FEDERAL COURT OF AUSTRALIA Wheeldon v Repatriation Commission [1999] FCA 1397 VETERANS' AFFAIRS – Veterans' Entitlements Act 1986 (Cth) ("the Act") – claim for pension on the basis that disease and subsequent death war-caused – whether the Administrative Appeals Tribunal ("the Tribunal") erred in finding no reasonable hypothesis linking the veteran's cancer of the oesophagus and his exposure to DDT during operational service – whether the Tribunal was entitled to conclude on the evidence before it that the hypothesis was not reasonable – manner is which Tribunal has regard to expert evidence Veterans' Entitlements Act 1986 (Cth), ss 13, 120, 120A, 120B Byrnes v Repatriation Commission (1993) 177 CLR 564 Repatriation Commission v Whetton (1991) 31 FCR 513 East v Repatriation Commission (1987) 16 FCR 517 Repatriation Commission v Bey (1997) 79 FCR 364 Repatriation Commission v Owens (1996) 70 ALJR 904 Bushell v Repatriation Commission (1992) 175 CLR 408 Critch v Repatriation Commission (1996) 43 ALD 574 LILLIAN ISOBEL WHEELDON v REPATRIATION COMMISSION NG 952 of 1998 BURCHETT, BRANSON and RD NICHOLSON JJ SYDNEY 12 OCTOBER 1999 IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NG 952 of 1998 ON APPEAL FROM A JUDGE OF THE FEDERAL COURT OF AUSTRALIA BETWEEN: LILLIAN ISOBEL WHEELDON Appellant AND: REPATRIATION COMMISSION Respondent JUDGE: BURCHETT, Branson AND RD NICHOLSON JJ DATE OF ORDER: 12 OCTOBER 1999 WHERE MADE: SYDNEY THE COURT ORDERS THAT: The appeal be dismissed. Note: Settlement and entry of orders is dealt with in Order 36 of the Federal Court Rules. IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NG 952 of 1998 ON APPEAL FROM A JUDGE OF THE FEDERAL COURT OF AUSTRALIA BETWEEN: LILLIAN ISOBEL WHEELDON Appellant AND: REPATRIATION COMMISSION Respondent JUDGE: BURCHETT, BRANSON AND R D NICHOLSON JJ DATE: 12 OCTOBER 1999 PLACE: SYDNEY REASONS FOR JUDGMENT BURCHETT J 1 Alfred George Wheeldon saw operational service during the Second World War in Papua New Guinea. As a sergeant in the Second Australian Independent Farm Platoon, he was exposed, according to uncontradicted evidence, to the insecticide DDT "on many occasions", being the non-commissioned officer in charge of spraying operations. DDT is perhaps the best known of the organochlorine compounds, a class of insecticides banned from general use in many countries (including Australia), since the 1970s, because of problems both of toxicity and of persistence. On 18 January 1994, Mr Wheeldon died of an adenocarcinoma of the oesophagus. The question in this appeal, brought by his widow, is whether the judge at first instance was right to affirm the decision of the Administrative Appeals Tribunal that the material before it did not raise a reasonable hypothesis connecting Mr Wheeldon's death with the circumstances of his service – in particular, his substantial exposure to DDT. 2 The claim that the material did raise a reasonable hypothesis of a link between the fatal cancer and the DDT was first advanced on the widow's behalf by Dr J Grygiel, Associate Professor of Medicine and Senior Staff Oncologist at St Vincent's Hospital where the deceased received radiotherapy. He wrote to Mrs Wheeldon, as follows: "In relation to your enquiry about the extensive use of DDT over a long period to spray vegetable crops grown for Army use as a possible link to his development of oesophageal cancer, I think that this is a reasonable theory to explore, since it is well known that DDT exposure in the long term does have some influence on the relative risk of developing cancer and has been documented in cases of pancreatic cancer, breast cancer and other tumours. The case for the association between DDT and pancreatic cancer has only really come to light in the last couple of years with the majority of publications associating pancreatic cancer causation to DDT appearing in 1992. It is clear from animal experimentation that DDT can cause point mutations and other changes to chromosomes which may lead to the development of cancer and it is reasonable to assume that there are some sections of the population, of which your husband may number, that needed only the exposure to DDT to go on to develop oesophageal cancer. It must be remembered that the associations of cancer causation between cigarette smoke took quite some time to be accepted by the community in general and it may well be that the role of DDT in the causation of cancer is yet to be fully appreciated. While I do not think that there is sufficient direct evidence to implicate DDT in the case of your husband's development of oesophageal cancer, it still remains a fact that DDT is a recognised carcinogen and that DDT contaminated vegetables grown for the Army may have played a role in the causation of his disease and therefore his untimely death." In a subsequent letter, he referred to "the evidence accruing of the emergence of an increased incidence of various cancers that would appear to be related to exposure to DDT in the distant past". 3 But the Tribunal brushed this aside with the comment: "Dr Grygiel does not go further and state why he thought DDT may have played a role in the causation of the Deceased's disease." Perhaps the Tribunal – which began its reasons with a complaint that it was "unrealistic to expect a layman to have a full and complete understanding of the science discussed by the expert witnesses" – simply misunderstood the language of the medical scientist. For Dr Grygiel had certainly made his reasons clear: that DDT had "some influence" on cancer risk was, he said, "well known"; it had "been documented" for such different cancers as pancreatic cancer and breast cancer, and for "other tumours"; in the case of pancreatic cancer, the evidence had "only really come to light" very recently (suggesting the fact that similar evidence had not yet come to light for oesophageal cancer was not significant – a point he also illustrated by reference to the long delayed implication of cigarettes in the development of cancers); a theoretical basis existed in that DDT had been shown experimentally (not, it may be noted, epidemiologically) to "cause point mutations [that is, biochemical abnormalities at some points in the base sequence of the DNA of the chromosome – those interested will find scientific definitions in The New Shorter Oxford English Dictionary (1993 ed.), and in Henderson's Dictionary of Biological Terms (11th ed., 1995)] and other changes to chromosomes which may lead to the development of cancer"; and, given these propositions, he thought it "reasonable to assume that there are some sections of the population [of whom Mr Wheeldon may have been one] that needed only the exposure to DDT to go on to develop oesophageal cancer". 