HRNG ADELAIDE, 6 March 1995 #DATE 27:4:1995 #ADD 24:5:1995

JUDGE1 COX J I would allow this appeal, and make the order proposed by Mullighan J, for the reasons that his Honour has given.

JUDGE2 OLSSON J This is an appeal by a worker, by leave, against an order of the Workers Compensation Appeal Tribunal confirming the determination of a Review Officer dated 10 June 1993. By that determination the Review Officer held that the worker had, on 23 May 1990, suffered a compensable disability in the nature of a closed head injury arising from his employment, which disability had incapacitated him for work for a period of two days. However, he rejected the worker's contention that a continuing psychiatric condition, which subsequently manifested itself, was causally linked to any injury sustained by the worker on the date in question.

A considerable volume of medical and lay evidence was adduced before the Review Officer and he made careful and detailed findings of fact in relation to it. Those, inter alia, focused on a considerable conflict of opinion which arose as between the various medical witnesses. This appeal concerns an issue of what inferences fairly emerged from the facts as ultimately found. It is founded upon an assertion that the Tribunal, in considering an appeal by way of rehearing from the determination of the Review Officer, erred in law, in that it approached its task by posing and applying an incorrect test in its assessment of the evidence.

I, therefore, first turn to the relevant facts.

The evidence established that the worker was of Vietnamese extraction, having been born in Saigon on 31 July 1942. He was thus almost 48 years of age at the time of the relevant accident.

He worked as a forestry engineer in Vietnam, but travelled to Australia on a refugee boat, with his present wife, in 1981. He left his then wife and two children behind in Vietnam. At the same time the worker's present wife left her husband in Vietnam, but brought her two sons with her. She was pregnant to the worker at the time.

After his arrival in Australia, the worker secured various forms of employment. He commenced employment as a process worker with a firm later known as Wingfield Heat Treaters in 1987 and continued with that firm until his accident. He was described by his employer and supervisor as being a jovial fellow, hardworking, honest and easy to get on with until about the end of 1988, when he became withdrawn, disinclined to work overtime (as he had earlier done), accident prone and requiring closer supervision.

On 23 May 1990, contrary to his usual custom, the worker did not stop work early prior to lunch to make coffee in the lunch room, but continued on with his duties. At about 12.30 pm two of his fellow workers were in the lunch room when they heard the worker "yell out". "It was not a scream but a call in a normal voice."

A fellow employee Wardale went out and found the worker lying on the ground near a quenching tank with a metal jig across his chest. The general area was described as "grotty" and it had oil on the surface of the floor. Wardale estimated the weight of the jig as being between 15-20 kilograms.

The worker's fellow employees did not observe any obvious injuries to him. They assisted him into the lunch room. He said that he hit the back of his head on the tank. He complained of discomfort in his lower back and a slight headache. Wardale drove him to a nearby clinic at Gillman, from which he was evacuated to the Queen Elizabeth Hospital by ambulance, having been examined by a doctor at the clinic.

The other employees were somewhat mystified as to how the accident had occurred and expressed themselves as having been somewhat suspicious concerning it.

The Review Officer pointed out that notes made by an ambulance officer at the time of evacuation to hospital read as follows:- "slipped in oil at work while carrying 25 kg metal bar - L.O.C. approx 30 seconds metal bar fell across pt's chest. Pt c/o pain across lower chest and has an abrasion to (R) cheek. Pt. very drowsy and vague."

According to a report from the hospital, on initial assessment at the Emergency Unit, the worker complained of severe headaches and of pain across the lower back. He appeared drowsy and unco-operative. On physical examination a symmetrical reduction of muscular power was noted in both lower extremities. It was recorded that the worker exhibited abrasions to the right face and forehead and had experienced a temporary loss of consciousness. The worker was confused and orientated in person, but not time and place. He was admitted for observation for two days and then discharged to home.

I digress to record that the evidence led on behalf of the Corporation did not concede the existence of any period of unconsciousness observed by them.

However, the hospital admission notes reveal that the case history was obtained both via an interpreter and from a "workmate". This recorded a short period of unconsciousness, in addition to which the worker had experienced some loss of memory.

