would expect in a person his age and my hypothesis is that an injury or a series of injuries caused some damage to the cartilage which then degenerated over a period of time." He could not be more precise than a "period of years". He also said: "[T]he distribution of the changes was slightly different to what one would see with what I would class as a normal degenerative arthritic joint. It looked like, to me, changes were more specific to certain areas and that would be consistent with an injury pre-disposing to some further degeneration." The doctor made it clear he did not think "just a history of heavy work [as a miner]" would account for these signs, and it was relevant that "he had no symptoms at all [before] 1990". Ass. Prof. Murrell said - and this evidence was given after it had been made clear there were not "several cartwheels" after either accident - "I think the most likely thing is that … he had an injury, several injuries, that perhaps caused some initial discomfort, but not tremendous, and perhaps damaged the cartilage and the underlying bone, and that they went on to degeneration over a period of time. In addition to that, I think he probably injured his rotator cuff and that that led to some calcification of the rotator cuff, the so-called calcific tendonitis, and that also led to a degree of impingement, so that he has the two problems, but it appears on balance the major problem is the degenerative problem in the shoulder joint." He estimated total body impairment at 10 per cent, which was unlikely to get better. 7 Assoc. Prof. Murrell gave evidence, too, that "it is not uncommon to see [calcific tendonitis] after some trauma, either a specific episode or a repetitive trauma, and it presents with pain, particularly with overhead activities." 8 In cross-examination, the doctor remained unshaken in his opinion, even after he had been asked to assume that the accidents involved less force than he had understood. He conceded, notwithstanding his own view, that there was a possibility the arthritis "could have been there anyway" and that the accidents "had only temporary effects". At the end of his evidence, he reiterated his "favoured opinion [was] that the applicant's conditions [had] been caused by trauma" - and he added "or exacerbated by it". 9 As to Mr Martin's condition following the surgery, Assoc. Prof. Murrell gave the following evidence: "Q. - Looking broadly now [at] what he can and cannot do, and ignoring for a moment any controversy in these proceedings about causation, how would you define his restrictions? A. - His restrictions is [sic] that he cannot lift heavy weights - and I would estimate anything above five kilograms he describes having difficulty with - and he cannot perform overhead activities. In other words he cannot consistently use his shoulder at or above shoulder height. Q. - So it is really repetitive or persistent movement above shoulder height that is the problem rather than occasional activity above shoulder height? A. - Yes." 10 Shortly before his operation, Mr Martin was examined by Dr R Brooks, an orthopaedic surgeon practising at Turramurra, at the request of the respondent. Dr Brooks, in his report dated 7 April 1997, diagnosed - "an impingement syndrome of the right shoulder with associated calcific tendonitis. He is also developing degenerative change in the gleno-humeral joint itself. These conditions are not post-traumatic in nature, but are of a constitutional basis." 11 Dr Brooks also expressed, in the same report, the following opinions: "Regarding fitness for work, Mr Martin is currently inhibited from many activities requiring use of the right arm, particularly in an elevated position. Most forms of active physical work would be difficult for him at this stage due to his restriction of movement and irritability of the shoulder. He would be fit for clerical or office duties or light physical work not requiring overhead lifting or reaching at shoulder height or above. If surgery is undertaken and leads to a successful outcome, it is possible that Mr Martin will have an increased work capability. It is conceivable that he could again work as a Postal Delivery officer, although it seems doubtful that he has the desire to do so. However other forms of employment involving for example driving, would presumably once again be open to him and would be appropriate to his physical abilities." He elaborated: "At present Mr Martin could carry out office based or clerical work, or light physical work such as process work done at waist height and not requiring reaching at shoulder height or above with the right arm. Driving for prolonged periods would be difficult at this stage." 12 The guarded opinion about the "possible" and "conceivable" results of surgery was justified in the event, to the extent that surgery revealed the osteoarthritis (which it could not relieve) was more significant than had been thought. Relief of the impingement therefore left Mr Martin with shoulder movements which, Dr Brooks reported after a second examination in November 1997, "remain[ed] quite restricted and irritable", so as to limit him both in lifting and in driving for more than "[o]ne to two hours … at a time". The "outcome", as Dr Brooks said in his evidence, was "not as good as was hoped." 13 In oral evidence, Dr Brooks also said Mr Martin's injuries may have "unmask[ed]" an underlying condition; and he acknowledged that "no doctor … is able to predict when an underlying asymptomatic pathology will come to light spontaneously". He said of the applicant, "it is certainly not surprising that symptoms are present, given that degree of arthritis", but he qualified this by saying that when the symptoms would appear "certainly … does involve guesswork". 