4 When propositions of this kind are put forward by a medical scientist, accredited by a University as an Associate Professor of Medicine and by a major hospital as a Senior Staff Oncologist, the facts not being in dispute, I have great difficulty in seeing how – except in the most unusual circumstances – the hypothesis he proffers can be dismissed by a lay tribunal as "not reasonable". In Bushell v Repatriation Commission (1992) 175 CLR 408 at 414-415, Mason CJ, Deane and McHugh JJ, after pointing out that a hypothesis cannot be reasonable if it is contrary to the laws of nature or "obviously fanciful, impossible, incredible or not tenable or too remote or too tenuous" (emphasis supplied), continued: "But leaving aside cases of those kinds, the case must be rare where it can be said that a hypothesis, based on the raised facts, is unreasonable when it is put forward by a medical practitioner who is eminent in the relevant field of knowledge. Conflict with other medical opinions is not sufficient to reject a hypothesis as unreasonable. As we have earlier pointed out, it is not the function of s. 120(3) to require the Commission to choose between competing hypotheses or to determine whether one medical or scientific opinion is to be preferred to another. This does not mean, however, that in performing its functions under s. 120(3) the Commission cannot have regard to the medical or scientific material which is opposed to the material which supports the veteran's claim. Indeed, the Commission is bound to have regard to the opposing material for the purpose of examining the validity of the reasoning which supports the claim that there is a connexion between the incapacity or death and the service of a veteran. But it is vital that the Commission keep in mind that a hypothesis may still be reasonable although it is unproved and opposed to the weight of informed opinion." In the same case, Brennan J said (at 430): "It would be an exceptional case in which it would be right for the A.A.T., forming its own view of competing medical theories, to hold an hypothesis of connexion favouring entitlement to be unreasonable, when the hypothesis is supported by 'a responsible medical practitioner, speaking within the ambit of his expertise'." 5 But although the Tribunal rejected, virtually out of hand, the broad hypothesis put forward by Dr Grygiel, it did discuss, and then reject, what it took to be a narrower hypothesis put forward by another expert, Dr P McCullagh. Dr McCullagh is a Senior Fellow (since 1974) in the Division of Clinical Sciences at the John Curtin School of Medical Research, Australian National University, whose research interests have included the immune system, tumours and experimental embryology. He has a doctorate in medicine from Melbourne University and is a Member of the Royal College of Physicians, London. Dr McCullagh noted there had been no studies, either confirming or denying, a link between DDT and oesophageal cancer, in particular, oesophageal adenocarcinoma, a fairly rare condition. But very recent studies had raised a likelihood that DDT was linked to pancreatic cancer and breast cancer, and laboratory experiments (not only epidemiological evidence) had linked it to cancers in several animals. An epidemiological study had also suggested an association with stomach cancer. Dr McCullagh pointed to the common embryological origin of the pancreas and the particular tissue of the oesophagus which is involved in an adenocarcinoma. Thus he added to the broad hypothesis of Dr Grygiel – which he said "many people have proposed", that is, many scientists – a sub-hypothesis proposing a particular reason to consider a link in the case of an adenocarcinoma of the oesophagus. He said it was "conventional" to consider that "cells which have a common origin embryologically are likely to share common risk factors". He said the evidence about pancreatic carcinoma in association with DDT "suggests very clearly that one should be looking at cognate cell types as candidates for being affected by DDT and one of those would certainly be [the cells involved in an adenocarcinoma of the oesophagus]". 6 Against this hypothesis, the respondent relied on the evidence of Prof. J. Levi, Director of the Department of Clinical Oncology at the Royal North Shore Hospital. He said that "to extrapolate [from a finding about pancreatic cancer] to any other carcinoma … is fanciful". His evidence was summed up in the statement: "You see the fact that an agent is carcinogenic for one tumour type has no implication at all to a completely unrelated tumour type." He referred repeatedly to the lack of evidence associating oesophageal cancer with DDT. 7 So the case came down to this. An eminent clinician and an eminent medical research scientist considered there was an available hypothesis to support the appellant's contentions; while an eminent clinician on the other side thought there was not. The plain answer to a conflict of that kind, according to Bushell, is that a difference of medical or scientific opinion does not destroy a hypothesis. As was said in a passage I have quoted, "[c]onflict with other medical opinions is not sufficient to reject a hypothesis as unreasonable". Indeed, in Byrnes v Repatriation Commission (1993) 177 CLR 564 at 569, Mason CJ, Gaudron and McHugh JJ emphasized that "it is not decisive that a medical opinion that supports a hypothesis 'has little support in the medical profession or among scientists'." They were referring to a lone opinion. Here, by contrast to that, it was the lone opinion of Prof. Levi which contradicted two unquestionably qualified experts, supporting what Dr McCullagh claimed, without contradiction, to be "the hypothesis that … many people have proposed". 