Farrow-Smith v Comcare

Decision making and review 9 Section 54 of the SRC Act provides that compensation is not payable to a person under the Act unless a claim is made and provides for how a claim is to be made. Section 61 provides for a claim to be determined by a "determining authority" and for notice of the determination and its reasons to be served on the claimant. Section 62 requires the determining authority to reconsider a determination if a request is made by the claimant. 10 A decision under s 62 is a "reviewable decision" (see the definition in s 60). That means that it is required to be notified in writing (accompanied by a statement of reasons) as soon as practicable after the decision is made: s 63. Section 64(1) provides that the claimant may make an application to the Tribunal for review of a reviewable decision. 11 Section 25 of the AAT Act is headed "Tribunal may review certain decisions". Section 25(1) provides that an enactment may provide for applications to be made to the Tribunal to review decisions made in the exercise of powers conferred by that enactment. This is the source of the power (and the duty) of the Tribunal to "review" a decision made under an enactment. 12 Section 43(1) is central to the regime of the AAT Act. It provides: For the purpose of reviewing a decision, the Tribunal may exercise all the powers and discretions that are conferred by any relevant enactment on the person who made the decision and shall make a decision in writing: (a) affirming the decision under review; (b) varying the decision under review; or (c) setting aside the decision under review and: (i) making a decision in substitution for the decision so set aside; or (ii) remitting the matter for reconsideration in accordance with any directions or recommendations of the Tribunal. 13 The capacity of the Tribunal to exercise powers and discretions of the original decision maker, and to vary the decision under review or make a decision in substitution for it, distinguish it from a court. This is the foundation for well known statements in the cases to the effect that the Tribunal "stands in the shoes" of the original decision maker and its function is to "do over again" the task of that decision maker (see eg Miller v Minister for Immigration, Citizenship and Multicultural Affairs [2024] HCA 13; 98 ALJR 623 at [14] (Gageler CJ, Gordon, Edelman, Jagot and Beech-Jones JJ)). However, unlike most administrative decision makers, the Tribunal when conducting a review under the AAT Act proceeds in an adversarial manner. There are "parties" to the review, including the original decision maker (s 30(1)), who are entitled to appear in person or to be represented (s 32(1)). In most cases a public hearing is held (s 35(1)) where evidence may be taken on oath or affirmation (s 40). The Tribunal is required to give every party to a proceeding "a reasonable opportunity to present his or her case" (s 39). The Tribunal is also expressly empowered to make a decision in accordance with an agreement reached by the parties, without holding a hearing (s 42C). Thus, in proceedings under the AAT Act (of which the present was one), the evidence and arguments considered by the Tribunal are shaped to a significant degree by parties contending for different outcomes. This feature of the Tribunal is relevant to the application of principles of procedural fairness, which is considered below.

Compensation criteria 14 The circumstances in which compensation is payable are dealt with by Part II of the SRC Act. Relevantly to this case, s 14(1) provides: Subject to this Part, Comcare is liable to pay compensation in accordance with this Act in respect of an injury suffered by an employee if the injury results in death, incapacity for work, or impairment. 15 Although s 14 is expressed as imposing a liability in defined circumstances, it is in truth a criterion to be applied by the determining authority under s 61 (subject to review by the Tribunal and appeal on questions of law) rather than an objective trigger for liability. The determining authority or the Tribunal must be satisfied that an injury within the scope of s 14 has occurred, resulting in death, incapacity or impairment. The question for this Court in an appeal under s 44 of the AAT Act is whether, in failing to be so satisfied, the Tribunal erred in law. 16 "Injury" is defined by s 5A of the SRC Act, as follows. 5A Definition of injury (1) In this Act: injury means: (a) a disease suffered by an employee; or (b) an injury (other than a disease) suffered by an employee, that is a physical or mental injury arising out of, or in the course of, the employee's employment; or (c) an aggravation of a physical or mental injury (other than a disease) suffered by an employee (whether or not that injury arose out of, or in the course of, the employee's employment), that is an aggravation that arose out of, or in the course of, that employment; but does not include a disease, injury or aggravation suffered as a result of reasonable administrative action taken in a reasonable manner in respect of the employee's employment. (2) For the purposes of subsection (1) and without limiting that subsection, reasonable administrative action is taken to include the following: (a) a reasonable appraisal of the employee's performance; (b) a reasonable counselling action (whether formal or informal) taken in respect of the employee's employment; (c) a reasonable suspension action in respect of the employee's employment; (d) a reasonable disciplinary action (whether formal or informal) taken in respect of the employee's employment; (e) anything reasonable done in connection with an action mentioned in paragraph (a), (b), (c) or (d); (f) anything reasonable done in connection with the employee's failure to obtain a promotion, reclassification, transfer or benefit, or to retain a benefit, in connection with his or her employment. 17 It will be noted that one category of "injury" is a "disease". "Disease" is defined, by s 5B, as follows. 5B Definition of disease (1) In this Act: disease means: (a) an ailment suffered by an employee; or (b) an aggravation of such an ailment; that was contributed to, to a significant degree, by the employee's employment by the Commonwealth or a licensee. (2) In determining whether an ailment or aggravation was contributed to, to a significant degree, by an employee's employment by the Commonwealth or a licensee, the following matters may be taken into account: (a) the duration of the employment; (b) the nature of, and particular tasks involved in, the employment; (c) any predisposition of the employee to the ailment or aggravation; (d) any activities of the employee not related to the employment; (e) any other matters affecting the employee's health. This subsection does not limit the matters that may be taken into account. (3) In this Act: significant degree means a degree that is substantially more than material. 18 A condition suffered by an employee that leads to incapacity for work therefore amounts to an "injury", compensable under s 14, if: (a) it is a "disease" - ie, an ailment or an aggravation of an ailment "that was contributed to, to a significant degree, by the employee's employment"; or (b) it is an "injury (other than a disease)", or an aggravation of such an injury, "arising out of, or in the course of, the employee's employment". 19 "Ailment" is defined in s 4 to mean "any physical or mental ailment, disorder, defect or morbid condition (whether of sudden onset or gradual development)". There is an element of circularity in that definition, leaving the underlying concept of an "ailment" bearing its ordinary meaning. The underlying concept of an "injury" (which informs an "injury (other than a disease)") is not defined, except to the extent that it means a "physical or mental injury".