14 It was in this state of the evidence that the Tribunal reached the following findings: "21. The Applicant is currently employed as a Wardsman by the Illawarra Health Service but this is a casual position. He is coping with this work and I consider any inability to engage in full-time employment is more a reflection of economic conditions in the Illawarra region than any inability on the part of the Applicant to work. In particular, having regard to the duty statements of his position at Panasonic Australia and the Postal Delivery Manual together with the evidence of Dr Brooks, plus the fact his resignations from Australia Post and Panasonic Australia were not brought about by any inability to perform the duties of his positions with those organisations, I am satisfied that at no time, save and except whilst undergoing surgery on his right shoulder and recuperation from surgery, has the Applicant illustrated any inability to work as a result of incapacity caused by his right shoulder injury. 22. Dr Murrell is the Applicant's treating orthopaedic surgeon. On 23 June 1997 he carried out an arthroscopic acromioplasty on the Applicant's right shoulder. Following that procedure Dr Murrell is of the opinion that the Applicant had two conditions affecting his right shoulder, namely a glenohumeril [scil glenohumeral] joint arthritis and an impingement syndrome associated with calcific tendonitis. 23. In the opinion of Dr Murrell the Applicant's injuries were caused by the two falls which he had from his motor cycle although he did concede in cross-examination that it was a possibility that the conditions could have been present in any event and the motor cycle accidents had a temporary effect only. Dr Murrell continued, however, that on balance he adhered to his original opinion which was that the most likely cause of the Applicant's condition was an injury or injuries which caused some initial discomfort and then went on to degeneration and that the Applicant also injured his rotator cuff which led to calcification which in turn led to a degree of impingement. 24. Dr Brooks saw the Applicant at the request of the Respondent. In his opinion the conditions suffered by the Applicant in his right shoulder are caused by degenerative change and any fall from the motor cycle would have caused a temporary exacerbation which would have resolved within one month. There is also the possibility that heavy physical work earlier in the Applicant's life, including work as a Coal Miner, was a cause of the glenohumeril [sic] arthritis. 25. Cross-examined by the Applicant's counsel, Dr Brooks conceded that whilst he could not rule out post traumatic arthritis given the Applicant's circumstances, it was more likely constitutional, as to initiate a post traumatic arthritis a fracture was required. 26. Whereas Dr Murrell has the advantage of being the treating surgeon, he appears to base his opinions on a more severe accident than that experienced by the Applicant in fact. In cross-examination he stated that he assumed that the motor cycle accident had a degree of severity and that he had a mental picture of the Applicant coming off his motor cycle and, with the force of the accident, doing several cartwheels. This of course is not the evidence before the Tribunal. 27. However, as I understand Dr Brooks' evidence whereas he opines for a constitutional condition, he does concede that coincidentally an asymptomatic condition could have been rendered symptomatic by the fall from the motor cycle. 28. I accept the Applicant's evidence that prior to the first motor cycle accident he had no symptoms in his shoulder. Dr Murrell's opinion as to a traumatic cause alone is vitiated by his over estimation of the severity of that accident. 29. Dr Brooks accepts that an asymptomatic condition could have been rendered symptomatic by the motor cycle accident and, given the Applicant's prior lack of symptoms, I consider that this scenario is more probable than not. It was also Dr Brooks' opinion, based on x-ray findings, that the condition would have become symptomatic at or around the time of the motor cycle accidents. 30. In hindsight it is impossible to say when exactly the Applicant's symptoms would have manifested themselves had the motor cycle accidents (particularly the first one) not occurred. Although I reject Dr Murrell's version of the motor cycle accident, given his opinion it is not possible to say that apart from making a previously asymptomatic condition symptomatic that the accident or accidents did not add their measure to the conditions in a material degree so as to cause an aggravation or acceleration of the said conditions. 31. The question of what compensation should be paid for the aggravation or acceleration of a non work caused disease is a vexed one. I refer to the discussion by Hill J in Casarotto v Australian Postal Commission 86 ALR 399 and in particular to two decisions cited by his Honour in that case, namely the judgment of Barwick CJ in Darling Island Stevedoring and Lighterage Co Ltd v Hankinson 117 CLR 19 at 26 and Jordan CJ in Salisbury v Australian Iron and Steel Ltd 44 SR(NSW) 157 at 161. 32. As Dr Murrell considered that the Applicant's right shoulder condition had been caused by the motor cycle accidents then obviously that cause continues. Dr Brooks at best was prepared to accept a temporary exacerbation of an existing condition. Consistent with my earlier finding that the motor cycle accidents did contribute to the Applicant's condition in a material degree, that contribution continues to date. 33. Dr Brooks, in a report dated 27 November 1997, assessed the degree of permanent impairment to the Applicant's right shoulder as 10% and this report is post operative. Dr Murrell saw the Applicant prior to giving evidence and stated that the Applicant now has less than half loss of movement in the right shoulder. This is consistent with Dr Brooks' finding. That a part of the Applicant's loss of movement in his right shoulder is attributable to a condition which was not work caused is immaterial in assessing whether any award is to be made pursuant to section 24 of the Safety, Rehabilitation and Compensation Act 1988 (the SRC Act). 