8 However, the Tribunal, having, as I have said, dismissed Dr Grygiel from consideration, held Dr McCullagh's sub-hypothesis to be "fanciful", by accepting "that Dr Levi has convincingly demonstrated that the hypothesis put forward by [sic] carcinoma of the oesophagus is not a reasonable one in that its basic premise, namely the affinity of cell types of the pancreas and oesophagus, is not scientifically correct. To state that cell types may have had a common origin is not to say that they are the same." But, of course, Dr McCullagh had never suggested the cell types were the same. His point was their common origin – which was not in dispute. Had it been in dispute, the Tribunal could hardly have rejected the views of the only embryologist in the case. From the common origin, he deduced the risk of a common susceptibility to the effects of a particular class of carcinogen. He said there "has been a well established practice among experimental pathologists, when one is looking at the susceptibilities and the ways in which a particular cell type can go wrong, to look back to the cell type in which that arises and say, well, what is that susceptible to? … [I]f two mature parts of an organ system are derived from a common cell of origin, one will have a reasonably high index of suspicion that they will have a shared susceptibility to a particular … cancerous transformation because of that origin. Because the formation of a cancer … does not occur primarily in the mature cell. … [C]arcinomas arise from the cells that have not completely differentiated." It was on this basis that, given studies associating DDT with cancers of the stomach and the pancreas, Dr McCullagh considered "one should suspect [DDT as possibly related to] any tumours in any part of the gut … derived from endoderm", and therefore as related to any adenocarcinoma of the oesophagus which, by definition, involves cells of the same derivation. 9 There is nothing in Dr McCullagh's reasoning which is contrary to any known fact, or obviously fanciful. That another specialist described it as "fanciful" and denied its validity is not enough: Bushell ubi cit supra. Indeed, in Bushell it appears (at 417) that the very same epithet "fanciful" was bestowed by the Commission's evidence upon the hypothesis there proposed. Dr Levi did not expose any logical fallacy in Dr McCullagh's evidence; his assertion of a different opinion does not make the hypothesis unreasonable, but merely raises a question for the next stage of the inquiry – whether the hypothesis, though reasonable, can be rejected beyond reasonable doubt. As to the logic, it is interesting to note that Dr Levi was himself prepared, in a different context, and against the appellant, to apply the same logic to the other carcinogen which had apparently been suggested to him, that arising from cigarette smoke. He wrote: "Evidence with regard to an association between cigarette smoking and adenocarcinoma of the oesophagus is probably best related to that of carcinoma of the stomach because of the biological similarity of these conditions. That is, adenocarcinoma of the oesophagus generally arises at the junction of the oesophagus and stomach and behaves biologically like carcinoma of the stomach." 10 When the Tribunal decided between Dr McCullagh and Dr Levi, it erred fundamentally, not merely because it ignored the wider hypothesis put forward by Dr Grygiel with which Dr McCullagh's sub-hypothesis, while supporting it, was consistent, but because it decided the validity of the conclusion each hypothesis suggested. That was to overlook the nature of a hypothesis which, as this Court pointed out in Repatriation Commission v Whetton (1991) 31 FCR 513 at 515-516, "is by definition speculative", being, in the medical sense in which it is used in s 120 of the Veterans' Entitlements Act 1986 (Cth), "a supposition or conjecture put forth to account for known facts". The question is not whether it is true, but whether it is a reasonable hypothesis raised by the facts. The ultimate conclusion comes later, and must be made in favour of the appellant unless her case can be rejected beyond reasonable doubt. 11 Finally, the Tribunal founded its conclusion on the proposition that Dr Levi had shown Dr McCullagh's "basic premise, namely the affinity of cell types of the pancreas and oesophagus, is not scientifically correct." But this is just the way the Tribunal is not entitled to use opposing medical evidence. It is "the validity of the reasoning", not the premise, for the assessment of which the High Court, in Bushell (at 415), sanctioned regard being had to opposing material. There is good reason why the Court so limited the use to be made of such material, while emphasizing it was "vital" to keep in mind that a hypothesis "may still be reasonable although it is unproved and opposed to the weight of informed opinion". For if the premise is to be rejected because another doctor disagrees with it, what happens to the principle, enshrined in the Act over many years, that a claim may only be declined if proven to be without sufficient ground, beyond reasonable doubt? No such onus is applied when the existence of a reasonable hypothesis is being considered, and there is no suggestion, in the Tribunal's reasons in the present case, that it was satisfied beyond a reasonable doubt – it said it was "satisfied", and was "deemed to be satisfied beyond reasonable doubt" because of its view that the hypothesis was "not a reasonable one". 12 The rejection of the hypothesis by the rejection of its "basic premise" thus inverted the proper order of consideration of the elements of the problem, thereby depriving the appellant of the benefit of the statutory onus in her favour. The true position is succinctly stated in Byrnes at 570-571: "Once a reasonable hypothesis is raised, the question for the Commission is then whether it is satisfied beyond reasonable doubt that there is no sufficient ground for making a determination that the injury was war-caused. The Commission will be so satisfied if it is satisfied beyond reasonable doubt that the factual foundation of the hypothesis has been disproved (Bushell (1992) 175 CLR, at p 416), either by proof beyond reasonable doubt that a factor fact[s] relied upon to support the hypothesis is not true, or by proof beyond reasonable doubt of the truth of a further fact, inconsistent with the hypothesis. [I have corrected "fact" to "facts" by reference to the report of the judgment in 116 ALR 210 at 215.] … The position may be summarized as follows: (1) First, sub-s. (3) of s. 120 is applied: do all or some of the facts raised by the material before the Commission give rise to a reasonable hypothesis connecting the veteran's injury with war service? The hypothesis will not be reasonable if it is contrary to known scientific facts or is obviously fanciful or untenable. If the hypothesis is not reasonable, the claim fails. Proof of facts is not in issue at this point. (2) If a reasonable hypothesis is established, sub-s. (1) of s. 120 is applied. The claim will succeed unless: (a) one or more of the facts necessary to support the hypothesis are disproved beyond reasonable doubt; or (b) the truth of another fact in the material, which is inconsistent with the hypothesis, is proved beyond reasonable doubt, thus disproving, beyond reasonable doubt, the hypothesis." 