Underlying facts 20 It was not in doubt that Ms Farrow-Smith had been employed by the ABC as a journalist at all relevant times. It was also not in doubt that she had lived in the Northern Rivers region (apart from absences for study or work) since 1974 and that since 2002 she had lived in a particular part of Byron Bay. 21 The Tribunal accepted that Ms Farrow-Smith was assigned to cover floods in certain parts of the Northern Rivers region on 12, 13 and 14 February 2020 and that on these days (working with a different colleague on each day) she had filmed the floods at particular locations. 22 The Tribunal set out parts of Ms Farrow-Smith's evidence, and parts of a statement by a colleague, recounting that while filming at one of these locations on 14 February (and despite wearing long sleeves and insect repellent) she had been bitten by mosquitoes. She did not specify how many bites she thought she had received, but referred to an "attack" by a "swarm" of mosquitoes lasting around five minutes. The Tribunal accepted this evidence (at [217]). 23 Ms Farrow-Smith's evidence was that she then worked at the ABC offices in Lismore until 28 February 2020, when she was due to start long service leave. She did not feel very well on the evening of 26 February and by 28 February she "was feeling pretty bad". She visited a chemist on the way home and spent about $400 on a range of items including pain killers, temperature scans and vitamins. She was not thinking clearly and struggled to drive home. She spent the weekend in bed and then on 3 March 2020 travelled to Yamba for a short holiday with her mother. Her partner and son joined her later. During several days at Yamba she spent most of her time in bed. She went home, continued to deteriorate, and eventually saw a GP on 6 April 2020. (The Tribunal accepted that her delay in seeking medical attention was related to the circumstances of the COVID-19 pandemic and drew no adverse inferences from it.) 24 The Tribunal expressed "some problems" with this account (at [218]), even though it was corroborated by Ms Farrow-Smith's partner (noted at [220]), because it did not align with clinical notes by Dr Neil Hannah (the GP who saw Ms Farrow-Smith on 6 and 9 April 2020) (at [221] and [225]). The reasoning from this point proceeded as follows. 25 Dr Hannah had not been called to give evidence, so no view could be taken as to his credibility. However, the Tribunal took the view that his notes could be relied on as accurate, there being "no reason to doubt their veracity" (at [223]). 26 Dr Hannah's notes from 6 April 2020 (referred to at [226]-[227]) recorded that Ms Farrow-Smith came for influenza injections but was suffering from polyarthralgia in her hands, ankle and shoulder. Blood tests were ordered and her vaccination was postponed. The notes did not mention Ms Farrow-Smith having suffered debilitating symptoms for more than a month. 27 It was put to Ms Farrow-Smith in cross-examination (extracted at [228]) that the notes did not reflect a five week history of symptoms. Her answer was "No, because it was just a short consult for my son to get a flu vax basically". The Tribunal found that Ms Farrow-Smith did not mention to Dr Hannah that she had been suffering debilitating illness for six weeks (at [229]). (The difference between "more than a month" (at [227]), "five weeks" (the transcript extract at [228]) and "six weeks" (at [229]) does not appear to be significant.) 28 Next, Dr Hannah's notes from 9 April 2020 (discussed at [230]-[234]) recorded Ms Farrow-Smith telling him that she had had a sore throat a month ago and was "worried about EBV" (which I understand refers to Epstein-Barr Virus). The notes also include: … was down in yamba [sic] and got snmashed [sic] by mosquitoes. 29 The Tribunal observed at [233] that these notes again made no mention of prolonged illness. 30 The Tribunal also focused on the reference to being "smashed by mosquitoes" at Yamba. In cross-examination Ms Farrow-Smith denied saying this to Dr Hannah (noted at [235]), but the Tribunal was "not convinced by her answer" (at [236]). Because Dr Hannah "presumably" resided in the Byron Bay region, the Tribunal did not consider that there was any reason why Dr Hannah would confuse Yamba with some other place in the region where Ms Farrow-Smith said she had been bitten. It proceeded on the basis that the notes accurately reflected the information provided by Ms Farrow-Smith (at [237]). 31 Ms Farrow-Smith saw Dr Hannah on two other dates later in April 2020. The notes of those consultations did not say anything further about either long-standing symptoms prior to 6 April or whether Ms Farrow-Smith had been bitten by mosquitoes at Yamba (at [238]-[239]). 32 The Tribunal then turned to the notes made by Dr Gregory Gover (who apparently was Ms Farrow-Smith's usual doctor) on 6 May 2020 and a report that he provided to Comcare dated 7 July 2020 (the July 2020 report). According to Dr Gover's notes, Ms Farrow-Smith told him that she felt she had been bitten while on assignment at Coraki, and he advised that RRV was endemic in the area so that the illness might not be work related (at [245]-[246]). Dr Gover's report, which was quoted at some length, also accepted that the mosquito species that carry RRV were endemic in the region, so that it was not possible to say that Ms Farrow-Smith's infection certainly occurred as a result of being bitten at a particular time or place. The final part of the passage quoted (at [252]) said: I understand that Ms Farrow-Smith went to Yamba for a holiday in early March, and was attacked by mosquitoes there but had already begun to experience muscle aches in late February. This suggests that Ms Farrow-Smith may have been already symptomatic with Ross River Virus infection at this time. 33 At [256], the Tribunal appears to have found it significant that the reference to Ms Farrow-Smith being attacked by mosquitoes at Yamba in early March appears again in Dr Gover's July 2020 report. The Tribunal thought it "not conceivable" that he would have got this wrong and that he would "presumably" have spoken to Dr Hannah or Ms Farrow-Smith or both about the point. 