34. In Comcare v Amorebieta 22 AAR 539 Jenkinson J said at p552: 'The measure of that compensation is the degree of permanent impairment which has resulted from that aggravation of the disease, and in contemplation of law the degree of impairment to which the aggravation brings the respondent's spine is caused by - "results from" - that aggravation, whatever the lesser degree of impairment was which preceded that aggravation, and whatever the extent to which events and degenerative processes preceding that aggravation contributed to cause that degree of impairment.' 35. Both specialists agree that the Applicant now suffers a degree of impairment in his right shoulder which equates to 10% on the Comcare Tables. That part of that impairment is as a result of a non work caused degenerative disease is immaterial - see Amorebieta supra. The Applicant will therefore be entitled to payments pursuant to section 24 and 27 of the SRC Act for that impairment. 36. The Applicant is not incapacitated for work because of injury. As stated, he resigned from Australia Post for reasons unconnected with his work duties and I reject his evidence that he resigned from Panasonic Australia because of any inability to carry out his duties due to shoulder pain. Presently he is coping with his current employment and that he is not more gainfully employed is due to economic factors and not incapacity to work. 37. As the Applicant's work injuries contributed to his shoulder condition he will be entitled to his medical expenses pursuant to section 16 of the SRC Act and to compensation for loss of income whilst he was undergoing the surgical procedures carried out by Dr Murrell and recuperating therefrom." On the issue of causation, the Tribunal thus came to a conclusion for which no medical specialist contended, but which each of Assoc. Prof. Murrell and Dr Brooks may have conceded to be possibly correct, that is, that the applicant's condition was the result of an aggravation or acceleration, the effect of which was continuing, of an underlying constitutional disease, a previously asymptomatic osteoarthritis. Accepting that the conclusion was open, it was reached without any reference to the obviously significant evidence of the findings at operation, without any reference to the report of Assoc. Prof. Sonnabend, and in substantial measure on the basis of a misstatement of the evidence of Assoc. Prof. Murrell (who made it quite clear his opinion did not depend on an acceptance of a more severe fall from the motor bike than that described in the evidence). But there is no appeal from the finding of an aggravation or acceleration, which is a sufficient ground for compensation, so I need not consider whether these defects in the reasons involved errors of law. 15 The appeal relates particularly to paras 21 and 36 of the reasons. Paragraph 36 seems merely to restate the earlier paragraph, while, without explanation, treating the finding "any inability to engage in full-time employment is more a reflection of economic conditions in the Illawarra region than any inability … to work" as establishing that the loss in question "is due to economic factors"! But the greater problem with this finding is that it was made without evidence. There was nothing to show the applicant was limited to part-time work as a wardsman by economic conditions in the Illawarra region, and this was not a matter on which inferences could be drawn by some sort of process of judicial notice. Nor is the Tribunal's view illuminated by its reference to the evidence of Dr Brooks and the work done by the applicant, up to four years and more before his operation, for Australia Post and National Panasonic. It was common ground that his condition had deteriorated since then, so that the operation was necessary. Dr Brooks was far from suggesting there was not any incapacity for work; although he attributed the incapacity to the inevitable progress of disease. He thought the "post-surgical response has been slow and incomplete", and he did not expect further improvement, but rather deterioration. He considered there was "doubt now" about the diagnosis of the impingement the operation was designed to alleviate, and that "most of the symptoms were due to [the unalleviated] degeneration in the glenohumeral joint". If, therefore, the applicant was unfit before the surgery, it would seem likely he remained so after it. I have earlier set out Dr Brooks's pessimistic view, even before the operation; he thought if surgery were successful, increased work capability would be possible, and ability to work again as a postman conceivable. This is not the foundation for a finding, built on "the evidence of Dr Brooks", that Mr Martin was fit for full-time work requiring the lifting of patients. 16 Nor was Mr Martin cross-examined to suggest he could and would have been working as a wardsman full-time, or in some other suitable full-time position, but for economic conditions in the Illawarra region. He gave unchallenged evidence in chief that his employment as a relief wardsman was a job "gained through the … Commonwealth Employment Service as a disadvantaged person", which involved work for about 3 months a year. That is different from ordinary employment, but it is not the same thing as a position obtained because economic difficulties limited the available openings. He was cross-examined about his doing of this work, which he said he managed, favouring his shoulder when lifting of patients was required. He also made it clear in his evidence that he would not be able to go back to mail sorting, which would involve reaching up repetitively to pigeonhole the items sorted. 