What then ensued was summarised by the Tribunal in these terms:- "Thereafter Minh Hong Le noticed that he was acting in a strange manner and as a result she took him to his general practitioner Dr. Su on 28 May 1990. Dr Su took a history of the head injury at work but noted no obvious lacerations to the worker's head and that his reflexes were normal. On 6 June 1990 the worker and Minh Hong Le, who had been waiting for some time for the worker's divorce to be finalized, were married. The worker was seen again by Dr. Su and by his partner in mid June when he complained of persistent headaches and hallucinations. He was diagnosed as being psychotic and was referred to Hillcrest Hospital from where he was referred to the psychiatric ward of the Queen Elizabeth Hospital. He was admitted and observed there and treated with medication for several months before being allowed to go home. During the time that he was in hospital he continued to complain of headaches and noises in his head. He was seen to be withdrawn and behaving strangely."

A somewhat remarkable conflict arose between the medical practitioners who were called to give evidence before the Review Officer. Those who were the treating doctors, or consulted on behalf of the worker, entertained no doubt that he exhibited a significant, ongoing, disabling psychiatric condition which was causally linked to the worker's head injury. There was, however, a lack of unanimity as to how that condition ought to be categorised.

On the other hand, practitioners called or reporting on behalf of the respondent either rejected such a link or, in the case of Dr Scanlon, asserted that the worker was probably a malingerer.

In the course of his reasons, the Review Officer accepted that there had been a closed head injury and seems to have accepted that the evidence before him established that the worker did, in fact, have a significant psychiatric problem, although he did not profess to be able to resolve the conflict as to what was the correct, precise diagnosis.

In this regard the Tribunal commented:- "The Review Officer had obvious difficulties finding a particular psychiatric diagnosis. Ultimately he did not have to

do so because none of the medical evidence demonstrated a causal connection between the condition and the incident to the appropriate standard. Dr. Goldney and Dr. Van den Bos both predicated their opinions on the basis that there was nothing to suggest that the worker behaved other than normally before the incident. The Review Officer has found otherwise on the evidence presented. Moreover Dr. Goldney's opinion was also based on his observation that no other medical expert responsible for the worker's treatment found him to be simulating symptoms. That observation, although probably quite valid, does not link the condition to this incident.

Furthermore Dr. Goldney expressed the view that Ganser Syndrome can on occasions be triggered by a cerebral insult. He referred to earlier medical research that Ganser Syndrome has been triggered by cerebral typhus. He opined that there was some

cause to believe that an accident involving injury to the head could produce a similar result. He relied on the history

contained in the hospital notes that the worker had hit his head and had been unconscious for about 30 seconds to establish that there had been a cerebral insult. he said that if there had not been a head injury he would not be as confident in making the diagnosis of Ganser Syndrome.

Similarly Dr. Van den Bos, who provided a different diagnosis, that of organic mood disorder with pseudo dementia, also relied for his diagnosis on the fact that there had been a head injury. He described it as a significant closed head injury. He relied on the hospital notes which he said stated that the worker had been unconscious for some ten minutes following the incident. There was one such entry in the hospital notes but it was quite inconsistent with the notes recorded by Dr. Wayte, the ambulance officer and casualty at the Queen Elizabeth Hospital. Dr. Van den Bos described a closed head injury as a breaking of the cover of the brain itself and said that significant trauma of the brain was required to result in organic mood disorder.

There is no evidence of a significant trauma to the brain. There is certainly no evidence that the worker lost consciousness for 10 minutes. Indeed as there was nobody who witnessed the worker's fall it is not possible to know whether he was unconscious at all. The evidence that he may have been unconscious seems to have been made on the basis of his presentation immediately thereafter. However the evidence is that by the time that he saw Dr. Su five days later there was no sign of any ongoing symptoms of head injury. Thus at that stage there was nothing to indicate significant trauma to the brain. This is confirmed by Dr. North's neurological examination, the psychological testing and the neurological diagnostic tests which detected no evidence of organic brain injury of the type one would anticipate if he had damaged the brain or its covering.

It is to be noted that in his concluding remarks the Review Officer mistakenly referred to the injury as a closed head injury. That was simply an error of expression. Such an injury was not made out on the evidence and the use of that expression does not detract from the Review Officer's findings that as a consequence of the fall the worker suffered an abrasion to the right cheek and that the injury was not significant."