13 For these reasons, I would allow the appeal with costs; set aside the orders below; and in lieu of those orders set aside the decision of the Administrative Appeals Tribunal with costs and remit the matter to the Tribunal to be determined according to law. I certify that the preceding thirteen (13) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Burchett. Associate: Dated: 12 October 1999 IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NG 952 of 1998 ON APPEAL FROM A JUDGE OF THE FEDERAL COURT OF AUSTRALIA BETWEEN: LILLIAN ISOBEL WHEELDON Appellant AND: REPATRIATION COMMISSION Respondent JUDGE: BURCHETT, Branson AND RD NICHOLSON JJ DATE: 12 OCTOBER 1999 PLACE: SYDNEY REASONS FOR JUDGMENT BRANSON J Background 14 The appellant ("Mrs Wheeldon") is the widow of Alfred George Wheeldon ("Mr Wheeldon") who died on 18 January 1994 as a result of carcinoma of the oesophagus. Mr Wheeldon had served during World War II with the 2nd Australian Independent Farm Platoon in New Guinea and New Britain. In the course of this service he was exposed to dichlorodiphenyltrichloroethane ("DDT"), a powerful organochlorine insecticide. 15 Prior to his death, Mr Wheeldon had lodged a claim for pension and medical treatment under the Veterans' Entitlement Act 1986 (Cth) ("the Act") on the basis that his carcinoma of the oesophagus was caused by exposure to DDT during his service. On 21 March 1994, Mrs Wheeldon claimed a widow's pension on the same basis. Both claims were refused by a delegate of the respondent who determined that Mr Wheeldon's disease was not war-caused. 16 Mrs Wheeldon appealed to the Veterans' Review Board which affirmed the decision of the delegate. A further appeal to the Administrative Appeals Tribunal ("the Tribunal") also resulted in the delegate's decision being affirmed. Mrs Wheeldon brought an "appeal" to this Court from the decision of the Tribunal. On 20 August 1998 a judge of this Court (Whitlam J) dismissed the appeal. Mrs Wheeldon now appeals to this Court from the decision of Whitlam J. Veterans' Entitlements Act 1986 (Cth) 17 Part II of the Act is concerned with pensions, other than service pensions, for veterans and their dependants. Section 13(1) of the Act, which is in Division 2 of Part II, provides, so far as is here relevant: "13(1) Where: (a) the death of a veteran was war-caused; or (b) [not here relevant] the Commonwealth is, subject to this Act, liable to pay: (c) in the case of the death of the veteran – pensions by way of compensation to the dependants of the veteran; or (d) [not here relevant] in accordance with this Act." 18 It is accepted in this case that Mr Wheeldon was a veteran and Mrs Wheeldon was a dependant of his, within the meaning of s 13 of the Act. 19 Section 120 of the Act contains provisions dealing with standard of proof. So far as is here relevant, s 120 provides as follows:- "120 (1) Where a claim under Part II for a pension in respect of the incapacity from injury or disease of a veteran, or of the death of a veteran, relates to the operational service rendered by the veteran, the Commission shall determine that the injury was a war-caused injury, that the disease was a war-caused disease or that the death of the veteran was war-caused, as the case may be, unless it is satisfied, beyond reasonable doubt, that there is no sufficient ground for making that determination. (2) [not here relevant] (3) In applying subsection (1) or (2) in respect of the incapacity of a person from injury or disease, or in respect of the death of a person, related to service rendered by the person, the Commission shall be satisfied, beyond reasonable doubt, that there is no sufficient ground for determining: (a) that the injury was a war-caused injury or a defence-caused injury; (b) that the disease was a war-caused disease or a defence-caused disease; or (c) that the death was war-caused or defence-caused; as the case may be, if the Commission, after consideration of the whole of the material before it, is of the opinion that the material before it does not raise a reasonable hypothesis connecting the injury, disease or death with the circumstances of the particular service rendered by the person. (4) [not here relevant] (5) Nothing in the provisions of this section, or in any other provision of this Act, shall entitle the Commission to presume that: (a) an injury suffered by a person is a war-caused injury or a defence-caused injury; (b) a disease contracted by a person is a war-caused disease or a defence-caused disease; (c) the death of a person is war-caused of defence-caused; or (d) a claimant or applicant is entitled to be granted a pension, allowance or other benefit under this Act. (6) Nothing in the provisions of this section, or in any other provision of this Act, shall be taken to impose on: (a) a claimant or applicant for a pension or increased pension, or for an allowance or other benefit, under this Act; or (b) the Commonwealth, the Department or any other person in relation to such a claim or application; any onus of proving any matter that is, or might be, relevant to the determination of the claim or application. (7) [not here relevant]." 20 It is accepted in this case that Mrs Wheeldon's claim under Part II of the Act for a widow's pension relates to "operational service" rendered by Mr Wheeldon within the meaning of s 120(1) of the Act. 21 Sections 120A and 120B of the Act now impinge on the operation of s 120 of the Act. However, ss 120A and 120B only apply to claims made on or after 1 June 1994. They have no application in the circumstances of this case. Decision of the Tribunal 22 The Tribunal identified the hypothesis said to establish the causal link between the veteran's war service and his death as the hypothesis advanced by Dr Peter McCullagh that repetitive heavy exposure to DDT during the course of Mr Wheeldon's service constituted "a risk factor" for the subsequent development of carcinoma of the oesophagus. In a written report Dr McCullagh stated: "Studies specifically concerned with possible relationships between exposure to DDT and oesophageal cancer have not been published (nor have the results of any epidemiological studies which sought, and failed to find, such associations). However, DDT exposure has been incriminated as a risk factor for cancers in another part of the gastro-intestinal system, the pancreas … Pancreas and oesophagus are both components of the gastrointestinal system and they share a common major risk factor for carcinogenesis in tobacco smoking. I believe that epidemiological study to test for such an association would, in the light of recent progress in investigation of DDT as a human carcinogen, be now quite reasonable." 