17 Apart from these matters, the Tribunal's reasons make no mention, on this aspect of the case, of the evidence of the treating specialist, Assoc. Prof. Murrell. He confirmed the difficulty working overhead, and estimated a restriction in lifting weights to those not above 5 kilos. 18 It is an error of law to make a finding without evidence: see Secretary, Department of Social Security v Murphy (1998) 52 ALD 268 at 271-272. It is also an error of law for the Tribunal to fail to comply with the requirement of s 43(2) and (2B) of the Administrative Appeals Tribunal Act 1975 that it "give reasons" and that it include in its reasons "its findings on material questions of fact and a reference to the evidence or other material on which those findings were based". Paragraphs 21 and 36 of the Tribunal's reasons exhibit both of these forms of error. The defect may also be seen as a failure to consider relevant matters; or as suggesting that irrelevant matters have been considered: Repatriation Commission v O'Brien (1985) 155 CLR 422 at 446, per Brennan J (dissenting); Collins v Repatriation Commission (1980) 32 ALR 581 at 595 (Fisher J); Sullivan v Department of Transport (1978) 20 ALR 323 at 349, per Deane J; 352-353, per Fisher J; Bowman v Repatriation Commission (1981) 34 ALR 556 at 562 (Ellicott J). Whichever way it is put, there is an error of law involved when the Tribunal makes a crucial finding, its finding about capacity to work, without in any intelligible way exposing its reasoning or explaining why it has rejected substantially undisputed evidence of incapacity. The cryptic reference to the evidence of Dr Brooks, added to the baseless assertion that the small amount of work done by the applicant is "due to economic factors", underlines the point. Dr Brooks accepted significant incapacity, certainly as regards work as a postal officer; for even if surgery were successful, he was not prepared to say more than that return to the postal job would be "conceivable". In fact, both doctors agreed the result of the operation was disappointing. Even if the local economy had been shown to inhibit employment, the role of significant disabilities in placing further difficulties in the applicant's way should have been considered. It was not. 19 The essence of the requirement that the Tribunal give reasons is that its decision must be understandable. Two purposes are thereby served. The first is that a party concerned may be able to see the basis of the decision, and whether it is legally sound, or affected by some error. The second is that the discipline of the necessity to render reasons helps to keep any tribunal on the path of sound reasoning to sound conclusions. These matters have been explained in a number of decisions: Dornan v Riordan (1990) 24 FCR 564; Australian Postal Commission v Lucas (1991) 33 FCR 101 at 109; Brackenreg v Comcare Australia (1995) 56 FCR 335 at 348-351; Waldron v Comcare Australia (1995) 37 ALD 471 at 477-478; Soldatow v Australia Council (1991) 28 FCR 1; Farrelly v Minister for Immigration, Local Government and Ethnic Affairs (Hill J, unreported, 9 May 1991); Anjum v Minister for Immigration and Ethnic Affairs (1998) 52 ALD 225 at 232 et seq; Haidar v Secretary, Department of Social Security (1998) 52 ALD 255 at 260; and see the article by Hayley Katzen, Inadequacy of Reasons as a Ground of Appeal (1993) 1 AJAL 33. As to the salutary discipline of a requirement to give reasons, see the comments based on the work of the French jurist René Chapus in my own article, Administrative Law - The French Comparison (1995) 69 ALJ 977 at 981-982, where it is pointed out that the giving of reasons by a governmental administrator "acknowledges the obligation of the executive in a democracy to account for its actions, tends to improve those actions by forcing reflexion, and facilitates judicial control of the administration". The whole subject is very fully examined in the report of the review of administrative law in the United Kingdom chaired by P Neill QC, Administrative Justice Some Necessary Reforms (1988), Ch 3. 20 In my opinion, the appeal must succeed. The decision of the Tribunal will be set aside, so far as it denied that the applicant's disabilities had resulted in any incapacity for work. That question should be referred back to the Tribunal, differently constituted. As the foregoing discussion will have made clear, this ruling is supported by several grounds. I infer from the Tribunal's treatment of the material before it and its meagre reasoning that it must have taken irrelevant matters into account or failed to consider relevant matters it was bound to take into account. And it also failed to comply with the obligation that lay upon it to give sufficient reasons. The last matter, although raised in submissions, was not specified as a ground in the Notice of Appeal. However, there was no objection made to its being relied upon, no prejudice was suggested, and I would give leave to amend if formal amendment were required. 21 I turn to the cross-appeal. This is substantially based on contentions that part of the permanent impairment found is a result of degenerative disease unrelated to the employment, and that the Tribunal was bound to conclude, on its findings, that the natural progression of the applicant's disease would have overtaken any aggravation or acceleration which was held to have been caused by the work-related motor cycle accidents. As the degree of impairment assessed (10 per cent) is the minimum for compensation under s 24(7), if any part of that impairment ought not to have counted, the cross-appeal should succeed. 