Comcare v Lilley

INTRODUCTION AND SUMMARY 1 This appeal under s 44(1) of the Administrative Appeals Tribunal Act 1975 (Cth) has raised questions of the validity of certain parts of Comcare's Guide to the Assessment of the Degree of Permanent Impairment (2nd ed), and the construction of the Guide adopted by the Administrative Appeals Tribunal (the Tribunal) in considering the respondent's claim for compensation. 2 As to the appeal, we agree with the learned trial judge that the Tribunal misconstrued and misapplied Table 9.7 of the Guide in determining whether Mr Lilley met the threshold for compensation for permanent impairment. We do not agree with the learned trial judge that the criteria for 5% and 10% whole person impairment in Table 9.7 of the Guide are invalid. Nor do we agree with the respondent's alternative argument about invalidity. Accordingly, the declaration made by the learned trial judge will be set aside, but otherwise his Honour's orders setting aside the Tribunal's decision and remitting the matter to the Tribunal will remain. 3 The respondent filed a Notice of Contention and at the hearing sought to add further grounds. We grant leave to add one ground, but otherwise refuse leave. On the grounds raised in the amended Notice of Contention, we agree with the parties' construction of the word "unable" in Table 9.7 as meaning something less than "impossible", however we do not agree with the respondent that the Tribunal adopted an incorrect construction of the word in the way it applied Table 9.7 to Mr Lilley's injuries. Were it necessary to decide, we do not agree with the respondent that the Tribunal failed to deal with evidence that Mr Lilley met an alternative minor criterion about the use of a ramp at the 10% whole person impairment threshold. Nor do we consider the way the Tribunal dealt with aspects of Mr Lilley's claim in its reasons involved any denial of procedural fairness to Mr Lilley. 4 Since the matter will be remitted to the Tribunal, success on any of the alternative grounds in the amended Notice of Contention would not have altered the orders in the appeal in any event. 5 What follows are our reasons for these conclusions.

BACKGROUND AND PROCEEDINGS 6 The respondent, Mr Lilley, commenced work as a firefighter in 1988. His fire brigade training involved strenuous exercise including running 7 km a day and hauling heavy equipment up training towers. He reported developing pain in his legs after performing strenuous exercise and by 2005 the pain had worsened. On 1 July 2005, his then GP diagnosed him as suffering from bilateral compartment syndrome, probably caused by his work in the fire brigade, which led him to make a claim for compensation under the Safety, Rehabilitation and Compensation Act 1988 (Cth) (the SRC Act) on 4 July 2005. From that time Mr Lilley has undergone several bouts of surgery, and has participated in rehabilitation and modified work programs, including retraining. However, by mid-2007 he was diagnosed with psychiatric problems and has not worked since August 2009. He is also a type 1 diabetic and was fitted with an insulin pump in 2007. The Tribunal found, and it is not disputed, that Mr Lilley has cooperated to the best of his ability in his rehabilitation and work placement programs, and in the compensation process. 7 On 12 January 2009, Mr Lilley lodged a claim for compensation pursuant to s 24 of the SRC Act on the basis that his injury had resulted in permanent impairment. That claim was rejected on 20 May 2009, and the rejection was upheld on review by a decision made on 26 February 2010. Mr Lilley then sought review in the Tribunal by an application filed on 19 March 2010. 8 There were only two matters in issue before the Tribunal: first, the degree of permanent impairment suffered by Mr Lilley as a result of the injuries Comcare accepted he has; and second, whether Comcare was liable to pay compensation by way of non-economic loss pursuant to s 27 of the SRC Act. This latter issue does not arise on the appeal. 9 There was evidence before the Tribunal, which it appeared to accept, of two injuries. The compartment syndrome (which the Tribunal described in [1] of its reasons as "pain affecting the front and sides of both legs when running or walking") was the principal work-related injury. The second injury - damage to the peroneal nerve - was accepted by the parties and the Tribunal to have arisen as a consequence of surgery Mr Lilley underwent to remove a neuroma of the superficial peroneal in his left leg, which was related to his compartment syndrome. 10 The main issue before the Tribunal concerned whether Mr Lilley reached the 10% impairment threshold for his compartment syndrome injury. It was clear in the materials before the Tribunal that the damage to his peroneal nerve did not of itself result in impairment capable of meeting the 10% threshold in the SRC Act, to which we refer in more detail below; rather, the whole person impairment in respect of this injury was at a level of 2%. 