It seems to me that such summation accurately reflects the net impact of the acceptable medical evidence save that there was the positive note of some period of unconsciousness reported by a workmate, coupled with a degree of memory loss; and it was incorrect to suggest that the opinions of the two doctors were premised on the non existence of any prior symptoms relevant to the psychiatric condition which ultimately manifested themselves. Indeed, their evidence was, essentially, to the effect that the past history of the worker indicated that he was already a vulnerable personality and that this rendered the more explicable the development of the condition which actually ensued. As the Review Officer had properly pointed out, the opinion of Dr Van den Bos must, in any event, be considered in light of his expressed understanding that the worker was functioning, in work terms, normally prior to the incident of 23 May 1990 and that his symptoms emerged almost immediately after it. He, not surprisingly, regarded that temporal connection as very significant.

Both before the Tribunal and on this appeal counsel for the appellant relied heavily on the so-called concept of presumptive inference adverted to by Rich CJ in Adelaide Stevedoring Company Limited v Forst [1940] HCA 45; (1940-41) 64 CLR 538. (See also Watts v Rake [1960] HCA 58; (1960) 108 CLR 158 at 163, as to the onus of proof arising in this type of situation.)

However, both the Review Officer and the Tribunal were clearly troubled by the conflict of opinions arising as between the various medical experts - the more so, at least in the case of the Tribunal, in view of the evidence of the pre-accident symptoms said to have been exhibited by the worker.

Quite apart from the employer's evidence concerning the marked changed in the presentation of the worker from about the end of 1988, there was also other evidence bearing on this aspect.

Medical notes subpoenaed from general practitioners consulted by the worker in 1988 and 1989 indicated that, at that time, the worker was exhibiting symptoms of anxiety, depression and insomnia.

Moreover, case histories taken by the psychiatrists revealed that, prior to the accident, the worker had been subject to significant stressors in his personal life over a substantial period of time. I am content to accept the summation of the Tribunal in that regard. It said:- "After arriving in Australia the worker's life was not without difficulties which were recounted to the Review Officer

by his wife. The worker seemed to have no memory of any such difficulties. At some time before 1988 the worker and Minh Hong Le were estranged. During that time the worker was considering sponsoring his wife and two children to join him in Australia. When he decided, in about 1988, that he would not continue with that plan he and Minh Hong Le lived again together first at Rosewater and then at a property which they bought at Gawler. This was a market gardening property where they built a house and a number of glass houses. Minh Hong Le was responsible for the running of the market garden while the worker was at work but he also helped out whenever he could. Since his arrival in Australia and before 1990 the worker's wife said he has been ostracized by the Vietnamese community for what could be described as political reasons. In addition due to injuries sustained by one of Minh Hong Le's sons in a motor vehicle accident in September 1989 family life became difficult."

It was against the foregoing background that both the Review Officer and the Tribunal were not prepared to act upon the opinion of Dr Van den Bos that the worker was suffering from organic mood disorder with features of pseudo-dementia, secondary to a closed head injury.

The Review Officer, having made the point that the burden was on the worker to establish that his psychiatric condition and resultant incapacity arose from his employment, drew attention to the conflict of medical opinion and the prior symptoms of the worker, concluded that the worker had failed, on the balance of probability, to satisfy him that his current psychiatric symptoms were the consequences of the incident of 23 May 1990. He was of the opinion that they had no relationship to his employment or work injury.

The Tribunal, for its part, did not attempt a resolution of the conflict of medical evidence. Having rehearsed the conclusion of the Review Officer and the effect of the evidence as earlier recited it said:- "In the absence of evidence of the existence of significant head injury the factual foundation required to link Dr Van den Bos' diagnosis of organic mood disorder with psuedo dementia and Dr Goldney's diagnosis of Ganser Syndrome to the incident of 23 May 1990 was not established to the appropriate standard."

Mrs Shaw, of counsel for the worker, criticised this finding as exhibiting a fallacious approach, in common with that expressed by the Review Officer. It was her strong contention that the matter did not fall to be decided on the basis of whether or not the medical evidence, as ultimately accepted, "established a compelling relationship between" the relevant incident and the onset of the subsequent disabling psychiatric symptoms, as suggested by the Tribunal. That test was expressly rejected by the Full Court in Dahl and Anor v Grice [1981] VicRp 50; (1981) VR 513 at 522.