22 Relevantly, ss 24 and 27 provide: "24. (1) Where an injury to an employee results in a permanent impairment, Comcare is liable to pay compensation to the employee in respect of the injury. (2) For the purpose of determining whether an impairment is permanent, Comcare shall have regard to: (a) the duration of the impairment; (b) the likelihood of improvement in the employee's condition; (c) whether the employee has undertaken all reasonable rehabilitative treatment for the impairment; and (d) any other relevant matters. … (5) Comcare shall determine the degree of permanent impairment of the employee resulting from an injury under the provisions of the approved Guide. (6) The degree of permanent impairment shall be expressed as a percentage. (7) Subject to section 25 [not here relevant], where Comcare determines that the degree of permanent impairment of the employee is less than 10%, an amount of compensation is not payable to the employee under this section. … 27. (1) Where an injury to an employee results in a permanent impairment and compensation is payable in respect of the injury under section 24, Comcare is liable to pay additional compensation in accordance with this section to the employee in respect of that injury for any non-economic loss suffered by the employee as a result of that injury or impairment. …" In reading sections 24 and 27, it is necessary to bear in mind the interpretation provisions contained in s 4 of the Act. An "injury" means, among other things, "a disease suffered by an employee". A "disease" is itself defined to mean: "(a) any ailment suffered by an employee; or (b) the aggravation of any such ailment; being an ailment or an aggravation that was contributed to in a material degree by the employee's employment by the Commonwealth or a licensed corporation". An "aggravation" is defined to include "acceleration or recurrence". An "ailment" is also defined - in terms which would clearly cover the disease here in question. An "impairment" is defined to mean "the loss, the loss of the use, or the damage or malfunction, of any part of the body or of any bodily system or function or part of such system or function". There is also a definition of "permanent" which should be noted; it does not mean "to last for ever", but "likely to continue indefinitely". I note here too s 4(8), by which it is provided: "A reference in this Act to an injury suffered by an employee is, unless the contrary intention appears, a reference to an injury suffered by the employee in respect of which compensation is payable under this Act." The expression "approved Guide" is also explained in s 4 as referring to a "Guide to the Assessment of the Degree of Permanent Impairment" prepared under s 28 of the Act and approved by the Minister. 23 These provisions of the Act form part of a developed scheme for the delivery of appropriate compensation to injured workers. That scheme is the fruition of a long process of the formulation and reformulation of legislation, and of the evolution of principles through the courts for the application of the various Workers' Compensation Acts. The present Act could not be understood except in the light of its history. In my opinion, the problems which lie at the root of the cross-appeal may be elucidated by well established principles in this area of the law. In Salisbury v Australian Iron and Steel Ltd (1943) 44 SR(NSW) 157, Jordan CJ referred (at 161 et seq) to the case of a worker suffering from a progressive disease unrelated to his employment which, although it had not yet incapacitated him, would in its ordinary course eventually do so. The Chief Justice distinguished between different sorts of injuries that might be sustained by such a worker. In particular, he identified the case of an injury which operates in association with the disease itself to make it incapacitating, as it had not previously been. In such a case, he said, "the employment injury may be purely temporary in its effects. For a time it produces effects and then it ceases to produce any. So long as it produces effects, these, added to those of the disease, cause incapacity which would not otherwise exist. But when it ceases to produce effects, the stage of the disease is found to be what it would have been, and its course to continue as it would have done, if the injury had never occurred." It is clear that, at this point of his judgment, Jordan CJ is speaking of a relatively slight injury - one that is "purely temporary in its effects". But he goes on to refer to a more serious injury: "Or it may be permanent in its effects. When these are added to the effects of the disease, they cause partial incapacity which did not previously exist and would not otherwise have then come into existence, or it prematurely increases the extent of a previously existing disease incapacity. The effects of the injury do not disappear. They continue, in combination with the effects of the disease, to contribute to the premature occurrence of disability which would not then have been produced by the disease alone, and to the continuance of the incapacity so occurring. In the long run the disease alone would have caused the disability, but the injury anticipates it." In that case, "for a time at least, it is the addition of the effects of the employment injury which produces incapacity, or an increased incapacity, which would not otherwise have existed. So long as these effects continue, the fact that a non-employment injury supervenes (in the form of an accentuation of the non-employment