34 From [257] to [268] the Tribunal diverted to two other matters which had been the subject of evidence. (a) The first was the evidence that Ms Farrow-Smith had felt ill in late February 2020. Dr Gover had observed in his July 2020 report that Ms Farrow-Smith had muscle aches and soreness on 28 February and this "would be consistent with an exposure to the virus around the time that Ms Farrow-Smith was reporting the flooding events and bitten by mosquitoes", but this was based on self-reporting some time later. The Tribunal accepted that Ms Farrow-Smith was unwell and experiencing body aches and pains on 26-28 February but did not consider that this took matters very far. The Tribunal observed that the evidence of two experts (Dr Marcus Navin and Professor Tony Korman) was that these symptoms could be related to other infections. (b) The second issue related to Ms Farrow-Smith's home. She gave evidence in relation to aspects of the home's construction and surroundings, evidently intended to show that she was unlikely to have been bitten by mosquitoes at home. The Tribunal accepted that the house had the attributes described, but did not consider the evidence significant because Ms Farrow-Smith's movements were not all accounted for (and it seems to have been uncontroversial that mosquitoes were very common throughout the Northern Rivers region). 35 The Tribunal then turned to the expert evidence, noting that it was impressed by the evidence of Dr Navin and Professor Korman (at [269]). The key points (discussed at [269]-[275]) drawn from their evidence were as follows. (a) Antibodies to RRV, rather than the virus itself, are detected by blood testing. Two tests are taken at least 14 days apart. (b) There are two antibodies, referred to as IgM and IgG. (c) The IgM antibody indicates recent infection (appearing around four days after the onset of symptoms). (d) The IgG antibody is detected within around 10 days after onset of symptoms and remains indefinitely. (e) The incubation period (from infection to onset of symptoms) is almost always seven to nine days although shorter and longer periods (up to 21 days) had been reported in rare cases. 36 This understanding as to the incubation period was consistent with Dr Gover's opinion and with journal articles to which reference was made (at [276]-[283]). 37 Ms Farrow-Smith's blood sample taken on 7 April 2020 was IgM positive. A second sample taken on 24 April 2020 was positive for both IgM and IgG. Dr Navin opined that, based on the timings set out above, if Ms Farrow-Smith had been infected in February 2020, she would have had IgG antibodies by the time her first blood sample was taken on 7 April 2020 (at [291]). He further opined that the result from the sample taken on 7 April (IgM positive and IgG negative) suggested that the IgM antibodies would have arisen no more than 21 days following infection, which puts the infection date in mid-March (at [292] and [328]). 38 The contest in the expert evidence was between Dr Gover, who contended that Ms Farrow-Smith had a slow immune response (indicating that she had been infected somewhat earlier, and possibly in mid February 2020) and Professor Korman and Dr Navin who did not see a basis for this theory. The Tribunal generally preferred the opinion of Professor Korman and Dr Navin. 39 At the end of its discussion of the expert evidence, after referring to some of the cross-examination of Professor Korman by counsel for Ms Farrow-Smith, the Tribunal made the following observations (at [317]-[318]). The thrust of Ms Fraser's submissions is predicated on the Applicant first experiencing symptoms of Ross River Virus on or about 28 February 2020. Dr Gover's slowed response thesis is also predicated on that assumption. It should be noted that the Applicant's claimed symptoms of 28 February 2020 have only been corroborated by her partner, Mr D'errey. Importantly, Dr Gover did not treat the Applicant on 28 February 2020, and did not, in fact, examine her until early May 2020. His thesis about slowed response is, therefore, based entirely on the Applicant's self-reporting. 40 I observe that this passage mischaracterises Dr Gover's evidence to some degree. Dr Gover's delayed immune response thesis did not depend on Ms Farrow-Smith's "self-reporting" of her symptoms around 28 February 2020. The thesis was an attempt to reconcile the results of Ms Farrow-Smith's blood tests with a claim that those symptoms (the existence of which the Tribunal accepted) were symptoms of RRV. Similarly, the submissions for Ms Farrow-Smith sought to demonstrate that she had symptoms of RRV around 28 February; they were not "predicated" on that proposition. 41 The Tribunal then set out the following findings and conclusions. (a) Ms Farrow-Smith was bitten by mosquitoes on 14 February 2020 while filming floods for her employer ([320(b)]). (b) Ms Farrow-Smith began to feel unwell on 26 February 2020 ([320(c)]). (c) On 28 February 2020 Ms Farrow-Smith was feeling "pretty bad", suffering body aches and pains ([320(d)-(e)]). (d) There was no medical evidence that what she was suffering at this point was RRV ([321]). (e) There was no reason to doubt the accuracy of the notes of Dr Hannah, which recorded Ms Farrow-Smith being "smashed" by mosquitoes at Yamba ([323]-[324]) (as noted earlier, Ms Farrow-Smith was on holiday at Yamba in March 2020). (f) The evidence of Dr Navin and Professor Korman (who were preferred to Dr Gover) was that, based on the serology reports, Ms Farrow-Smith had been infected with RRV sometime in March 2020 ([327]-[330]). (g) The position was thus summarised (at [331]) as follows. Ms Fraser and Dr Gover invite the Tribunal to accept the Applicant's self-reporting of her condition in February and March 2020, and to further accept that she had a slowed immune response. The suggested slowed immune response is not based on medical science (other than Dr Gover's opinion), but rather involves ex post facto rationalisation of her blood tests and further involves the Tribunal attempting to reconcile those tests with the Applicant's apparently contradictory self-reporting. Even then, Ms Fraser invites the Tribunal to reject the accuracy of Dr Hannah's surgery notes that report that the Applicant told him that she had been "smashed" by mosquitoes in Yamba whilst visiting her mother. In short, the Applicant's case is built on conjecture, and is predicated on the medically unproven argument of slowed immune response. (emphasis in original) 42 The Tribunal was not able to say, however, that medical science excludes the possibility of a slowed immune reaction to RRV. Professor Korman, at least, did not go that far. The Tribunal said (at [340]): … We specifically note that we have not reached our conclusion by rejecting the possibility of a slowed immune reaction or that such a reaction may not be present in some persons