23 Dr McCullagh also referred in his oral evidence to the results of a Danish study published in 1982 which reported an association between the occurrence of some cancers, particularly cancer of the stomach, cervix, ovaries and prostate, and the presence of DDE, a long lasting break down of DDT. Dr McCullagh asserted that Mr Wheeldon's cancer, being an adenocarcinoma, can effectively be regarded, when one is looking for aetiologies, in terms of being a carcinoma of the stomach. 24 Two letters written to the applicant by Dr J. Grygiel, Associate Professor of Medicine and Senior Staff Oncologist at St. Vincents Hospital where Mr Wheeldon received radiotherapy, were also placed in evidence before the Tribunal. In summary, Dr Grygiel expressed the view in his letters that a possible link between DDT exposure and the development of oesophageal cancer "was a reasonable theory to explore" and referred to "the evidence accruing of the emergence of an increased incidence of various cancers that would appear to be related to exposure to DDT in the distant past". 25 Professor John Anthony Levi, the Director of Oncology at Royal North Shore Hospital, Sydney gave evidence to the Tribunal by way of written report that: "[t]here is no experimental, epidemiological or clinical evidence to support an association between exposure to DDT of any degree, intensity or duration and carcinoma of the oesophagus." 26 Professor Levi also stated in a report: "It has been suggested that because carcinoma of the pancreas is a gastrointestinal malignancy, there would therefore be an association between this and carcinoma of the oesophagus. Whilst it is true that the pancreas arises within the abdominal cavity, it is a distinct organ and not part of the gastrointestinal tract. To extrapolate that because both oesophagus and pancreas are intra-abdominal organs relates them in some way to etiology, is at the very least fanciful." 27 Under cross-examination, Professor Levi refuted the suggestion that the origin of the cells of the pancreas and the oesophagus was similar and affirmed that he certainly thought that "it is fanciful to draw comfort … from the positive findings regarding pancreatic cancer to oesophageal cancer where it is an adenocarcinoma of the oesophagus." 28 The Tribunal expressed its satisfaction that Professor Levi had convincingly demonstrated that the hypothesis said to establish the causal link between Mr Wheeldon's war service and his death was not a reasonable one "in that its basic premise, namely the affinity of cell types of the pancreas and oesophagus, it not scientifically correct." The Tribunal was convinced by Professor Levi's evidence that the hypothesis put forward by Dr McCullagh was fanciful. The Tribunal concluded that it was "deemed" to be satisfied beyond reasonable doubt that there is no sufficient ground for determining that Mr Wheeldon's death from cancer of the oesophagus was war-caused. Reasons of the Primary Judge 29 It was not contended before Whitlam J, or indeed before this Court, that the Tribunal erred in its identification of the hypothesis said to establish the causal link between Mr Wheeldon's eligible war service and his death or in its identification of the material said to support that hypothesis. Before Whitlam J the appellant sought to identify error in the Tribunal's consideration of the matter by contending that the Tribunal looked for proof of the validity of the hypothesis rather than looking to see if a reasonable hypothesis had been established. Further, the appellant contended before Whitlam J that the Tribunal had erred "by balancing competing theories" contrary to what Beaumont J said in East v Repatriation Commission (1987) 16 FCR 517 at 532. 30 Whitlam J rejected both of these submissions by reference to the decision of the Full Court in Repatriation Commission v Bey (1997) 79 FCR 364, a decision published later than the date of the notice of appeal against the decision of the Tribunal. His Honour referred to the statements made by Northrop ACJ, Sundberg, Marshall and Merkel JJ in Bey's case at 372 that: "While a hypothesis may be no more than a possibility or supposition, in order for a hypothesis to be reasonable, it must … be pointed to or supported, and not merely left open as a possibility, by the material before the decision-maker." and at 373, that: "Whether material raises a "reasonable hypothesis" for the purposes of s 120(3) is a question of fact for it involves no more than a determination whether a hypothesis of connection is reasonable: Repatriation Commission v Owens (1996) 70 ALJR 904". 31 Whitlam J concluded that the Tribunal had applied s 120(3) of the Act consistently with the first and second steps identified by Northrop ACJ, Sundberg, Marshall and Merkel JJ in Bey's case and held that "the Tribunal was entitled to conclude that in those circumstances the material did not raise a reasonable hypothesis connecting Mr Wheeldon's disease with his war service." 32 His Honour also concluded that for the Tribunal to examine the validity of the basis for a hypothesis is not to choose between hypotheses in the sense enjoined by the High Court in Bushell v Repatriation Commission (1992) 175 CLR 408 per Mason CJ, Deane and McHugh JJ at 415. 33 His Honour dismissed the appeal. Grounds of Appeal 34 The grounds of appeal pressed before this Court were: "3. His Honour erred in that he held that the principles enunciated in the case of Repatriation Commission v Bey (1997) 149 ALR 721 [(1997) 79 FCR 364] applied in the instant case. 4. His Honour erred in not holding that the evidence of exposure to DDT was a fact pointing to a reasonably hypothesis. 5. His Honour should have held that the Administrative Appeals Tribunal erred in preferring the evidence of some medical experts to others in determining if a reasonably hypothesis was raised." 