Workers Compensation - Entitlement to compensation - Injury, disease or disability - Disease - Aggravation or acceleration of pre-existing disease or condition - General principles - Causation - Employment major or most significant contributing factor to aggravation, acceleration, exacerbation or deterioration of pre-existing disease.

Workers Rehabilitation and Compensation Act 1988 (Tas), ss 3, 25, 81A.

Long v Kmart Australia Ltd [2016] TASSC 6, 25 Tas R 237, applied.

Workers Compensation - Liability to pay compensation - Liability of employer - Other cases - Reasonably arguable case - Liability to pay compensation - Dependent on the existence of requisite causal relationship between employment and injury.

St Helens Oysters Pty Ltd v Coatsworth [2007] TASSC 90, 17 Tas R 43; Vos Construction & Joinery Pty Ltd v Norton Smith [2016] TASSC 38, 26 Tas R 448; Bradshaw v Tasmania Networks Pty Ltd [2019] TASSC 41; Bradshaw v Tasmania Networks Pty Ltd [2020] TASFC 2, applied.

Workers Compensation - Proceedings to obtain compensation - Preliminary requirements - Interim payments - Reasonably arguable case for employer not established - No error established.

Workers Rehabilitation and Compensation Act 1988 (Tas), s 81A.

Protective Security Pty Ltd v Bedelph [2004] TASSC 128, 13 Tas R 354; St Helens Oysters Pty Ltd v Coatsworth [2007] TASSC 90, 17 Tas R 43; Burrage v Rural Press Limited [2013] TASSC 43, applied.

Judgment Number: [2021] TASSC 22

1. On 12 August 2020 the Workers Compensation and Rehabilitation Tribunal, constituted by Chief Commissioner Clues, determined a reference brought by the appellant under s 81A of the Workers Rehabilitation and Compensation Act 1988 (the Act) concerning a claim made by the respondent for weekly payments and other benefits under the Act.
2. The Tribunal determined that the appellant had not established that there was a reasonably arguable case to dispute liability for a claim and ordered that the appellant make weekly payments and pay benefits from 14 April 2020: Tassal Operations Pty Ltd v L [2020] TASWRCT 28. This is an appeal against that order. Shortly stated, the issue before the Tribunal was whether it was reasonably arguable that the respondent did not suffer an injury, as defined in s 3 of the Act, with the necessary causal relationship to his employment so as to enable a claim for compensation under s 25.
3. The appellant contends that the Tribunal erred. The substance of the appellant's contention is that the Tribunal should have determined that a reasonably arguable case existed concerning the liability of the appellant to pay compensation to the respondent. For the following reasons, none of the grounds of appeal are established.

1. The liability of an employer to pay compensation arises under s 25(1) of the Act. That section provides as follows:

"25 Liability of employers to compensate workers for injuries

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

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

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

1. The terms "injury" and "disease" are defined in the Act, s 3:

"'disease' means any ailment, disorder, defect, or morbid condition, whether of sudden or gradual development;

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

"(2A) For the purposes of this Act, employment contributed to a disease to a substantial degree only if it is the major or most significant factor."

1. The role of s 81A in the scheme created by the Act, and the principles to be applied, are not in contention. They have been stated in many cases and were summarised by Brett J in Bradshaw v Tasmania Networks Pty Ltd [2019] TASSC 41 at [5]- [7]:

"[5] The scheme implemented by s 81A is that an employer who disputes liability in respect of a claim for compensation, must serve a notice of dispute on the worker, which informs the worker of the reasons for the dispute, and must then refer the matter to the Tribunal. The employer must do this within 84 days of receiving the claim. If this is not done within that time, the employer will be taken to have accepted liability in respect of the claim (s 81AB). Upon referral, the Tribunal must order the employer to make the specified payments unless it considers that 'a reasonably arguable case exists concerning the liability of the employer to pay compensation', in which case it shall determine that compensation is not to be paid by the employer. The Act therefore establishes 'a relatively speedy process for assessing whether an employer, who wishes to dispute liability to pay weekly compensation, has a reasonably arguable case in that regard ...' (per Crawford J (as he then was) in Walker v J and A Freeman Building Services [2006] TASSC 90, 16 Tas R 87). This process is consistent with the beneficial nature of the legislation.