disease), sufficient of itself to produce the incapacity or increased incapacity, does not deprive the worker of his right to continue to receive compensation." Later in the same judgment (at 164-165), Jordan CJ added: "The question in every case is, would the injured worker, had there been no supervening non-employment event, still be incapacitated by the effects of his employment injury operating solely or as a contributing factor. So long as the question should be answered in the affirmative, he is entitled to workers' compensation, and it is nothing to the point that the supervening event would itself have incapacitated him even if he had not been still disabled by his employment injury … To say that the employment injury merely accelerated the occurrence of a disability which the disease alone would inevitably have produced later on, is to say that it caused disability to occur at a time when it would not otherwise have existed but that subsequently the disease reached a stage which made it alone sufficient to produce the disability. But assuming that the worker would have been entitled to go on getting compensation if the disease had grown no worse, I cannot see how, consistently with the authorities, it can be held that the fact that the disease did get worse disentitles him to compensation. The question is, not whether the disease has caught up with the effects of the employment injury, but whether the employment injury has ceased to produce disabling effects." (Emphasis added.) 24 The same problem came under consideration in the High Court of Australia in The Darling Island Stevedoring and Lighterage Co. Limited v Hankinson (1967) 117 CLR 19. The appeal there involved a worker suffering from a spinal infection which had not disabled him but would, unless treated, in the ordinary course of events have progressed to produce a collapse of vertebrae and incapacity. He suffered at work an injury, aggravation or acceleration of his condition, resulting in total incapacity. The appellant contended, as Barwick CJ said (at 22), that "any aggravation … was of limited duration, that is to say, was limited to that period which would elapse between the date of the collapse of the vertebrae and that time at which in any event the disease of its own course would have caused incapacity." Barwick CJ pointed out (at 23) that there was "no evidence upon which the time could be established at which total incapacity would have occurred due to the progress of the infection alone". He said (at 26-27): "An acceleration by work in an employment of a pre-existing disease not itself arising out of or received in the course of the employment becomes in itself an injury within s 9 of the [Workers' Compensation Act, 1926]. … If incapacity in fact results from the acceleration, is this not enough to entitle the worker to an award in the same way or to the same extent as would be the case with any other injury? I have no doubt that it would. If the incapacity it causes ceases, the award will be for that reason terminable. But that incapacity does not cease because it is demonstrable that, without the injury, the worker would have arrived from another cause at the same state of incapacity. It seems to me nothing to the point that that other cause would have been the pre-existing disease in its own unaided progression. Where the incapacity which results from the acceleration is permanent, in my opinion, the award is not terminable because that incapacity would in any case have been the end result of the pre-existing disease." It is obvious that this reasoning could equally be applied to the Act with which I am concerned, which also contains provisions (noted above) bringing an aggravation or acceleration within the statutory concept of an injury. 25 In the same case, Taylor J (with whom, and with Owen J, Kitto J expressed agreement) said (at 31): "Whilst I agree that compensation in respect of incapacity resulting solely from the aggravation of an existing disease must be limited to the incapacity produced by the aggravation it by no means follows that the aggravation of a disease may not, itself, cause permanent incapacity. This could be said to have been the position in the present case for, if what happened on 3rd September 1964 was no more than an aggravation of the respondent's disease, it was the aggravation of that disease which directly resulted in the respondent's incapacity on and after that date. In that case, again, it is beside the point to say that if the aggravation had not occurred total incapacity or death would at some later time have resulted from the natural progress of the disease." Owen J also made it clear (at 34) that he thought it was "not to the point … to say that the respondent's pre-existing condition … would sooner or later have produced such a collapse and resultant incapacity". 26 The reasoning of Barwick CJ in Darling Island Stevedoring and Lighterage Co. Limited v Hankinson was applied unanimously by the Court of Appeal of New South Wales to a case involving the acceleration of the growth of a tumour: Zizzati Pty Limited v Ademoski (Handley, Sheller and Powell JJA, unreported, 7 April 1995). That reasoning is inconsistent with a passage in the judgment of Windeyer J in McLaughlin & Co Pty Ltd v Brinnand [1965] WCR 112 at 118 on which the cross-applicant relied. Windeyer J's dictum is cited in Darling Island Stevedoring and Lighterage Co. Limited v Hankinson at 28, and there expressly disapproved. 