for various medical reasons. (emphasis in original) 43 The Tribunal continued (at [341]-[345]): In reaching our conclusion, we make the following factual findings: (a) there is no record of the Applicant informing Dr Hannah on either 6, 9, 23 or 30 April 2020 that she had been suffering from debilitating illness since 28 February 2020; (b) apart from Mr D'errey, there is no other evidence before the Tribunal that would support the proposition that the Applicant was seriously ill from 28 February 2020 until 6 April 2020; (c) there is no evidence that the Applicant's illness, on or about 28 February 2020, was Ross River Virus; (d) the Applicant informed Dr Hannah that she had been "smashed" by mosquitoes in Yamba in March 2020; and (e) Dr Gover repeated this version of events at Yamba in his report of 7 July 2020 without contradicting it. We conclude that the Applicant's illness, on or about 28 February 2020, was not as a result of Ross River Virus. We further conclude that the medical science presented to the Tribunal, in the form of the Ross River virus serology of 7 and 24 April 2020, conclusively support the theses of Dr Navin and Professor Korman that the Applicant contracted Ross River Virus at some time after the first week of March 2020 and whilst she was on long service leave. In reaching this conclusion, we also find that there is no medical science presented to us, other than views of Dr Gover, that would support a finding of slowed immune reaction in the Applicant. For different reasons, both Dr Navin and Professor Korman gave compelling testimony that convinced the Tribunal that there was no secure medical evidence that would support such a hypothesis. Insofar as Dr Gover's support for the hypothesis is based on his belief that the Applicant was infected by Ross River Virus in February 2020, and which belief is based entirely on the Applicant's self-reporting, we prefer the opinions expressed by Dr Navin and Professor Korman. We note that the opinions expressed by Dr Navin and Professor Korman are based purely on proven medical science and are not based on subjective considerations. We, therefore, conclude that the Applicant's ailment, Ross River Virus, was not contributed to, to a significant degree, by her employment with the ABC.

The grounds of appeal 44 The grounds articulated in Ms Farrow-Smith's amended notice of appeal are as follows. (a) The Tribunal, being under a duty to arrive at the correct or preferable decision in the case before it according to the material before it, erred in law in failing to reach a decision that discharged the jurisdiction conferred upon it. (b) The Tribunal denied the applicant procedural fairness, by rejecting unchallenged evidence in breach of the rule in Browne v Dunn. (c) The Tribunal erred in law in failing give adequate reasons and make sufficient findings of fact to support its decision. (d) The Tribunal erred in law in finding, if it did so find, that RRV caused by a mosquito bite is a disease or an "injury (other than a disease)".

Grounds (a) to (c): treatment of the evidence 45 Grounds (a), (b) and (c) tended to merge into each other in the written and oral submissions. However, ground (b) is relatively specific and can be dealt with discretely.

Browne v Dunn 46 The so-called rule in Browne v Dunn (named after the case of that name: (1893) 6 R 67 (HL)) has been formulated by an experienced New South Wales judge in Allied Pastoral Holdings Pty Ltd v Federal Commissioner of Taxation [1983] 1 NSWLR 1 at 16 (Hunt J) as follows: It has in my experience always been a rule of professional practice that, unless notice has already clearly been given of the cross-examiner's intention to rely upon such matters, it is necessary to put to an opponent's witness in cross-examination the nature of the case upon which it is proposed to rely in contradiction of his evidence, particularly where that case relies upon inferences to be drawn from other evidence in the proceedings. Such a rule of practice is necessary both to give the witness the opportunity to deal with that other evidence, or the inferences to be drawn from it, and to allow the other party the opportunity to call evidence either to corroborate that explanation or to contradict the inference sought to be drawn. 47 The rule is a rule of fairness which applies in relation to witnesses, whether or not they are also parties, and applies to trial judges as well as legal practitioners: Bale v Mills [2011] NSWCA 226; 81 NSWLR 498 at [64] (Allsop P, Giles JA and Tobias AJA). 48 Although the Tribunal is not bound by the rules of evidence (AAT Act s 33(1)(c)), the rule in Browne v Dunn has been understood to be an aspect of procedural fairness "so that, subject to taking account of the particular statutory context and functions, its contravention may invalidate a decision of the Tribunal": Fenner v Repatriation Commission [2005] FCA 27; 218 ALR 122 at [60] (Mansfield J). This is consistent with the adversarial nature of proceedings under the AAT Act. (It is to be contrasted with reviews conducted under Parts 5 and 7 of the Migration Act 1958 (Cth), where the process is inquisitorial: Re Minister for Immigration and Multicultural Affairs; Ex parte Applicant S154/2002 [2003] HCA 60; 77 ALJR 1909 at [57] (Gummow and Heydon JJ, Gleeson CJ agreeing).) Thus, the decision of the Tribunal is liable to be set aside if it depended on a finding contrary to Ms Farrow-Smith's evidence without the point having been put to her in such a way that she could respond to it in her evidence. Practically, that is usually expected to be done in the course of cross-examination. 49 Although the Tribunal at one point described the expert evidence of Professor Korman and Dr Navin as conclusive, earlier in its reasons it expressly accepted the "possibility" that some individuals had slower than normal immune responses. The blood test results therefore did not entirely foreclose success for Ms Farrow-Smith, but pointed strongly towards her infection having been acquired in March 2020. The lay evidence was therefore not unimportant. 50 As to this, there was evidence (which the Tribunal accepted) that Ms Farrow-Smith had been unwell in late February. There was also her evidence (supported by that of her partner) that she had been largely bedridden during her holiday at Yamba in early March and remained unwell until she saw Dr Hannah on 6 April. The Tribunal was not bound to accept this evidence, but it was bound to adopt a fair procedure if the evidence was to be rejected.