[6] It is well established that the employer bears the onus of demonstrating the existence of a reasonably arguable case that compensation is not payable: Skill Group Limited v Anning [2015] TASSC 18, 23 Tas R 463; Lamont v M R V Supermarkets Pty Ltd [2016] TASSC 16, 24 Tas R 234. The section requires the employer to compile and deliver evidentiary material: s 81A(2)(b). The test to be applied by the Tribunal on the referral has been described in the following terms:

'a reasonably arguable case will exist concerning the liability of an employer to pay a worker if it is reasonably arguable on the material available in relation to the claim or identified deficiencies or weaknesses in the claim that, following a contested hearing it may be rejected.'

St Helens Oysters Pty Ltd v Coatsworth [2007] TASSC 90, 17 Tas R 43.

[7] It is not sufficient for the employer to indicate that it simply wishes to put the worker to proof: Vos Construction & Joinery Pty Ltd v Norton-Smith [2016] TASSC 38, per Pearce J at [5]."

1. The Act does not require that the employer's case about liability be strong or compelling, but the case that the claim may ultimately be rejected must be reasonably arguable. The employer is not required to prove that there was no liability under s 25(1) of the Act, but rather that there existed, on the evidentiary material before the Tribunal, a reasonable chance that the worker would be unable to discharge the onus of proof that would rest on him by operation of s 49(2)(a) at a final hearing.

1. For convenience and ease of understanding I will refer in these reasons to the appellant as the employer and the respondent as the worker.
2. The employer is an aquaculture company. The worker had been employed since 2012 and was an offshore harvester. His duties included tying and untying fish harvest vessels, pulling seines (a type of net), and harvesting fish. His claim form was lodged on 28 April 2020. It referred to a "strain" injury to his right shoulder said to have occurred more than two months earlier on 20 February 2020. As to the details of what happened he wrote: "when packing up the seine I lifted a weight to unhook it and felt a twing [sic] in my right shoulder". The claim form was accompanied by a certificate from the worker's general practitioner, Dr Saul. According to the certificate, the worker presented to Dr Saul on 24 March 2020 with "increased pain R side of neck with numbness some weakness and wasting scapular region." The certificate referred to an incident mistakenly said to have occurred on 27 February 2020. Dr Saul wrote that the injury occurred "late February lifting heavy weight 60 to 70 kg sudden pain in neck and with lifting right arm". The worker was certified as fit for light duties from 26 March 2020 to 10 April 2020 and referred for physiotherapy.
3. At Dr Saul's request an MRI of the worker's cervical spine was performed on 24 March 2020. The radiologist's report of the MRI concluded:

"Multilevel degenerative disc osteophyte complex is within the cervical spine. There are broad-based posterior disc osteophyte complex is from C3-4 to C6-7 resulting in severe bilateral C3-4, right C4-5, bilateral C5-6 and bilateral C6-7 neural exit foraminal stenosis with probable impingement of the bilateral C4, right C5, bilateral C6 and bilateral C7 nerve roots respectively."

1. Dr Saul referred the worker to the Tasmanian Spine Service. Dr Nevin Colgrave, a medical practitioner from that service, saw the worker on 7 April 2020. Dr Colgrave's report bearing the same date indicates that he had the MRI result available to him. The report was before the Tribunal. Dr Colgrave described a history given that the worker had:

"...developed right upper limb weakness after a period of heavy lifting at work about three weeks ago. Over a period of several days he noted a marked decrease in power in his shoulder and elbow. He has had some mild associated right neck pain."

1. Dr Colgrave's report continued that "given the lack of improvement in his symptoms over the past three weeks surgical intervention in the form of a two level [anterior cervical discectomy and fusion] will certainly need to be considered".
2. The next medical certificate was written by Dr Saul after having received Dr Colgrave's report and following an examination of the worker on 23 April 2020. The symptoms were described as "wasting significant reduction in strength right arm" with a diagnosis "Disc Lesion C4/5 with nerve root compression." He remained fit for light duties but had been referred "for surgery ...".
3. In a letter to the employer's insurer dated 7 May 2020 Dr Saul reported that when he first saw the worker, the worker "described pain in the right side of the neck with subsequent numbness and weakness of the right arm." By that time Dr Saul also had the report of a CT scan of the worker's cervical spine performed on 20 April 2020 available to him. Dr Saul indicated that he had been advised by a surgeon, Mr Nova Thani, who recommended urgent surgery. Dr Saul continued:

"In answer to your more specific questions this man has had an acute injury but also has existing severe osteoarthritic disease. Mr Thani has not made comment on the mechanism of injury except to say it began after a lifting incident at work.