11 The Tribunal found that Mr Lilley's compartment syndrome injury also did not meet the minimum 10% threshold for compensation set out in s 24(7) of the SRC Act. It is this finding which was critical to the outcome of the appeal before the learned trial judge and before this Court. 12 The Tribunal also rejected a challenge to the validity of Tables 9.6.2a and 9.7 in the Guide, brought on the grounds the criteria used were unreasonable and disproportionate. 13 On appeal under s 44(1) of the AAT Act, the learned trial judge held that the Tribunal wrongly took the view that the activities set out in the criteria contained in Table 9.7 required clinical testing and so asked itself the wrong question in determining Mr Lilley's claim to compensation. His Honour also found parts of Table 9.7 to be invalid, not on the grounds advanced on behalf of Mr Lilley, but rather because some of the criteria failed to fix an objective standard by which an assessment could be conducted and in so failing created uncertainty, which was, in his Honour's opinion, fatal to the validity of those particular criteria. 14 Comcare appealed to this Court. Only two grounds in the Notice of Appeal were pressed. They were: 1. His Honour Rares J erred in finding that the Administrative Appeals Tribunal made an error of law in finding that under Table 9.7 of the Comcare Guide to the Assessment of the Degree of Permanent Impairment (2nd ed) (the Guide) "each of the activities of ability to walk and climb stairs and the pace of walking required clinical testing" and that, in so doing, it constructively failed to exercise its jurisdiction. The Tribunal made no such finding. 2. His Honour erred in declaring that "the criteria for 5% and 10% whole person impairment in Table 9.7 in Part 1 Division 1 of [the Guide] are invalid and of no effect." In particular, His Honour erred in finding that: 2.1 the 5% criterion that a person is able to walk up 3 stairs unaided is not reflective of any measure of impairment; 2.2 the expressions "three or more stairs" and "a ramp" have no content; 2.3 the dimensions of the ramp are like the "or more stairs" entirely unspecified; 2.4 the words "is unable to" in the 10% criterion suggest complete inability and disentitle a person who may complete the task very slowly and with great difficulty; and 2.5 in light of these matters, the decision maker is given an unfettered power to determine the criteria. 15 Mr Lilley filed a Notice of Contention raising two points: one about the construction of the word "unable" in Table 9.7, and a re-agitation of the unreasonableness/disproportionality argument about the validity of the criteria in the Guide. 16 On the hearing of the appeal, Mr Lilley's senior counsel sought leave to add four further grounds to the Notice of Contention. A proposed amended Notice of Contention was filed the day following the hearing, on 7 August 2013. The new grounds were: 3A. The primary judge erred in failing to remit the matter for reconsideration on the basis that the Tribunal misconstrued the meaning of the word "unable" in Table 9.7 at 10%. Ramp 10. The primary judge erred in failing to remit the matter for reconsideration on the basis that the Tribunal failed to consider whether Mr Lilley satisfied the second minor criterion at 10% in that he was relevantly "unable to negotiate … a ramp (up and down) without the use of a walking aid or hand rails". Procedural Fairness 11. The primary judge erred in failing to remit the matter on the basis that the Tribunal denied Mr Lilley procedural fairness in failing to disclose to him, during the hearing or before judgment, that the Tribunal considered, notwithstanding the express terms of Table 9.7, that the activities identified in paragraph 36 of its reasons should have been tested clinically and that it proposed to approach its determination of the correct or preferable decision under the Guide on the basis that: 11.1 The Tribunal would only ascribe weight to medical evidence based on clinical testing; 11.2 Mr Lilley's account of his circumstances would not be accepted or taken into account unless corroborated. Relief 12. If the declaratory relief ordered by the primary judge was too broad, he ought to have declared invalid the whole of the second minor criterion at 10% of Table 9.7 of the Guide. 17 Grounds 3A and 11 were raised to some extent in the Notice of Appeal before the learned primary judge, but those matters were not decided. Ground 10 was not raised in the Notice before the trial judge. 18 Neither the Court nor Comcare had notice of the application to amend the Notice of Contention in the form and to the extent foreshadowed by Mr Lilley's counsel at the hearing. The Court granted leave to Comcare to file and serve submissions on whether the Court should grant leave to amend and on the substance of the new grounds. Those submissions were filed in accordance with the Court's orders on 21 August 2013. 