"Smashed" by mosquitoes at Yamba 51 Ms Farrow-Smith's case faced two problems, one specific and one general. (a) The specific problem was that, according to Dr Hannah's notes, she reported to him that she had been "smashed" by mosquitoes while she was at Yamba (which was in early March 2020). If that happened, it was a potential source of infection - unrelated to Ms Farrow-Smith's employment - whose timing aligned fairly closely with what (according to Professor Korman and Dr Navin) was to be inferred from the serology reports. Unless mosquito bites at Yamba could be excluded (or shown to be no more than speculation), it would be extremely difficult for the Tribunal to be persuaded that the ailment suffered by Ms Farrow-Smith was "contributed to, to a significant degree, by [her] employment". (b) The more general problem was that it was uncontroversial that RRV was endemic in the Northern Rivers region. Ms Farrow-Smith gave evidence of the precautions taken to minimise mosquito activity in her house and garden (and that she did not recall being bitten at home), but she could not realistically exclude (and on my reading did not try to exclude) the possibility of having been bitten by a mosquito in February or March 2020 in circumstances not connected with her employment. 52 As to the specific problem, the Tribunal clearly regarded Dr Hannah's notes of the consultation on 9 April 2020 as a faithful record of what Ms Farrow-Smith said to him on that occasion: that is, Ms Farrow-Smith told Dr Hannah that she had been "smashed" by mosquitoes at Yamba. 53 Ms Farrow-Smith was taken to Dr Hannah's notes of 6 and 9 April in cross-examination, largely in an attempt to establish that she had not complained on those occasions of being continuously unwell since 28 February. The issue of mosquitoes at Yamba was touched on briefly, as follows. Did you tell him - sort of the next line - 'Was down in Yamba and got smashed by mosquitoes?'---No. I told him - he said where have you been, and I said that I've been - told him where I'd been, but I didn't say that I was in Yamba and got smashed by mosquitoes. That doesn't follow. 54 It was thus put to Ms Farrow-Smith that she had said words to the effect of what was recorded in Dr Hannah's notes. However, the important issue was not the contents of her conversation with Dr Hannah but whether, in fact, she had sustained a significant number of mosquito bites at Yamba. Although it does not clearly state a finding in these terms, the emphasis on Dr Hannah's notes is hard to explain unless such a finding was being made implicitly. The Tribunal must be taken to have found at least a significant likelihood that Ms Farrow-Smith was bitten during her time at Yamba (so that infection in March was a more persuasive explanation for the serology results than infection in February combined with a delayed immune response). 55 The proposition that Ms Farrow-Smith had suffered a significant number of mosquito bites at Yamba was not put to her directly. Nor was it sufficiently clearly implicit in the questions she was asked about Dr Hannah's notes to make later reliance on the proposition fair. Ms Farrow-Smith had in fact given evidence directly to the contrary of this proposition in her witness statement dated 14 April 2021 at [78]: "I did not get bitten by mosquitos [sic] at Yamba". She adopted this statement in her evidence in chief. She was not challenged on this aspect of it. 56 It will also be recalled that Dr Gover's July 2020 report noted his understanding that Ms Farrow-Smith had been bitten by mosquitoes at Yamba. In cross-examination, Dr Gover was taken to notes he made on 6 July 2020 which recorded that "when first diagnosed reports being in yamba [sic] about one month before being seen and 'smashed by mosquitos'". Dr Gover agreed with a suggestion by the cross-examiner that this was a matter he would have spoken to Ms Farrow-Smith about on 6 July. If this is taken to mean that Dr Gover's understanding of events at Yamba came from Ms Farrow-Smith, it was evidence of another prior inconsistent statement by her. It was not raised with her in cross-examination. 57 The Tribunal appears to have regarded this evidence as significant. At [256] of its reasons it observed that "Dr Gover refutes the Applicant's case that she was not 'smashed' by mosquitoes at Yamba" (emphasis in original). Dr Gover, of course, could not give any direct evidence about what happened to Ms Farrow-Smith at Yamba. The Tribunal was evidently relying on Dr Gover having taken a history from Ms Farrow-Smith (consistent with what was in his notes and his report) as persuasively contradicting her direct evidence of what occurred. It did this without anybody having put to Ms Farrow-Smith that her evidence was incorrect in this important respect. 58 In these respects, the Tribunal failed to afford procedural fairness to Ms Farrow-Smith. Subject to the issue to be discussed next, its decision should be set aside. 59 In judicial review under s 75(v) of the Constitution and its analogues, where a grant of relief depends on establishing jurisdictional error, a failure to provide a fair procedure is regarded as going to jurisdiction only if it is shown to have denied the applicant a prospect of a successful outcome. This is an aspect of the doctrine of materiality as explained in recent cases including, for example, MZAPC v Minister for Immigration and Border Protection [2021] HCA 17; 273 CLR 506. The analysis is different in an appeal on questions of law, where the error identified need not be one that goes to jurisdiction. A failure to afford procedural fairness is an error of law for the purposes of s 44 of the AAT Act: Clements v Independent Indigenous Advisory Committee [2003] FCAFC 143; 131 FCR 28 at [6]-[8] (Gray ACJ and North J). However, an error of law does not justify an order under s 44(4) setting aside the decision of the Tribunal unless the error rises above a threshold of materiality. In Comptroller-General of Customs v Pharm-A-Care Laboratories Pty Ltd [2020] HCA 2; 270 CLR 494 the High Court (Kiefel CJ, Bell, Gageler, Keane and Gordon JJ) found that the Tribunal had erred in law but then continued, in language very similar to that used in the s 75(v) cases (at [40]): However, it does not follow that the Comptroller-General's appeal to the Federal Court from the decision of the Tribunal ought to have succeeded. That is because, for an error of law on the part of the Tribunal identified in an appeal on a question of law to the Federal Court to result in an order setting aside the decision of the Tribunal, the error must be shown to be material to the decision of the Tribunal in the sense that the decision which was in fact made by the Tribunal might have been different if the error of law had not occurred. 