As to the most substantial cause of this man's need for surgery this is most difficult to say. He has extensive underlying osteoarthritic changes as per his MRI scans. Mr Lese has a long background of heavy manual work with Tassal and other employers as well as rugby as a recreational past time. However he has had no neck or shoulder symptoms in the past nor has he had any sick leave to his knowledge in relation to this Osteoarthritis prior to his current injury. Given his excellent health and fitness to date it is my opinion that the work incident is the most significant factor contributing to his surgical need."

1. The employer's insurer sought a report from a neurosurgeon, Mr Peter Dohrmann. The report is dated 15 May 2020. Mr Dohrmann was given copies of the certificates and reports to which I have referred. He interviewed and examined the worker on 11 May 2020 remotely by means of a telehealth assessment. Mr Dohrmann reported the worker having informed him that he was performing his normal duties on a boat which involved lifting a weight to untie a connection to a fishing net when he "felt an immediate feeling of something cold on the right side of his neck". Mr Dohrmann reported the worker as having told him that he drove across Tasmania to the west coast the next day but found it difficult to work because he had "developed significant weakness in his right arm". He said he reported to his manager, and in turn to a safety officer, before being referred to a company physiotherapist. He complained that his symptoms had not changed during the ten weeks since the end of February. The symptoms primarily included severe weakness of his right arm and shoulder. Mr Dohrmann diagnosed the worker as suffering from "right C5 radiculopathy due to compression of the right C5 nerve root in the right C4/5 exit foramen" and concluded that the condition resulted from the incident at work in February 2020, which caused "an aggravation of previously asymptomatic degenerative cervical spondylosis".
2. The employer's insurer sought a further report from Mr Dohrmann. He was asked to review his opinion assuming the possibility of different facts recited in emails dated 22 May 2020, one from Peter Fussell, the worker's Tassal manager and another from John Edwards of Tassal. The questions Mr Dohrmann was asked and his responses were:

"Given that Mr Lese reports he felt a 'cold feeling' on the alleged date of injury 20/2/2020, and then worked normally up until the 16/3/2020 which is when he reported an event 20/2/2020, would his injury/condition be expected to normally result in a slow deterioration without need to report issues over a 25 day period?

It is conceivable that Mr Lese developed a 'cold feeling' on 20.02.2020 as a result of injury at that time which then slowly deteriorated to a point where he felt it necessary to report the event some time later.

However, as noted above, the discrepancy between the history I obtained and the known facts is sufficiently great that it casts into doubt my previous conclusion that there was a definite relationship between his employment and his neck condition.

And, if progression of symptoms can occur in a slow manner, can it be stated with any medical certainty that the event at work was the substantial cause of the aggravation on the underlying condition given that 17 days were off shift and 8 days were on shift?

Medical opinion always rests on the assumption that the history that has been obtained is accurate and that the physical findings are valid. Given the information that you have provided, I can now no longer be certain that the history I obtained is sufficiently accurate to draw medical conclusions with certainty. Therefore, at least for the time being, I cannot be certain that the event at work on 20.02.2020 was the substantial cause of the aggravation in Mr Lese' underlying neck condition, noting that he had 17 days off shift between the onset of symptoms and his reporting of those symptoms."