Rather, she said, the correct approach in law was, given that there was a reasonable body of medical evidence which indicated that it was possible that such a causal link existed, did the evidence as a totality, lead to the inference that, on the balance of probabilities, the disabling symptoms were in fact the consequence of the incident - particularly having regard to the temporal links between the two. Alternatively, she argued, an equally appropriate mode of reasoning was to consider what was the presumptive inference which the relevant sequence of events would naturally inspire in the mind of any common sense person uninstructed in pathology and then give effect to it in terms of probability, in absence of conclusive medical evidence denying that conclusion.

In my view this reasoning is undoubtedly correct. The latter formulation is that which was adopted by the High Court in Adelaide Stevedoring Company Limited v Forst (supra). The former derives from authorities such as EMI (Australia) Ltd v Bes (1970) 2 NSWR 238 at 242, Dunn v Pain; Co-operative Insurance Company Australia (Third Party) (1991) 57 SASR 133, Tubemakers of Australia Limited v Fernandez (1976) 10 ALR 303 at 304 and Dahl and Anor v Grice (supra) at 518-524.

I consider that she is correct in asserting that the Tribunal fell into error in relation to the basic legal test which ought to apply to the evidence.

Adopting the approach adverted to in the authorities to which I have referred, it seems to me that the responses given by both Dr Goldney and Dr Van den Bos, when they were pressed in cross examination concerning the pre incident symptoms noted in relation to the worker and the relevant sequence of events, were, patently, a counsel of common sense. Given that each of them accepted that the diagnosis which he espoused could have resulted from the incident, both were of the view that the sudden and dramatic escalation of symptoms immediately following it pointed strongly to the incident, operating on an already vulnerable person, as the probable cause of that situation.

To employ the language of Dr Goldney, the incident was "the pivotal point around which ... (the worker) ... has decompensated disastrously" and that, but for the incident, which on the finding of the Review Officer did result in a closed head injury, the worker "wouldn't have presented in this way".

True it was that Dr Scanlon asserted that the worker was some form of malingerer, but that opinion ran counter to both a strong body of contrary medical opinion and also the history of the worker's ultimate admission to a mental health institution as a psychotic. It was quite properly rejected as a thesis by the primary finder of fact. Dr North was not called as a witness and there is a limit to the extent to which his evidence, given from a neurosurgical point of view, can, logically, gainsay the reasoning of the psychiatrists called by the worker; and the positive finding by the Review Officer of a closed head injury based, as it was, on the content of the hospital notes.

In my opinion, had the Tribunal adopted the correct conceptual approach in this matter it would inevitably have been driven to the finding that the incident of 23 May 1990 materially contributed to the disability which followed it (cf Nader v Urban Transit Authority of New South Wales (1985) 2 NSWLR 501) and that, accordingly, should have determined that such disability was compensable.

It seems to me that both the Review Officer and the Tribunal have simply not given adequate consideration, conformably with the relevant authorities, to the compelling inference which naturally arises from the facts that:- (1) Pre-incident the worker was coping with his employment situation, at least at the standard which had prevailed since late 1988.

(2) Immediately thereafter, there was a dramatic escalation of symptoms and an incapacity for work stemming from them. He presented to Dr Su on 28 May 1990 in a confused and disorientated state and his memory was impaired. By 13 June 1990 he was found to be psychotic and hospitalised on 25 June 1990. He has exhibited significant psychiatric symptoms ever since, given some moderating effect of anti depressants and anti psychotic medication.

That scenario, viewed against the background of the psychiatric evidence, eloquently tells its own story.

I would allow the appeal and set aside the order of dismissal. I am content to join in a remitting of the application for benefits under the Act to the Review Officer to consider, in accordance with these reasons, whether the inference should be drawn from the evidence that the appellant did suffer a compensable disability in the nature of a closed head injury causing a psychiatric illness which has resulted in total incapacity for employment since 23 May 1990. I would hear the parties as to the precise order to be made.

JUDGE3 MULLIGHAN J I have had the advantage of reading the reasons for judgment of Olsson J in this appeal and I adopt his narrative of the facts.

Without question the appellant suffered an injury at work on 23rd May 1990 which is compensible and the Review Officer so found. He also found that the respondent suffers from a psychiatric disability of some severity but did not feel able to reach a conclusion as to the precise nature of the illness which produced that disability. He appears to have accepted that the illness has the symptoms of short term memory loss, persistent headaches, hallucinations, anxiety and depression and is disabling. The issue is, of course, whether there is a causal link between the injury suffered at work and the psychiatric illness whatever it might be. The Review Officer took the view that the appellant had failed to prove this link on the balance of probability, which view was upheld by the Tribunal. That conclusion is challenged on this appeal.