60 It is therefore necessary to address the broader problem that Ms Farrow-Smith's case in the Tribunal faced. If that problem was insurmountable, it would follow that the provision of a fair hearing on the issue of whether she had suffered mosquito bites at Yamba in March 2020 could not have made a difference to the outcome. 61 The starting point is that Ms Farrow-Smith was only entitled to compensation under the SRC Act if the relevant decision maker (the Tribunal) was satisfied that she had suffered an injury for the purposes of s 14. As a result, although it is usually unhelpful to refer to concepts of onus of proof in an administrative tribunal, the Tribunal needed to be persuaded that the relevant causal link between the condition that she suffered and her employment existed. 62 Ms Farrow-Smith's Statement of Facts, Issues and Contentions (SFIC) noted that she had lived in the Northern Rivers area for several decades without being infected with RRV and that her home "provided limited opportunities for virus carrying mosquitoes to infiltrate" (at [3.6]). The SFIC then contended (at [3.8]): It is not necessary to exclude every circumstance in which Ms Farrow Smith may have been bitten by mosquitoes. 63 It is fairly clear, therefore, that Ms Farrow-Smith was not seeking to persuade the Tribunal that the days on which she filmed flooding in the course of her employment were the only occasions on which she could potentially have been infected. In support of this position the SFIC cited South Australia v Roberts [2018] SASCFC 25; 130 SASR 274 at [122] (Parker J) (Roberts). 64 The respondent in Roberts was required to spend time in Oodnadatta (which is in a remote area of South Australia) for the purpose of her employment and stayed in accommodation arranged by her employer. The accommodation had inadequate insect screens and was so hot that the respondent needed to open the windows. She sustained mosquito bites. Soon afterwards she was diagnosed with an illness that was either reactive arthritis or inflammatory polyarthritis. There was a finding of fact that the condition was highly likely to have been caused by a mosquito bite, and there was a strong temporal association between the bites suffered at Oodnadatta and the onset of symptoms. The relevant legislation defined the term "injury" to include a "disease" and provided for compensation for an injury if it "arises from employment". It was further provided that an injury "arises from employment" if "the injury arises out of or in the course of employment and the employment was a significant contributing cause of the injury" (emphasis added). 65 Roberts came before the Full Court of the Supreme Court of South Australia as an appeal on a question of law from the South Australian Employment Tribunal. The issues in the appeal concerned whether the tribunal had properly applied the statutory test in circumstances where the relevant injury occurred while the respondent was in the place where the bites occurred as a result of her employment albeit not performing work at the time. Before the Tribunal in this case, Ms Farrow-Smith relied on the following statement by Parker J (with whom Blue J agreed) at [122]: As this is an appeal on a question of law, the finding that the Full Bench correctly applied the statute is enough to decide the matter. Nevertheless, I take the opportunity to note that if this appeal had extended to questions of fact, I would have concluded that the Deputy President did not err in concluding that the respondent's employment was a significant contributing cause of her injury. The medical evidence establishes that the respondent's illness was caused by mosquito bites. Those bites occurred because she was housed in unsatisfactory accommodation in an extremely remote location that was arranged or paid for by her employer. She was present in that location for the sole purpose of carrying out her duties as an employee. In those circumstances, whether or not she might have been bitten by disease carrying mosquitoes at her home or workplace in Adelaide is not to the point. 66 This, with respect, does not assist in the present case. Apart from the statement being clearly obiter, it addressed a situation in which the mosquito bites that caused the respondent's illness ("those bites") were found or assumed to have been sustained in the accommodation arranged by her employer. In contrast, in the present case the key issue of fact was whether the Tribunal should be satisfied that the bites suffered by Ms Farrow-Smith in the course of her employment were the bites that infected her with RRV. 67 The critical words of s 5B(1) of the SRC Act ("that was contributed to, to a significant degree, by the employee's employment") are words that, given their ordinary meaning, refer to a causal link that exists in fact. There are many decisions of this Court and the Tribunal considering how close that causal link needs to be in order to satisfy the description "contributed to, to a significant degree". All of these (so far as I have been able to ascertain) proceed on the basis that a causal link needs to exist in fact for the condition suffered by an employee to constitute a "disease" as defined. In Comcare v Canute [2005] FCAFC 262; 148 FCR 232 at [63] (Canute), French and Stone JJ said (in relation to a predecessor of s 5B which only required contribution "in a material degree") that "a causal connection is always necessary between the employment and the contraction of the disease". (Canute was overturned on appeal (Canute v Comcare [2006] HCA 47; 226 CLR 535) but not on this point.) More recently, in Comcare v Martin [2016] HCA 43; 258 CLR 467, French CJ, Bell, Gageler, Keane and Nettle JJ construed the phrase "as a result of reasonable administrative action" in s 5A(1) as taking its content, in the case of a disease, from s 5B(1). The result was that "an employee has suffered a disease 'as a result of' administrative action if the administrative action is a cause in fact of the disease which the employee has suffered" (at [45]). It is implicit in this reasoning that s 5B(1) requires causation in fact. 68 As a result, it was not sufficient for Ms Farrow-Smith to show that RRV is carried by mosquitoes and she was bitten by mosquitoes on a particular day while performing her duties. It was not in doubt that mosquitoes were common in the Northern Rivers region