35 The substance of the argument advanced by the appellant was that in a case such as the present, where two eminent medical practitioners give opposing evidence, it is not for the Tribunal to chose between them, in the sense of preferring the evidence of one to the evidence of the other. The role of the Tribunal, it was argued, was rather to assess whether or not there is a reasonably hypothesis and it will be almost impossible, if not impossible, to suggest that a hypothesis squarely advanced by an eminently qualified person is not reasonable simply because another person similarly qualified does not accept it. Consideration 36 As Northrop ACJ, Sundberg, Marshall and Merkel JJ pointed out Bey's at 366-367, the method of applying s 120(1) and (3) is now well established. Their Honours identified that method as follows: "(1) One commences with subs (3). The first step is to identify the hypothesis said to establish the causal link between the veteran's eligible war service and the death, injury or disease. Identifying the hypothesis is a question of fact. (2) The second step under subs (3) is to determine whether the hypothesis is reasonable. The material will raise a reasonable hypothesis if it points to some fact or facts which support the hypothesis (the "raised facts") and if the hypothesis can be regarded as reasonable assuming the raised facts to be true. In determining whether the hypothesis is reasonable the decision-maker must identify the facts said to point to it. (3) Whether a hypothesis is reasonable is a question of fact. The decision-maker must be satisfied that the hypothesis is reasonable after considering the whole of the material. Proof of facts and onus of proof are not in issue at this point. (4) If the decision-maker concludes that the material raises a reasonable hypothesis, the third step is reached. Subsection (1) must be applied, and the claim will succeed unless one or more of the facts necessary to support the hypothesis are disproved beyond reasonable doubt, or the truth of another fact in the material, which is inconsistent with the hypothesis, is proved beyond reasonable doubt, thus disproving, beyond reasonable doubt, the hypothesis. In some cases the hypothesis may assume the occurrence or existence of a "fact". That itself does not make the hypothesis unreasonable: Byrnes at 570 and Critch v Repatriation Commission (1996) 43 ALD 574 at 577." 37 The issue raised by this appeal is that of whether it was open to the Tribunal to conclude that the hypothesis said to establish the causal link between Mr Wheeldon's death and his war service was not a reasonable hypothesis. This issue is one of fact to be determined by reference to the whole of the material before the Tribunal (Repatriation Commission v Owens). 38 The expert evidence before the Tribunal in this case was complex and it is necessary for it to be examined in some detail. In view of the way in which the hearing before the Tribunal was conducted, it is sufficient for that examination to extend only to the evidence of Dr McCullagh and Professor Levi. 39 The critical passage from Dr McCullagh's written report concerning Mr Wheeldon is set out in para 22 above. 40 Dr McCullagh acknowledged that there is no evidence directly linking exposure to DDT with oesophageal cancer. The hypothesis proposed by him was dependant upon his conclusion that there was reason in Mr Wheeldon's case to regard a risk factor identified in respect of the pancreas to extend to the oesophagus. This is made clear in the following passage from Dr McCullagh's oral evidence: "So the hypothesis I advance is very much based on the fact that Mr Wheeldon suffered not from a squamous cell carcinoma of the oesophagus but from an adenocarcinoma of the oesophagus which is derived embyologically from endoderm in the same way as the stomach, small intestine, large intestine and the ducts which give rise to the pancreas. So for this reason there is – there tends to be a or has been a well established practice among experimental pathologists when one is looking at the susceptibilities and the ways in which a particular cell type can go wrong to look back to the cell type in which that arises and say well, what is that susceptible to?" 41 Dr McCullagh expanded on the relevance of Mr Wheeldon's having suffered from adenocarcinoma of the oesophagus in his oral evidence as follows: "… the feature of Mr Wheeldon's case which … I find particularly compelling is that he did not have a squamous cell carcinoma of the gut. He had what is … an adenocarcinoma of the oesophagus …. Adenocarcinoma of the oesophagus is known I think reasonably confidently now to arise from bits of small areas of lining of the stomach which have translocated – have gone north so to speak, and become established in the oesophagus and this has been – was described originally by a gastro-enterologist called Barrett, and so it has tended to be referred to as Barrett's oesophagus." 42 Under cross examination Dr McCullagh said: "… my conclusions are based on the embryological origins of the gut from endoderm, the fact that this tumour has arisen from endoderm …. All of the evidence as I mentioned earlier from the condition of Barrett's oesophagus is that you have got normal cells in an abnormal location, that is you have endoderm derived cells, cells that are part and parcel of the gastric mucosa have found their way north of the diaphragm during embryological development and my associating those with pancreatic cells and pancreatic tumours is entirely based on the shared embryological origin of the Barrett's oesophagus and of the ducts and glandular acini component of the pancreas." 43 In commenting on Professor Levi's report concerning Mr Wheeldon, Dr McCullagh said: "I believe that he has ignored the embryological evidence … that cells which have a common origin embryologically are likely to share common risk factors. … if we were talking about a squamous cell carcinoma of the oesophagus I would agree entirely with him …." 44 The overall effect of the evidence of Professor Levi is summarised in paras 25-27 above. It is important to note that Professor Levi challenged directly Dr McCullagh's evidence that significance is to be attached to the fact that Mr Wheeldon suffered from an adenocarcinoma; that is, a carcinoma of cells derived embryologically from endoderm. It is necessary to refer in more detail to certain aspects of Professor Levi's oral evidence. 