1. Subsequently, witness statements were prepared for Mr Fussell dated 7 July and another Tassal employee, Shaun Flannigan, dated 17 July 2020. Both statements were before the Tribunal. They contained assertions capable of establishing that:
   • the worker worked a 7 day on, 7 day off roster;
   • he was due to work between 20 and 26 February 2020;
   • he worked in Dover on 20 February 2020 but went home during the course of 21 February 2020 after reporting that he needed to look after his children because his wife had been admitted to hospital;
   • he next returned to work in Strahan between 5 March 2020, having travelled on 4 March, until 10 March 2020;
   • while in Strahan, on the 5 to 10 March swing shift, he told Mr Flannigan that his shoulder was sore, but he was hoping it would "come good';
   • in a separate conversation during the same shift he told Mr Flannigan that he had moved a bullet weight and "that's when he felt something", although he said nothing to indicate that he could not continue with his normal duties, and the nature of his complaint did not prompt Mr Flannigan to complete an incident report or an "aches and pains early intervention report";
   • he was next due to work in Strahan on 19 March 2020 but did not do so;
   • he first reported his injury to Mr Fussell on 16 March 2020, when he told him that his shoulder "had been bugging him for a while";
   • the worker was familiar with the company policy which required reporting of work injuries.
2. The remaining material before the Tribunal was in the form of a document prepared by the worker which contained his account. It included statements to the effect that:
   • he injured his shoulder on 20 February 2020 "while trying to lift the weight attached to the seine net to unhook it getting ready for pack up". He felt a "cold pinch onto his right shoulder";
   • he worked again on 21 February but left work on that day when his wife was admitted to hospital, and he stayed home between 22 February and 3 March to look after her;
   • while at home during that period his shoulder caused him pain;
   • he worked between 5 and 9 March in Strahan but was only able to manage with the assistance of a co-employee, whom he told about his shoulder injury;
   • the pain did not subside between 11 March and 16 March when he informed Mr Fussell and reported the injury.

The s 81A application and the Tribunal determination

1. The employer referred the claim to the Tribunal under s 81A on 20 July 2020. The referral contained four grounds of dispute but only two, grounds 3 and 4, are relevant to this appeal. Those grounds assert the employer's contention:
   • by ground 3, that "if the worker is suffering from an injury which is a disease, then the worker's employment did not contribute to a substantial degree in accordance with s 25(1)(b) of the Act in that it wasn't the major or most significant factor"; and
   • by ground 4, that "if the worker is suffering from an injury which is a recurrence, aggravation, acceleration, exacerbation or deterioration of any pre-existing injury or disease as prescribed in s 3(1) of the Act, then the worker's employment was not the major or most significant contributing factor to that recurrence, aggravation, acceleration, exacerbation or deterioration".
2. The Chief Commissioner, after reviewing the evidence, concluded that the worker "suffered an injury that is a disease and further that he suffered an aggravation of his underlying disease to which his employment was the major or most significant contributing factor". The Chief Commissioner found, with respect to the relevant grounds of the referral, that those grounds were "not reasonably arguable". It is the reasoning to that conclusion which is challenged in this appeal.
3. The Chief Commissioner first found it to be clear that the worker did not, on 20 February 2020, suffer an injury "in the primary sense". However, she continued that:

"In Mr Dohrmann's first report he states that in his opinion the worker suffered 'an aggravation of previously asymptomatic degenerative cervical spondylosis.' This condition comes within the definition of disease and would constitute injury pursuant to s 25(1)(b)."

1. The Chief Commissioner found that, according to the operation of s 3(5), the injury was deemed to have occurred on 26 March 2020, which was the date on which the worker was first "certified to be incapacitated". The material before the Commissioner made clear that 26 March 2020 was the first day of the worker's next shift following his appointment with Dr Saul. He had not worked since 10 March 2020. The Commissioner's reasoning to the conclusion that the worker suffered an injury is to be found in her reasons at [26]-[29]:

"26 In this case, the extended definition of injury must be considered. The evidence is that the worker suffered pain in his right shoulder as a result of an incident that occurred at work on 20 February 2020. That pain progressed to the point where he was certified as incapacitated for work from 26 March 2020. That incapacity arose from an aggravation of the worker's underlying disease (cervical spondylosis).

27 The only reasonable conclusion (in my opinion) available on the evidence, including Mr Dohrmann's reports, is that the incapacity the worker suffered on 26 March 2020 resulted from his experience of symptoms at work on 20 February 2020 and those symptoms constituted an aggravation of the worker's underlying cervical spondylosis.

28 lt of the incident that occurred at work on 20 February 2020 (see Long v Kmart Australia Limited [2016] TASSC 6).

29 Having found that the worker's incapacity arose from an aggravation of his underlying disease, he has suffered an injury within s25(1). However, liability on the part of the employer to pay compensation for that injury depends upon the existence of the requisite causal relationship between the employment and the injury."

1. The Commissioner then addressed the issue of causation. She recited and reviewed the material which was before her. She referred to Mr Dohrmann's opinion, expressed in his first report, that the worker "described the onset of right shoulder and arm weakness from the outset and I do not consider there was any break in the causal connection to the work injury". She found, at [36] of her reasons, that "there was no evidence at the hearing to support a break in the causal chain". For reasons which she gave, the Commissioner was unpersuaded that the expression of uncertainty in Mr Dohrmann's second report that the event at work on 20 February 2020 was the substantial cause of the aggravation in Mr Lese's underlying neck condition should alter her conclusion.