and RRV was endemic. The Tribunal needed to be convinced that Ms Farrow-Smith's infection resulted from bites that she received in the course of her employment (or in circumstances connected with it) and not from a bite received in some unrelated setting. As noted earlier, Ms Farrow-Smith gave evidence about her home, directed at showing that steps had been taken to minimise the presence of mosquitoes there. She also gave evidence that she did not recall being bitten by anything in March 2020 and spent most of her time at home. The Tribunal did not find this helpful, noting that it had "no detailed information about the daily movements of the Applicant" (at [267]) and emphasising evidence of Dr Navin that "wherever one may be, and whatever time of the day it might be and wherever a person may be located, a mosquito, if it has close access, will feed" (at [268]). Given these findings and the state of the underlying evidence it appears that, even without the inference drawn from Dr Hannah's notes that she suffered a significant number of bites while at Yamba, Ms Farrow-Smith would have had significant difficulty persuading the Tribunal that her RRV infection should be attributed to the mosquito bites she sustained while filming. 69 I am not satisfied, however, that this difficulty was insurmountable. Comcare did not submit that it was necessarily a complete barrier to success for Ms Farrow-Smith. A case concerning the causes of a disease will rarely be able to be proved with certainty by eliminating all possible origins but one. Hence, in Coward v Military Compensation and Rehabilitation Service [2006] FCA 840; 153 FCR 535 at [34] Cowdroy J said: This finding [that there was no evidence other than timing linking the applicant's condition with his employment] does not mean that a person claiming compensation would always need to demonstrate the exact event which caused an illness to occur, or be able to show with certainty which activity was the cause. If, for example the applicant in this case had demonstrated that an epidemic of gastro-enteric infections had been experienced at the barracks during the four-month period preceding the onset of his symptoms, the Tribunal may have been able to conclude that it was most likely to have been a gastro-enteric infection contracted in the course of employment which was the cause of his reactive arthritis. 70 In the present case, had Ms Farrow-Smith's evidence been accepted, it would have been open to the Tribunal to find that the multiple mosquito bites she received while filming in the course of her employment were most likely to have been the source of the RRV infection. Such a finding would be at least logically possible if the Tribunal accepted that apart from this event Ms Farrow-Smith was rarely if ever bitten by mosquitoes. The expert evidence as construed by the Tribunal weighed heavily against, but did not entirely exclude, such a finding. As noted earlier, the Tribunal was somewhat dismissive of Ms Farrow-Smith's evidence in this regard. However, there is a realistic prospect that the case could have taken on a different complexion if Ms Farrow-Smith had been given a proper opportunity to confront the suggestion that she had been "smashed" by mosquitoes at Yamba (and that her evidence was therefore incorrect). In Nathanson v Minister for Home Affairs [2022] HCA 26; 276 CLR 80 at [33] Kiefel CJ, Keane and Gleeson JJ observed that the standard of "reasonable conjecture" (the test for materiality in s 75(v) contexts) is "undemanding" and usually satisfied if a party is denied an opportunity to present evidence on a relevant issue. 71 While Ms Farrow-Smith's case in the Tribunal clearly faced significant difficulties, it was not bound to fail. The failure to afford her procedural fairness was therefore material. It requires that the decision of the Tribunal be set aside.

Persistence of symptoms 72 Ms Farrow-Smith's submissions raise a further Browne v Dunn issue, although the point is put primarily as the wrongful rejection of a submission by the Tribunal. The submission (made in the written submissions in reply and rejected by the Tribunal at [63]-[64]) was that Comcare had not challenged Ms Farrow-Smith's account of debilitating symptoms from late February 2020 onwards and was precluded from submitting that her evidence or that of her partner should be rejected. The submission was much too broad in so far as it sought to prevent any questioning of Ms Farrow-Smith's evidence. However, as to whether Ms Farrow-Smith's symptoms had persisted from late February 2020 until she saw Dr Hannah in April, the approach of cross-examining Ms Farrow-Smith through the notes of Dr Hannah, instead of asking her directly about her symptoms, created problems. It meant that she was being questioned about what she said or did not say to Dr Hannah rather than directly or clearly challenged on her evidence in chief. In this respect, also, Ms Farrow-Smith's partner (who corroborated her evidence) was not challenged at all. 73 Despite this, the Tribunal appears to have rejected Ms Farrow-Smith's account of the continuation of her symptoms. I say "appears" because the reasons on this point are less than clear. Having referred to this part of Ms Farrow-Smith's account, the Tribunal observed at [221] that "the problem" was that it was "not reflected" in the notes of Dr Hannah. No express finding was made. However, at [263] the Tribunal said that it "proceeds on the basis" that Ms Farrow-Smith was unwell from 26-28 February 2020 (which seems to exclude the acceptance of symptoms thereafter); at [321] (having set out the things that it accepted) it observed that there was "no medical evidence before us as to the duration of the Applicant's illness"; and at [341(b)] (which is quoted above at [43]), among what were described as findings, it observed that there was no evidence other than that of Mr D'errey that "would support" the proposition that Ms Farrow-Smith was unwell throughout March 2020. I read these passages as having rejected the evidence of Ms Farrow-Smith and her partner that her symptoms persisted through March 2020. 74 This was a further denial of procedural fairness. It was clearly material in the sense discussed above. Acceptance of this aspect of Ms Farrow-Smith's evidence would have materially strengthened the argument that the condition she was suffering in April 2020 (which was undoubtedly caused by RRV) had the same origin as the illness that first affected her in late February. This is an additional reason why the decision of the Tribunal should be set aside.