In my view, there was sufficient evidence to establish the link on the balance of probabilities, unless the evidence of the appellant, his wife, Dr. Goldney and Dr Van den Bos, or at least the general thrust of it, is to be rejected.

The starting point is to consider the evidence as to the nature and extent of the appellant's injury. There were no eye witnesses to the fall which resulted in the injury but evidence before the Review Officer in the form of the report of an ambulance officer who attended the appellant is that the appellant lost consciousness for approximately 30 seconds, that he had a abrasion on the right cheek, pain across the lower chest and that he was very drowsy and vague. A resident medical practitioner at the Queen Elizabeth Hospital reported that the presentation of the appellant, investigation and treatment had led to the final diagnosis of a closed head injury and that he had lost consciousness. The Hospital notes and the report of the ambulance officer were admitted into evidence, presumably as evidence of the truth of their contents and it appears that they were treated in that way. In another section of the Hospital notes, it is recorded that the appellant had been observed by workmates to have been unconscious for at least 10 minutes. However, it seems that this note was made after an examination of the appellant and as no-one had seen or heard him fall, it could not be regarded as reliable evidence of the period of unconsciousness. The appellant was ill when he gave evidence and speaks little English. It appears that he cannot remember the incident giving rise to the injury.

After the appellant was discharged from the Queen Elizabeth Hospital, he consulted Dr Su, a general medical practitioner on 28th May 1990. Dr Su reported that the appellant had sustained an injury to his head and lost consciousness which is the history given to him by the appellant's wife. The appellant presented with headaches and dizzy spells. He was confused and disorientated and sluggish in his movements. A provisional diagnosis of head injury with post-concussion syndrome was made. Dr Su did not find any haematoma or a laceration to the head and concluded that if there had been a head injury, it would not have been a serious injury. He went on to say that even a minor laceration and bump of the head would have been evident five days following the injury.

The observation of the abrasion to the head was not put to Dr Su in his evidence and it is not clear whether this last opinion was expressed in the context of a laceration. If it was, there is no suggestion in the evidence that the appellant had sustained a laceration to his head.

By 13th June 1990 he had developed hallucinations and was found to be psychotic, according to a partner of Dr Su who referred him to Hillcrest Hospital for treatment.

Evidence adduced by the respondent in the form of reports of Mr North, a neurosurgeon, and Mr Walsh, a psychologist, established that the appellant did not suffer any major head injury or lasting brain damage. True it is that Mr North, who saw the appellant on 13th May 1991 for medico-legal purposes at the request of the respondents' solicitors, categorised the head injury as "trivial". However, it must be remembered that he was not called to give evidence and his meaning of that expression was not explored, particularly against the background of the nature and extent of the head injury as reported by the ambulance officer and mentioned in the Hospital notes. Both he and Mr Walsh expressed the view that the appellant's problems lie in the area of psychiatry which is consistent with the appellant's case. It is no part of his case that he sustained a severe head injury with resultant organic brain damage which caused his symptoms.

It is to be noted that tests undertaken by Mr Walsh suggested that the appellant has a memory deficit which does not appear to be exaggerated. Mr Walsh did express his opinion in his report that he was unable to find any causal link between the appellant's psychiatric opinion and the work injury. The true significance of that opinion is at best unclear because Mr Walsh was probably speaking about an issue outside his expertise. What is of significance, is that both Mr North and Mr Walsh acknowledged that the appellant was mentally ill and that his problems were within the realm of psychiatry.

Dr Van den Bos, a psychiatrist called by the appellant, and who treated the appellant over a period of about three months, expressed the view that the head injury sustained by the appellant must have been significant in view of "the whole picture, together with the subsequent emergency of the depression (and) with cognitive impairment".

Fellow workers of the appellant did not notice any signs of trauma on the appellant's head when they attended to him after finding him on the floor. However, the appellant did complain that he had hit his head and of a headache. It was observed by the Ambulance Officer, that the appellant had an abrasion on his head and the fact that these workers did not observe any signs of trauma could not be regarded as decisive of whether the appellant had sustained a head injury.