1. The first ground of appeal asserts that the Chief Commissioner erred in law "when a proper evaluation of the appellant's evidentiary material, having regard to the test to be applied in the proceedings before her, called for a determination contrary to that of the Chief Commissioner".
2. Section 63 provides for a right of appeal to this Court if any party to a proceeding before the Tribunal is aggrieved by a determination or order of the Tribunal, but the right is confined to appeals "in point of law". This ground can only succeed if the material before the learned Commissioner necessarily led to a conclusion that a reasonably arguable case did exist. Only then would the Commissioner's determination and order amount to error in point of law: St Helens Oysters Pty Ltd v Coatsworth [2007] TASSC 90, 17 Tas R 43 at [15]; Protective Security Pty Ltd v Bedelph [2004] TASSC 128, 13 Tas R 354 per Crawford J at [22]-[28]. If, on the material before the Tribunal, reasonable minds could differ as to the existence of an arguable case, a conclusion one way or the other could not, of itself, be regarded as indicating any error of law. If the conclusion reached by the Commissioner was reasonably open, then an error in point of law has not been established: Burrage v Rural Press Limited [2013] TASSC 43.
3. It is first necessary to recall the bases upon which liability might be established under the Act. Cases in which the principles have been explained include Long v Kmart Australia Ltd [2016] TASSC 6, 25 Tas R 237, Vos Construction & Joinery Pty Ltd v Norton-Smith [2016] TASSC 38, 26 Tas R 448 and Bradshaw v Tasmania Networks Pty Ltd [2019] TASSC 41, upheld on appeal in Bradshaw v Tasmania Networks Pty Ltd [2019] TASFC 2.
4. The Act, s 25(a), deals with what is commonly referred to as an injury in the primary sense, that is, an injury which is not a disease. The meaning of the term "injury" in that sense was considered by the High Court in Military Rehabilitation and Compensation Commission v May [2016] HCA 19, 257 CLR 468. At [52] the majority applied the reasoning of Gleeson CJ and Kirby J in Kennedy Cleaning Services Pty Ltd v Petkoska [2000] HCA 45, 200 CLR 286 and stated that whether there is such an injury will generally be determined by asking whether a worker has suffered something that can be described as a sudden and ascertainable or dramatic physiological change or disturbance of the normal physiological state. In Kennedy Cleaning v Petkoska, at 300 [39], Gleeson CJ and Kirby J explained:

"[C]onsideration [must] be given to the precise evidence, on a fact by fact basis, concerning the nature and incidents of the physiological change accepted at trial. If this evidence amounts, relevantly, to something that can be described as a sudden and ascertainable or dramatic physiological change or disturbance of the normal physiological state, it may qualify for characterisation as an 'injury' in the primary sense of that word."