45 When asked to comment on Dr McCullagh's evidence as to the common endodermal origin of tissue in the Barrett's oesophagus and tissue in the pancreas, Professor Levi said: "… it is important to recognise when we talk about endoderm then we assess that as part of the very basic embryological components of a human and if you then take that a little further you also talk about ectoderm as one of those components and mesoderm as one of those components and they all then split over time, develop into specific organs. Now certainly in the gastrointestinal tract includes endoderm from the lower end of the oesophagus through to the rectum and pancreas also is comprised of endoderm as is breast, as is ovary, as is prostate and many other tissues and organs. Now we recognise that carcinomas occur in all of those particular organs and they are all called adenocarcinomas. Adenocarcinoma means a carcinoma arising in adenoid type tissue … but the risk factor that we recognise for each of those carcinomas regularly differ enormously so that for example a risk factor for carcinoma of the colon can be and is very different to risk factors associated with carcinoma of the oesophagus in the same way as risk factors for breast cancer are very different to risk factors for pancreatic cancer. So to extrapolate that a proposed, and I emphasise the word proposed, risk factor for carcinoma of the pancreas based on one, admittedly good study, and then extrapolate that to oesophageal carcinomas [is] to my mind fanciful. There is no evidence whatsoever to suggest that such an association can be made." 46 When asked whether there is "a scientific principle or something in science whereby [cells] do have a common origin therefore one can make a supposition that [if] it could affect one type of cell [then] it should affect another", Professor Levi replied: "Not really. The only commonality amongst them is that if disturbances of growth and division within that tissue occurs it is given a common name …. But the actual genetic make up of those cells, while it has some commonality to make it in the first place endoderm, also has many differences than make it into the specific tissue and organ that it becomes. So that the genetic make up has some commonality but many differences as well and the environment to which it is exposed subsequently on the basis of its site and its characteristics also differ enormously so when you get to start talking about the causation of the cancer you move right away from the embryological origins and start to look at many other factors as well." 47 In response to a question as to the relevance of the condition known as Barrett's oesophagus in the light of the fact that Mr Wheeldon suffered from an adenocarcinoma of the oesophagus, Professor Levi responded: "None, no [Barrett's] oesophagus is a pre-malignant condition, that because of the metaplasia that occurs within which is the disturbance of the cellular division which occurs within the lining of that particular anomaly it then results in it going on ultimately to change from being abnormal in the sense of still being similar to normal but not quite, to being increasingly abnormal to ultimately it becomes malignant. So it is a pre-malignant condition. So from that point of view it is a precursor to malignancy, but that doesn't in any way associate it with specific risk factors or environmental." 48 The following is a passage from the cross examination of Professor Levi: "As to Barrett's oesophagus which you were just speaking about, you said it was a pre malignant condition, is it a necessary pre condition for an adenocarcinoma to develop? --- No, it is not. What is the mechanism whereby an adenocarcinoma of the oesophagus could develop without Barretts oesophagus first being there? --- The most common form of adenocarcinoma is that within the lower third of the oesophagus there are regularly as present columnar-epithelium which is not specifically Barretts oesophagus and there is also in many individuals an extension of the endothelium of the stomach up into the lower third of the oesophagus and as such it has therefore a similar lining to the stomach and has the potential to become an adenocarcinoma if it becomes malignant. So for an adenocarcinoma to arise in the oesophagus there has to be material of the same cell origin as we find in the pancreas, stomach and so forth? --- No, certainly the same cellular origin as the stomach, but the only similarity to the cell within the pancreas is that it is still a cell that is called the columnar type, in other words it looks like and it is an endothelial cell, but as I have explained it is an endothelial cell of a pancreas as distinct from an endothelial cell of the oesophagus or stomach. So it is a different cell. But do you agree that in the foetus this area from the base of the oesophagus down to near the end of the rectum is constituted by one cell type? --- Well it depends on your definition, what you mean by one cell type. If you mean those that are classified as endothelial cells under the light microscope the answer yes, they are endothelial cells. But if you ask me are they all exactly the same, the answer is they are not. What are the differences? --- The differences are those cells then create characteristics which relate to the specific organ to which they comprise, so that there are cells that relate to pancreas are different to those of the oesophagus to those of the colon and to those of the ovary to those of the breast and so on." 49 When asked by the cross examiner: "Do you still say it is fanciful to draw comfort if you like from the positive findings regarding pancreatic cancer to oesophageal cancer where it is an adenocarcinoma of the oesophagus:" Professor Levi replied: "I certainly do." Professor Levi was then asked: "Would you not regard the finding relating to a positive link between pancreatic cancer and DDT exposure as the basis for an assumption that there would be a similar finding if there was any way to carry out an experiment regarding an adenocarcinoma of the oesophagus and exposure to DDT?" He replied: "No, I would not. It is possible to carry out such an experiment in the same way as they have carried out that experiment for carcinoma of the pancreas. But no, I do not see that as being a valid basis for conducting the experiment. A valid basis for conducting such an experiment may well be that there are being cases of carcinoma of the oesophagus found to have evidence of DDT involvement of prior exposure to DDT and so on. That is the usual basis, but to say that because it is an adenocarcimoma of the pancreas or an adenocarcinoma therefore all adenocarcinomas may well be associated with DDT exposure is fanciful." 