In my view, the Review Officer was justified in concluding that the appellant had suffered a closed head injury on the evidence which I have briefly mentioned and the Tribunal erred in determining that such an injury had not been established by the evidence. The loss of consciousness is clear evidence of a closed head injury. However, the Review Officer erred in concluding that the head injury was not significant. It was obviously significant enough to cause transient unconsciousness, headache and, presumably, the condition of being very drowsy and vague. If the evidence of Dr Van den Bos is accepted, the emergence of depression and cognitive impairment establishes that the head injury was significant in that sense.

Three psychiatrists gave evidence before the Review Officer. Dr Van den Bos, Dr Goldney, who was also called by the appellant and Dr Scanlon was called by the respondent. Dr Van den Bos concluded that the appellant suffered from an organic mood disorder with features of pseudo-dementia secondary to a closed head injury. He expressed the view that it was most likely that there is a causal link between the head injury sustained by the appellant at work and this psychiatric condition.

Dr Goldney saw the appellant, for medico-legal purposes, on 28th February 1991. In his opinion it is likely that the appellant suffers from "Ganser" syndrome, which is a rare psychiatric condition and which is basically a memory disturbance as well as depression. There are difficulties in diagnosis and it is necessary to be sure that a patient presenting with the usual symptoms is not malingering but Dr Goldney felt confident that the appellant was suffering from the syndrome. Pseudo-dementia is a manifestation of the condition. According to him, whether these conditions were caused by the injury at work depended upon precisely what happened in that incident. He thought that there were other factors in the appellant's life and not just the work injury which caused the mental illness. However, he said, if it could be established that there had been a work accident which resulted in a cerebral insult, even of a fair subtle nature, that could tip the balance and cause Ganser syndrome.

So, it may be seen that there was evidence upon which the conclusion that there was a causal link between the head injury and the psychiatric condition could be made. The Review Officer did not discount the evidence of any witness on account of lack of credit and made no adverse findings against any witness. No witnesses were called before the Tribunal.

The evidence against establishing the link came from Dr Scanlon and to some extent from other witnesses. Dr Scanlon saw the appellant on 9th January 1991 for medico legal purposes at the request of the respondent's solicitors. In his opinion the appellant suffers from pseudo-dementia which raised the question of whether he had a factitious disorder, a major depressive disorder or he was malingering. He rejected the opinions expressed by Dr Van den Bos and Dr Goldney and concluded that the appellant was malingering. He acknowledged that he presented as having a pseudo-dementia but that it was to be seen as occurring in the setting of his claim for compensation and he had psychodymanic features related to his marital situation. Dr Scanlon questioned whether there was any injury at work and expressed the view that there was no link between the alleged injury and his purported symptoms. Indeed, he went on to say that from a psychiatric point of view, the appellant was capable of carrying out the duties of his former employment.

This last opinion seems to be in direct conflict with all of the other expert witnesses who did not doubt that the appellant suffers from a serious psychiatric condition, even though there was no agreement as to precisely what condition it is. Because the Review Officer found that a causal link between the head injury and the psychiatric condition had not been proved on the balance of probability, it may be accepted that he rejected the evidence of Dr Scanlon, or at least was not prepared to accept it. Had he done so, he would have made the positive finding that there was no such link.

The Review Officer was obliged to decide this critical question upon the whole of the evidence and the inferences which could reasonably be drawn from the evidence. If he was satisfied that the appellant suffered from a disabling psychiatric condition caused by the head injury, it was not essential that he decide the precise nature of that condition.

There were circumstances established by the evidence from which it could be inferred that the causal link existed. The appellant was aged 47 years at the time of the injury and was, generally speaking, in good health with a sound employment record. True it is that he had endured hardship in his past life, particularly when in Vietnam before arriving in Australia in 1980 and there had been some stresses in his marital situation but he was regarded as a good worker, of jovial disposition and easy to get on with at work, until about November 1988 when he and his wife purchased a property at Gawler. Thereafter he became more withdrawn and less jovial and required closer supervision at work according to his former employer. It appeared that he may have had financial problems in the year or so leading up to the accident.

Medical records of two medical practitioners who had treated the appellant during the period from 5th September 1985 to 5th June 1989 were admitted into evidence. They reveal, somewhat cryptically, that the appellant suffered from mild depression in 1985, periods of insomnia in 1988 and 1989 and other mild conditions commonly experienced in the community. This evidence is not capable of establishing that the appellant was otherwise than generally in good health prior to the injury at work.