1. In this case, the Tribunal determined that there was no evidence of an injury in that primary sense. The material before the Tribunal, including the reports from Mr Dohrmann and Dr Saul, and the MRI and CT scan reports, did however make clear that the worker suffered from a disease described by Mr Dohrmann as degenerative cervical spondylosis. That condition fell within the definition of "disease", and hence constitutes an injury pursuant to s 25(1)(b). However, there was no material before the Tribunal to suggest that the worker's employment contributed to the appellant suffering that injury to a substantial degree, or to any degree, or that the injury had resulted in incapacity, and thus the injury was not compensable. Mr Dohrmann referred to the condition as "previously asymptomatic."
2. The worker's claimed entitlement to compensation thus depended on whether what he experienced on 20 February 2020 amounted to an aggravation, acceleration, exacerbation or deterioration of his pre-existing disease within par (b) of the definition of injury, and which resulted in incapacity. I will refer to the five terms used in the definition by the shorthand term "aggravation", although the words used in par (b) are not synonymous, have different shades of meaning, and are not mutually exclusive: Federal Broom Co Pty Limited v Semlitch [1964] HCA 34; (1964) 110 CLR 626 per Kitto J at 634; Long v Kmart Australia Ltd at [47]. As Porter J pointed out in the Full Court in Bradshaw at [66], the term "acceleration" may be best suited to progressive conditions. If a worker is suffering from a pre-existing disease, irrespective of how it was caused or contracted, and if the employment contributed to an aggravation to the requisite degree, then there is an injury within the operation of the Act. For the aggravation to be compensable, it must be established that the worker's employment contributed to it to a substantial degree, which means that the employment must have been the major or most significant factor: s 3(2A).
3. The interrelationship between s 25(1)(b) and the extended definition of "injury" in s 3 was considered by Porter J in Long v Kmart Australia Ltd. The causative requirement in s 25(1)(b) relates to the aggravation or exacerbation of the underlying disease, not the development of the disease itself. The terms recurrence, aggravation, acceleration, exacerbation and deterioration, when applied to a pre-existing injury, mean something which results in an increase or intensification of symptoms: Federal Broom Co Pty Limited v Semlitch (above) per Kitto J at 634. It follows that the questions to be addressed were whether the worker had a pre-existing disease, whether there had been an aggravation or acceleration of that disease, and whether the employment was the major or most significant contributing factor to that aggravation or acceleration. In my opinion there was no reasonable argument about the first two issues. The evidence that the worker had a pre-existing disease and was experiencing new symptoms including marked weakness in his right shoulder and arm, was overwhelming. Thus, the question before the Tribunal distilled to whether there was a reasonable argument that the worker's employment was not the major or most significant contributing factor to that aggravation. There could also have been no reasonable argument that the aggravation occurred either on 20 February 2020 or on some other day between then and 24 March 2020, when he saw Dr Saul. As part of that question, the Tribunal was required to consider whether the evidence permitted a reasonable argument that there were other possible causes of the worsening of the appellant's condition on and following 20 February 2020, other than his employment, which might qualify as the major or most significant factor. As was pointed out by Evans J in St Helens Oysters Pty Ltd v Coatsworth at [14]:

"... where there are a variety of potential causes for the condition, an employer may show a reasonably arguable case concerning liability by providing evidence of plausible potential causes that are inconsistent with liability."

1. In Mr Dohrmann's first report, his opinion was clear. Of course, he could not know whether the aggravation of the worker's condition arose from an incident he did not witness, but, in answer to questions asked by a representative of the employer's insurer, he concluded that:

"Noting that Mr Lese has significant multilevel cervical spondylosis on imaging, but also noting that this was previously free of any symptoms, I conclude that Mr Lese's current condition has arisen as a result of an aggravation of previously asymptomatic degenerative cervical spondylosis.

It is possible that Mr Lese may have been destined to develop acute right C5 radiculopathy even without an external contribution but this, in my view, is entirely speculative. On the basis of the clinical assessment, and assuming that the facts presented to me are correct I conclude that the external contribution at work in February 2020 was responsible for the development of the current symptomatic condition. In other words, I consider that it is highly unlikely that Mr Lese would find himself in his current predicament had this incident never occurred."

1. It can be seen from those passages that Mr Dohrmann's opinion was based on an assumption that something described by the worker as having occurred at his employment on 20 February 2020 was the external stimuli which resulted in the manifestation of harmful or painful symptoms: Cook v Midpart Pty Ltd [2008] NSWCA 151, 6 DDCR 316 per Allsop P at [44]. The fundamental proposition put by the employer to the Tribunal, and which forms the basis of this appeal, was that other material before the Tribunal compelled the conclusion that it was reasonably arguable that the worker's employment was not the major or most significant contributing factor to the aggravated disease. For example, the employer now points to the possibility of a natural progression of the disease, inconsistent with liability. As Porter J said in Long at [67]:

"In an appropriate case, the contribution of the employment to an aggravation will have to be taken into account, to the extent the evidence permits, the contribution of the natural progression of the disease to the worsening of the condition. But the worsening of the condition has to be distinguished from the end result; that is, the aggravated disease."

1. Similarly, in the Full Court in Bradshaw, Porter J stated at [67]-[68]:

"In an appropriate case, consideration must include the possible effect of the natural progression of a pre-existing condition and, to the extent the evidence permits, the contribution of the employment will have to take into account the contribution of the natural progression to the worsening of the condition. See also Vos Construction & Joinery Pty Ltd v Norton-Smith [2016] TASSC 38 at [25]-[26]. That appears to be relevant to the appellant's claim.