50 The Tribunal considered the expert evidence before it. It referred to the observation of Mason CJ, Deane and McHugh JJ in Bushell v Repatriation Commission (1992) 175 CLR 408 at 414 that: "a hypothesis cannot be reasonable if it is 'contrary to proved scientific facts or to the known phenomena of nature'. Nor can it be reasonable if it is 'obviously fanciful, impossible, incredible or not tenable or too remote or too tenuous'". 51 The Tribunal then expressed its satisfaction "that Dr Levi has convincingly demonstrated that the hypothesis put forward by (sic) carcinoma of the oesophagus is not a reasonable one in that its basic premise, namely the affinity of cell types of the pancreas and oesophagus, is not scientifically correct". 52 The issue before the Court is not whether it would have reached the same conclusion as the Tribunal but whether Whitlam J erred in concluding that it was open to the Tribunal on the material before it to find, as a matter of fact, that the hypothesis advanced by Dr McCullagh was not "reasonable" in the sense explained by the majority of the High Court in Bushell's case. 53 Having regard to the evidence set out above it was, in my view, open to the Tribunal to reach the conclusion that it did. In doing so it did not, in my view, form its own view of "competing medical theories" in the sense in which that expression was used by Brennan J in Bushell's case at 430. I understand Brennan J to be there referring to theories of medical science asserting or denying "a connexion between a particular morbid condition and a postulated cause" (see his Honour's consideration of s 130(3) at 427 of the same report). It may be assumed, it seems to me, that Brennan J did not intend to refer to a theory asserting, or denying, a connection between a morbid condition and a postulated cause which was not a reasonable theory. His Honour, as I understand the relevant passage from his judgment, was concerned to stress that a theory or hypothesis does not cease to be reasonable in the statutory sense merely because it is not the only hypothesis concerning the aetiology of the morbid condition which may in the circumstance sensibly be postulated, or indeed, may not even be the hypothesis found by the decision-maker to be the most compelling. 54 The Tribunal was not in this case faced with competing medical theories in the above sense. It was faced with one hypothesis only: the hypothesis being that which was most fully developed in the oral evidence of Dr McCullagh. The Tribunal was required to determine as a matter of fact whether that hypothesis was a reasonable one in the sense that it was not "obviously fanciful, impossible, incredible or not tenable or too remote or too tenuous." In my view, there was evidence before the Tribunal, namely that given by Professor Levi, upon which the Tribunal was entitled to conclude that the hypothesis advanced on behalf of the appellant was not a reasonable hypothesis. I agree with Whitlam J that the decision of the Tribunal evinces no error of law. 55 I would dismiss the appeal and hear counsel on the question of costs. I certify that the preceding forty-two (42) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Branson. Associate: Dated: 12 October 1999 IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NG 952 of 1999 ON APPEAL FROM A JUDGE OF THE FEDERAL COURT OF AUSTRALIA BETWEEN: LILLIAN ISOBEL WHEELDON Appellant AND: REPATRIATION COMMISSION Respondent JUDGE: BURCHETT, Branson AND RD Nicholson JJ DATE: 12 OCTOBER 1999 PLACE: SYDNEY REASONS FOR JUDGMENT RD NICHOLSON J 56 I have had the advantage of reading in draft the reasons of Burchett J and of Branson J. 57 Dr McCullagh testified that the hypothesis he advanced was very much based on the fact that the veteran suffered from an adenocarcinoma of the oesophagus. He further testified that the oesophagus is derived embryologically from endoderm in the same way as the stomach, small intestine, large intestine and the ducts which give rise to the pancreas. In his view, the veterans's cancer could be effectively regarded as a carcinoma of the stomach which had been misplaced into the oesophagus because the stomach lining had got its way into the oesophagus during the embryological development ("Barretts' oesophagus"). He said cells having a common embryology were likely to share common risk factors because the formation of the cancer was primarily more likely to come from the stem cells rather that the mature differentiated cells. He accepted this could not have been the case if the veteran's oesophageal cancer had been a squamous cell carcinoma. 58 It was necessary for this hypothesis to be tested for its reasonableness in the context of all the evidence before the Tribunal. Professor Levi's evidence was that the existence of Barrett's oesophagus was not a necessary precondition to development of an adenocarcinoma and that the most common form of adenocarcinoma of the oesophagus was not specifically Barrett's oesophagus. He also testified that the only cellular similarity between the oesophagus and the pancreas is that the cell of the former is of the columnar type but otherwise was different. 59 The full course of the evidence in which the reasonableness of Dr McCullagh's evidence was required to be considered is set out in the reasons for judgement of Branson J. 60 I agree with Branson J that, considered in that context, the Tribunal was entitled to conclude that the hypothesis was not reasonable in the sense explained by the majority of the High Court in Bushell v Repatriation Commission (1992) 175 CLR 408. I also agree with her Honour's reasons that in so concluding the Tribunal did not choose between competing medical theories. 61 For these reasons I concur with Branson J that the appeal should be dismissed. I certify that the preceding six (6) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Nicholson. Associate: Dated: 12 October 1999 Counsel for the Appellant: Mr A T McInnes QC with Mr C A Vindin Solicitor for the Appellant: Kenneth Harrison Counsel for the Respondent: Mr D Ryan Solicitor for the Respondent: Australian Government Solicitor Date of Hearing: 25 February 1999 Date of Judgment: 12 October 1999