27 In Casarotto v Australian Postal Commission (1989) 86 ALR 399, Hill J distinguished Darling Island Stevedoring & Lighterage Co. Limited v Hankinson, for the purposes of a claim under the Compensation (Australian Government Employees) Act 1971. In that case, the employee was suffering from a degenerative spondylitic disease of the lumbar spine which, he claimed, had been aggravated by a series of work-related incidents. Each of these incidents was described as something from which the applicant had "completely recovered", or the effects of which were "short-lived", or as "fairly trivial". In the face of these findings of fact, Hill J concluded that it had been open to the Tribunal to find the employee's disability at the time of the hearing was entirely unrelated to his work. See also the comments of Heerey J in Australian Telecommunications Corporation v Davis (1991) 30 FCR 467 at 473-474. 28 In my opinion, Casarotto should not be understood as trenching upon the well accepted principle stated by Barwick CJ in Darling Island Stevedoring & Lighterage Co. Limited v Hankinson, but as an instance of minor injuries that did not produce any acceleration or significant aggravation of the underlying condition. The tribunal of fact had held such aggravation as had occurred to have been but evanescent in its effects. Casarotto was quite a different case from the present, where Mr Martin's asymptomatic condition was made symptomatic, not just for a time, but so as to continue increasingly to cause pain and disability thereafter. 29 As appears from the provisions of the Act to which I have already referred, there is a legislative direction in s 24(5), read with the definition of "approved Guide" in s 4, requiring the determination of the degree of permanent impairment of an employee resulting from an injury to be made "under the provisions of the approved Guide". That Guide, by s 28(1), must set out, inter alia, "criteria by reference to which the degree of the permanent impairment of an employee resulting from an injury shall be determined" and "methods by which the degree of permanent impairment …, as determined under those criteria, shall be expressed as a percentage". By s 28(4) the Guide is binding on the Administrative Appeals Tribunal, and an assessment "shall be made under the relevant provisions of the approved Guide." A Guide has been duly approved, containing the following provision: "If the employee's impairment is entirely attributable to a pre-existing or underlying condition, or to the natural progression of such a condition, the assessment of permanent impairment should be nil. Where it is possible to isolate the compensable effects of an injury upon a pre-existing or underlying condition the assessment of the degree of permanent impairment should reflect only the impairment due to those compensable effects." 30 There will perhaps be many cases in which it will be very difficult to determine whether and how this provision of the Guide can be applied. Whilst it may be possible (I do not say it would be in every case) to isolate the compensable effects of a further injury to the hand of a sawmiller who has previously lost a finger (whether as the result of an accident or treatment for a disease), it would be impossible to isolate those effects in, for example, many cases of previously not disabling or only mildly symptomatic diseases. Fluctuations in the severity of a constitutional condition and the similarity or identity of the effects typical of the condition, or capable of being produced by it, with those typical of an aggravation of the condition, or capable of being produced by such an aggravation, may make disentanglement of the one set of effects from the other set of effects a hopeless task. The draftsman of the approved Guide plainly recognized this by the qualification "[w]here it is possible to isolate the compensable effects of an injury". Those words should be understood as acknowledging both the wider problem to which I have referred, and the continuing validity of the analysis made by each of Jordan CJ and Barwick CJ. If there be any ambiguity, and I do not think there is, the remedial nature of the legislation would require it to be construed liberally, and not restrictively: Brennan v Comcare (1994) 50 FCR 555 at 559; Comcare v Bozicevic (1997) 144 ALR 132 at 145. 31 Whilst directing attention to the approved Guide, I should note an important limitation on its use. As Gummow J pointed out in Brennan v Comcare at 575, its function is "to set out, relevantly, the criteria by reference to which the degree of permanent impairment shall be determined and the methods by which that degree shall be expressed as a percentage"; it does not specify criteria for the determination of whether an impairment is permanent, those criteria being specified in s 24(2) of the Act. The Guide could not validly make that a permanent impairment which is not so under the Act, nor could it deny the character of a permanent impairment to that which the Act makes such an impairment. 32 In the present case, the Tribunal accepted the applicant's evidence that he had no symptoms before the first work-related accident. It considered he had an asymptomatic underlying osteoarthritis to which the work-related motorcycle accidents contributed "in a material degree", a "contribution [that] continues to date". The Tribunal expressly found that "it is impossible to say when exactly the Applicant's symptoms would have manifested themselves had the motorcycle accidents (particularly the first one) not occurred." It assessed the permanent impairment produced by the now symptomatic condition at 10%, being the figure given in evidence by both Associate Professor Murrell and Dr Brooks. 