Proper evidentiary basis 75 The remaining submissions for Ms Farrow-Smith lead to a proposition that the Tribunal's decision lacked "any proper evidentiary basis". The argument has the following elements. (a) Criticisms are made of the Tribunal for having used the (unverified) clinical notes of Dr Hannah as the basis for rejecting evidence of Ms Farrow-Smith. (b) The Tribunal's observation that it had no detailed information about Ms Farrow-Smith's daily movements is said to be "groundless and demonstrably wrong". (c) The Tribunal is said to have misstated and misunderstood Dr Gover's evidence and his report of 7 July 2020 and to have been wrong in concluding that his evidence "refutes" Ms Farrow-Smith's case that she was not bitten by mosquitoes at Yamba. (d) Professor Korman and Dr Navin are criticised for relying on the results of Ms Farrow-Smith's blood tests to estimate the time of infection, paying no regard to her reports of when she was bitten and the timing of her symptoms. Issue is taken with some of their analysis of the scientific literature. 76 These criticisms attempt to reagitate the merits and do not raise any issue of law. Assessment of the evidence and finding facts were tasks for the Tribunal. While the use of clinical notes (whose author was not called) to make findings about antecedent events (that the author did not witness) is disquieting, it is not such a departure from rational fact finding as to found a conclusion that the Tribunal misunderstood its statutory task. With those findings made, the course of Ms Farrow-Smith's exposure to RRV and her symptoms aligned with the expert evidence about the blood test results to point to a strong likelihood of the infection having occurred while Ms Farrow-Smith was on leave.

Ground (d): "Disease" vs "Injury (other than a disease)" 77 In her Statement of Facts, Issues and Contentions and her written submissions before the Tribunal, Ms Farrow-Smith sought to characterise her ailment as an "injury (other than a disease)" within the meaning of s 5A(1)(b) of the SRC Act. The Tribunal, however, appears to have approached the case on the footing that RRV was a "disease". This appears from the conclusion at [345] (quoted at [43] above), which is in terms that reflect s 5B(1). 78 It is submitted for Ms Farrow-Smith that in this respect the Tribunal failed to grapple with the submission that she made and erred in law. However, senior counsel did not develop the submission orally and appeared to accept that it would have no effect on the outcome. 79 The argument leads nowhere. It can be accepted that a mosquito bite is "a physical or mental injury" which, if incurred "in the course of" the employee's employment, is in principle compensable. On the facts as found by the Tribunal, Ms Farrow-Smith suffered several mosquito bites in the course of her employment. However, liability to pay compensation for an injury arises only to the extent (relevantly here) that it results in incapacity for work. Thus, to establish liability on this approach, Ms Farrow-Smith would need to establish that it was a mosquito bite received in the course of employment (and not a bite received at some other time) that caused her to contract RRV and therefore to be incapacitated. This was the issue on which she failed to persuade the Tribunal. 80 The distinction between the way the causal requirements are expressed (an injury "arising out of, or in the course of" employment vs a disease "contributed to" by that employment) is therefore irrelevant in the present case. If Ms Farrow-Smith contracted RRV from being bitten while filming flooding for her employer, she succeeds on either test. If it is not established that she was infected by a bite sustained on that occasion, she fails on either test. 81 In any event, the structure of s 5A(1) weighs against treating a viral infection (said to have been contracted as a result of something happening in the course of employment) as the consequence of an "injury (other than a disease)" rather than as a "disease". The subsection posits these as alternatives. It directs attention first to a "disease" and then to an "injury (other than a disease)". The physically debilitating consequences of infection with RRV clearly constitute an "ailment". If the issue mattered, I would hold that the Tribunal did not err by framing the issue as whether an "ailment" suffered by Ms Farrow-Smith was "contributed to, to a significant degree, by her employment".

Disposition 82 The appeal must be allowed and the decision of the Tribunal set aside. 83 Despite the submissions advanced for Ms Farrow-Smith, this is not an appropriate case for the Court to make findings of fact under s 44(7) of the AAT Act so as to dispose of the matter without a further hearing. The finding sought (to the effect that Ms Farrow-Smith was infected by RRV as a consequence of an injury suffered in the course of her employment) would, apart from anything else, be inconsistent with findings of fact made by the Tribunal (cf s 44(7)(a)). These findings have to some extent been made in breach of the principles of procedural fairness, but in my view it does not follow that they can be ignored on the footing that they are "the result of an error of law". The Tribunal, as I have noted above, was not bound to accept all of Ms Farrow-Smith's evidence. It would therefore be inappropriate to decide the case on the footing that her evidence has been accepted. Resolution of the factual issues in the case requires an assessment of the credibility of Ms Farrow-Smith's evidence, a nuanced understanding of the expert evidence and a weighing of both. It should be done by the Tribunal. 84 The matter will therefore be remitted to the Tribunal for consideration according to law. There is no reason why the costs of the appeal should not follow the event. For the reasons set out in Norton v Comcare [2000] FCA 1446 (Drummond J), any order in relation to the costs of the proceeding in the Tribunal must await the outcome of the hearing on remitter. I certify that the preceding eighty-four (84) numbered paragraphs are a true copy of the Reasons for Judgment of the Honourable Justice Kennett.