For the employment to be a contributing factor under par (b), there must be an incident or state of affairs to which the worker was exposed in the performance of their duty, and to which they would not otherwise have been exposed; some event or characteristic of the work or the conditions in which it was performed. In the case of an aggravation of a disease, the aggravation does not have to arise out of or in the course of the employment; there is no requirement for a temporal connection with the employment. Where one of the outcomes or consequences exists, the question is simply whether the employment has the requisite degree of causal connection."

1. The relevant enquiry is a factual one. For that reason, the employer points to factual issues which, it contends, form the basis of the uncertainty expressed by Mr Dohrmann in his second report about the connection between the worsening of the worker's condition and the employment. The facts which were said to have prompted the uncertainty were contained in two emails not in the material before the Tribunal. Mr Dohrmann referred to "known facts" but did not specify what it was he had been told which caused him to alter his opinion. It was a matter which caused the Chief Commissioner some concern. It was one of the things which led her to state, in her reasons, that she gave Mr Dohrmann's second report no weight. That statement should not be interpreted as the Commissioner disregarding the report. It is obvious from her reasons that she gave the contents of the report, and the basis of it, careful consideration.
2. In his second report, Mr Dohrmann referred to "records" given to him by the insurer following his first report which suggested "that the history provided to [him] by Mr Lese differs significantly from what has been recorded by his employer". Mr Dohrmann repeated his understanding, based on the history first given to him by the worker, that "he developed symptoms in late February 2020 while at work and travelled across Tasmania the following day to continue his work", and that "this cannot be correct as there was clearly a long delay between the first symptoms and the reporting of these symptoms and the reporting of these symptoms to the employer." Mr Dohrmann suggested that one way to resolve the discrepancy was for him to re-interview the worker. In his report there was no explanation of how and why the correction of his mistaken assumption that the worker had driven across Tasmania on 21 February 2020 caused him to alter his opinion. Nor did Mr Dohrmann explain why it was that a failure by the worker to report symptoms to the employer until 16 March 2020, if that were true, led to a change in his opinion. In the letter seeking the second report Mr Dohrmann was informed by the insurer that the worker had, after experiencing a cold feeling on 20 February 2020, "worked normally until 16 March 2020". Mr Dohrmann was also informed that the worker had "17 days off shift" between the offset of symptoms and his reporting of those symptoms. No explanation of why those facts, if true, caused a change in his opinion was offered. In my view, the insurer's assertions that the worker "worked normally" until 16 March, but had "17 days off shift" were also potentially confusing and misleading.
3. As has already been mentioned, not all of the material given to Mr Dohrmann was put before the Tribunal. The Tribunal was not given the two emails which apparently contributed to Mr Dohrmann's change of opinion. What facts were asserted in those emails was not established by the evidence. The employer contends that it may be inferred that the contents were reflected in the witness statements from Mr Fussell and Mr Flannigan which were given to the Tribunal. Assuming that to be true, the worker contends that the following matters are significant:
   • there were no witnesses to any incident on 20 February 2020;
   • the worker left work on 21 February 2020 without mentioning an injury and for a family related reason;
   • he did not drive across Tasmania on 21 February 2020;
   • while at work between 5 and 10 March 2020 the worker, in his conversations with Mr Flannigan, disclaimed any inability to do his normal duties and Mr Flannigan noticed no sign of symptoms.
4. Those matters are to be judged along with the evidence from Mr Flannigan's statement that during the same period, that is between 5 and 9 March, the worker told him he had a "bit of a sore shoulder", although he thought it would "come good", and that it was when he "moved a bullet weight and that's when he felt something". The statements made by the worker were at least enough to prompt Mr Flannigan to ask the worker if he needed to perform modified duties, although he gave no indication that he was "anything other than fine to continue as normal as he did". After 10 March the worker did not work again until he notified Mr Fussell of an injury on 16 March 2020 in advance of the proposed commencement of his next roster on 19 March 2020.
5. In my opinion the Chief Commissioner was also entitled to take into account the particularity and consistency of the worker's complaints to Dr Saul and to Mr Dohrmann about the event on 20 February 2020 when viewed in light of his description of the incident on the claim form. Although not reported by those medical practitioners in identical terms, they are all to much the same effect, and are consistent with the description given by the worker in the claim form. He told Dr Saul that he felt "sudden pain in neck and when with lifting right arm" after lifting a heavy weight. Mr Dohrmann said he was told that the task the worker was performing involved "lifting a weight slightly in order to untie something the weight being in the middle of a fishing net". The employer contends, relying on Military Rehabilitation and Compensation Commission v May, that a "cold feeling" is not an injury, but that does not accurately represent the nature of the worker's complaint. In May, the High Court was considering what may constitute an injury in the primary sense. In the context of a claim based on aggravation of a pre-existing disease, a worsening of symptoms is sufficient, provided it has the necessary causal connection to employment. In any event, I do not think it can fairly be said that Mr Dohrmann's report confines the worker's description of his symptoms to a "cold feeling". Mr Dohrmann reported the worker having said that he thought "the symptoms might settle of their own accord" but subsequently developed weakness in his right arm. The worker complained of pain to Dr Saul.
6. The Commissioner was also entitled to have regard to the absence of evidence or suggestion of some other event which may have precipitated the emergence of the symptoms experienced by the worker. The possibility that the natural progression of the worker's disease coincidentally resulted in the symptoms, may be accepted, but, on the other hand, there was no dispute that there was a strong temporal link to the event described by the worker to have occurred on 20 February 2020, following a long period of an apparently asymptomatic condition, and no suggestion to the worker that his account might have been false.
7. As Evans J pointed out in St Helens Oysters Pty Ltd v Coatsworth at [14], "in the context of litigation, a final determination as to the existence of such a condition and the causative role of any factor, almost invariably turns upon the adjudicator's assessment of the veracity and reliability of the complainant". However, in the circumstances of this case, and having regard to the material which was before the Tribunal, I think the Chief Commissioner was entitled to conclude that the only plausible explanation for the emergence or worsening of the worker's condition which led to his incapacity was that his employment was the major or most significant contributing factor to that aggravation. It is, in my view, the type of case in which reasonable minds could differ as to the existence of an arguable case. So viewed, the Commissioner's determination and order cannot amount to an error in point of law. This ground fails.