Despite these matters, the evidence establishes that he was not in any way disabled or incapacitated prior to the head injury. He became seriously ill in the psychiatric sense soon after. There is no other incident proximate in time to cause or trigger the psychiatric condition. There was a respectable body of expert evidence to link the condition with the head injury. By process of reasoning, the totality of the evidence leads to the conclusion that it is more probable than not that the psychiatric condition was caused by the head injury.

Mrs Shaw submitted that the Tribunal, and presumably the Review Officer, should have first considered whether the evidence gave rise to the "presumptive inference" that the head injury caused or contributed to the psychiatric condition. If it did, it was then necessary to consider whether the medical evidence assisted one way or another to support or detract from that inference. That approach was adopted by Rich ACJ in Adelaide Stevedoring Company Ltd v Forst [1940] HCA 45; (1940) 64 CLR 538 at p563. In that case there was conflicting expert testimony as to whether a fatal heart condition was caused by exertion. The learned Judge took the view that the circumstances surrounding the death of the workman resulted from a preliminary presumption of fact in favour of the view that the work undertaken materially contributed to the cause of death. Having reached that view by a normal process of reasoning from facts found to be proved, he was able to conclude that there was nothing in the medical evidence to rebut the presumption which flows from the observed sequence of events. He went on to say, at p564: "If medical knowledge develops strong positive reasons for saying that the lay common-sense presumption is wrong, the courts, no doubt, would gladly give effect to this affirmative information. But, while science presents us with no more than a blank negation, we can only await its positive results and in the meantime act on our own intuitive inferences."

In Dunn v Pain; Co-operative Insurance Company Australia (1991) 57 SASR 133 Bollen J, with whom the other members of the Full Court agreed, adopted a similar process of reasoning in considering whether a particular medical condition was caused in a certain way.

As I understand her argument, Mrs Shaw sought to elevate this approach to a presumption of law or fact to be applied in all cases where there is a temporal connection between a disability and an injury and where causation is in issue. In my view there is no such presumption. The expression "presumptive inference" employed by Rich ACJ did no more than describe the process of reasoning from proven facts which was appropriate to the circumstances in Forst (supra). It was an approach which Bollen J also found appropriate in Dunn v Pain (supra). The process of reasoning to be adopted in any particular case will depend upon the circumstances. I have not found the approach in Forst to be appropriate in the resolution of the issues on this appeal.

In my view the evidence before the Review Officer justifies the conclusion that there is a causal link between the head injury and the psychiatric condition from which the appellant suffers. The Review Officer erred in deciding to the contrary. In my view the Tribunal erred in concluding that there was an absence of evidence of the existence of a significant head injury and consequently there was no factual formulation to link the head injury with the psychiatric condition. The correct approach was to assess and determine from all of the acceptable evidence whether the inference could safely be drawn that the causal link had been established on the balance of probabilities.

Once it is acknowledged that the appellant suffered a closed head injury sufficient to induce unconsciousness, the appellant is not malingering. The head injury is then a known cause or a contributing cause of the psychiatric condition from which the appellant is suffering, whatever its precise nature may be. If there is no other likely cause, the necessary causal link between the injury at work and the disabling condition is established on the balance of probability. Such a conclusion is reached by merely drawing inferences from established facts.

This is an appeal pursuant to s100 of the Worker's Rehabilitation and Compensation Act 1986 and by reason of s100(3) is limited to a question of law. The Tribunal and the Review Officer wrongly decided that inferences could not be drawn from the proven facts so as to conclude that the causal link between the work injury and the psychiatric condition had been established. Whether an inference can be drawn from proven facts is a question of law: Hope v The Council of the City of Bathhurst [1980] HCA 16; (1980) 144 CLR 1 at pp7-8 and Australian Broadcasting Tribunal v Bond and Ors [1990] HCA 33; (1990) 170 CLR 321 at p355. In my view, the inference could have been drawn and the decision to the contrary was an error of law.

I would allow the appeal and remit the application for benefits under the Act to the Review Officer to consider, in accordance with these reasons, whether the inference should be drawn from the evidence that the appellant did suffer a compensable disability in the nature of a closed head injury causing a psychiatric illness which has resulted in total incapacity for employment since 23rd May 1990. I would hear the parties as to the precise order to be made.