33 These findings were open to the Tribunal on the evidence. Even Dr Brooks acknowledged the possibility that "[p]eople can have an arthritic process or condition within their body that can lie dormant until the day they die …. without them noticing symptoms". So far as Mr Martin was concerned, x-rays taken in October 1993 and September 1994 were described by Associate Professor Sonnabend as "diagnostic of early osteoarthritis", and the CT scan done in November 1994 "showed the arthritic change to be minimal". In another report, the same scan was described as showing "no significant arthritis". Associate Professor Murrell gave evidence that it is "fairly rare to get glenohumeral joint arthritis in the shoulder joint and it's very rare at his age, 55." Dr Brooks conceded: "I would agree that glenohumeral arthritis is not as common in the general population as, say, hip or knee arthritis of which we see a lot and quite often there is a cause, which is why I thought of the coalmining". All this evidence would plainly support a view that emphasized the role of the aggravation or acceleration, as against the original condition. Having regard to the minimal nature of the osteoarthritic changes that had taken place by the end of 1994, which was after the aggravation had been going on for some time, the Tribunal's finding that it was "impossible to say when exactly the Applicant's symptoms would have manifested themselves [in any event]" is not only reasonable, but really inescapable. 34 In my opinion, the Tribunal's findings bring the case squarely within the principle stated by Jordan CJ and Barwick CJ. As there were no symptoms prior to the work-related injuries; those injuries aggravated or accelerated the condition so as to produce symptoms; it cannot be known when the condition itself might have produced similar symptoms in the absence of any such aggravation or acceleration; and the contribution of the aggravation or acceleration has been held (by an acceptance, in this respect, of the evidence of Associate Professor Murrell) to be still continuing, it was open to the Tribunal to find that the aggravation or acceleration which constituted the injury within the meaning of s 24 had resulted in the impairment, which was likely to continue indefinitely and therefore fell within the statutory notion of permanence. To the extent that any of these findings was not made explicitly, it was clearly implicit in what the Tribunal held. 35 But counsel for the cross-applicant argued there was error appearing in the last sentence of paragraph 33, read with paragraph 34 of the Tribunal's reasons. Counsel contended that the decision of Jenkinson J in Comcare v Amorebieta (1996) 66 FCR 83 was wrong, and that the Tribunal had embraced the error. The submission was that it was not correct to say, as Jenkinson J said in Comcare v Amorebieta at 96: "There is in my opinion no reason to think that the inclusion of the phrase 'resulting from the injury' in s 24(5) is designed to limit the operation of s 24(1), which imposes a liability to pay compensation in respect of the aggravation of the respondent's spinal disease. The measure of that compensation is the degree of permanent impairment which has resulted from that aggravation of the disease, and in contemplation of law the degree of impairment to which the aggravation brings the respondent's spine is caused by - 'results from' - that aggravation, whatever the lesser degree of impairment was which preceded that aggravation, and whatever the extent to which events and degenerative processes preceding that aggravation contributed to cause that degree of impairment." 36 I think there are two answers to counsel's contention. In the first place, the view expressed by Jenkinson J receives strong support from the terms of s 7(6) which gives the expression "resulted from" a deemed meaning apparently consistent with the meaning attributed to it by Jenkinson J. At least this much may be said, that there is no basis on which I could conclude that his Honour was clearly wrong. Unless I were able to reach that view, I should follow his Honour's decision. I may add that I do not see any inconsistency between Comcar v Amorebieta and the earlier Full Court decisions in Brennan v Comcare and Comcare v Levett (1995) 60 FCR 14, to which Jenkinson J did not find it necessary to refer. Those cases were concerned with a different problem. The second answer to counsel's contention is that the point did not really arise on the facts found by the Tribunal in the present case. The Tribunal found that Mr Martin's osteoarthritis had produced no symptoms prior to the aggravation or acceleration of it which occurred. There was no basis on which a part of the loss of movement, the pain and the disability subsequently suffered could be attributed to the underlying condition itself, as distinct from its aggravation or its accelerated state. The case fell precisely within the reasoning of Barwick CJ in Darling Island Stevedoring and Lighterage Co. Limited v Hankinson, and the remark made by the Tribunal in the last sentence of paragraph 33 was a comment on a possible difficulty which actually had no substance, having regard to the findings already made. Mr Martin's condition of disability was attributable to something other than the aggravation or acceleration only in the sense that the underlying osteoarthritis was a predisposing cause upon which the aggravation or acceleration operated. But as a cause in this sense, the underlying osteoarthritis does not deny the causal connection between the aggravation by an incident of the employment and the disability, as Jordan CJ pointed out in Salisbury v Australian Iron and Steel Ltd at 162. To borrow his striking metaphor, an aggravation "may be the catalyst which precipitates disability in a medium of disease". 37 For these reasons, the appeal should be allowed with costs, and the cross-appeal should be dismissed with costs. I certify that the preceding thirty-seven (37) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Burchett.