1. The second ground of appeal asserts that the learned Chief Commissioner "erred in law in by failing to evaluate the appellant's case by reference to whether, on the evidentiary materials relied on by the appellant, there existed a reasonable chance that the respondent would be unable to discharge the onus of proof that would rest upon him at a final hearing by virtue of s 49(2)(a) of the Act."
2. The contention cannot succeed. At [67] of her reasons the Commissioner correctly stated the test to be applied in these terms:

"[67] With respect to a s81A referral, a reasonably arguable case will only exist if it is reasonably arguable on the material or identified deficiencies or weaknesses in the claim that, following a contested hearing the claim may be rejected. In this case the test in St Helens Oysters Pty Ltd v Coatsworth (supra) has not been satisfied and the employer has not shown that a reasonably arguable case exists."

1. To the extent that this ground asserts that the Chief Commissioner failed to evaluate the referral by reference to the principle she stated, it could only be a complaint about the result, and adds nothing to the first ground.

1. By this ground the appellant asserts that the Chief Commissioner "erred in law in concluding that Mr Peter Dohrmann's opinion was so equivocal and/or irrelevant that it was impossible to be satisfied that any evidence he might give, and which the appellant might adduce at a contested hearing, could contradict the respondent's claims as to how and when the respondent's diagnosed condition manifested itself".
2. The Tribunal's duty was to determine the reference on the material before it. The onus was on the employer to establish that is had a reasonably arguable case, and to deliver the evidentiary material upon which it relied, or identify weaknesses or deficiencies in the worker's claim. The Tribunal was not required to consider what evidence Mr Dohrmann, or the worker, may give at a future contested hearing. To establish a reasonably arguable case it is not sufficient for the employer to indicate that it simply wished to put the worker to proof: Vos Construction & Joinery Pty Ltd v Norton-Smith (above) at [5]. In St Helens Oysters Pty Ltd v Coatsworth Evans J explained that an interim determination made under s 81A does not bind the Tribunal in future proceedings to the same result, for example on the hearing of a reference under s 42, which may be determined following a fully contested hearing and on the basis of very different evidentiary material.
3. Properly viewed, this ground requires consideration of whether the uncertainty expressed by Mr Dohrmann in his second report about the causal relationship between the aggravation or acceleration of the worker's underlying spinal disease and his employment necessitated the conclusion that the employer had a reasonably arguable case. For reasons I have already given, it did not. This ground fails.

1. For the foregoing reasons, none of the grounds of appeal are made out. The appeal is dismissed.