19 Comcare ultimately did not oppose the grant of leave. That does not take away from the undesirability of the approach taken on behalf of Mr Lilley. The Court's resources, and those of other parties, are to be carefully harnessed in an appeal by preparation directed to those matters each of the parties informs the Court is in issue between them. The detailed processes in this Court for the preparation of appeals should not be lightly sidestepped by the late raising of new issues in an appeal. This is especially so where no notice has been given of the proposed amendment in written submissions, and no proposed amended notices have been filed. We indicate our disapproval of the approach taken on behalf of Mr Lilley in this case, and the difficult position in which it placed Comcare, and the Court. 20 The grant of leave to amend in an appeal is generally determined by what is in the interests of the administration of justice, in particular taking into account any prejudice to other parties and the appropriateness of all matters in issue between the parties being determined: see Teoh v Minister for Immigration and Ethnic Affairs (1994) 49 FCR 409 at 416 per Lee J. 21 Increasingly, however, this Court recognises that granting leave to raise new points on appeal can involve injustice even without prejudice to the other party. The injustice stems from the disturbance created to the proper functioning of an appellate review process. In H v Minister for Immigration and Multicultural Affairs (2000) 63 ALD 43 at [8], and after recalling that the appellate jurisdiction of this Court exists for the correction of error, the Full Court observed: In our view, the readiness with which appeal courts have in the past been satisfied that it is expedient in the interests of justice to allow a fresh point to be argued and determined on appeal is unlikely to continue into the future. The volume and complexity of the cases presently required to be heard and determined by the intermediate appellate courts of Australia is such that it is increasingly important that such courts are able to devote their time to the genuine review of first instance decisions. It is becoming increasingly difficult, in our view, to establish that it is expedient in the interests of justice that the time of three or more judges should be spent giving original consideration to issues that ought to have been raised before the primary judge. The interests of justice in this sense extend beyond the interests of the parties to the appeal to encompass the interests of other litigants whose appeals require hearing and determination, and the broad public interest in efficient judicial administration. 22 In H, after hearing full argument on the proposed amendments, the Court considered there was little merit in the issues sought to be raised by the appellant, as they were not issues of general importance to the proper administration of the relevant Act but arose out of the particular circumstances of the appellant. The Court noted there was no evidence explaining why the ground was not raised before the primary judge. The Court refused leave to the appellant to rely on the new ground. 23 We consider the approach in H has some parallels in the current appeal. Ground 3A was raised in similar terms before the learned trial judge, ground 11 was only raised in part and ground 10 was not raised at all. None of them were decided by the primary judge, and therefore the raising of those matters before a Full Court was not for the correction of error. The omission from the Notice of Contention (in the form it took until the day of the appeal) of matters raised before the trial judge is unexplained. Nevertheless, ground 3A raises issues concerning the interpretation of the Guide which are capable of having application outside Mr Lilley's case. For that reason we grant leave in respect of that ground. We consider grounds 10 and 11 are without merit, for the reasons we set out at [105] to [111] below, and we refuse leave to amend to include them. Given our conclusion on validity, ground 12 does not arise and we refuse leave for that reason.

LEGISLATIVE FRAMEWORK 24 Subject to some exceptions not presently material, by s 14(1) of the SRC Act, Comcare is liable to pay compensation in accordance with the SRC Act in respect of an injury suffered by an employee if the injury results in death, incapacity for work, or impairment. 25 "Impairment" is defined in s 4 of the SRC Act to mean "the loss, the loss of the use, or the damage or malfunction, of any part of the body or of any bodily system or function or part of such system or function". The adjective "permanent" is defined in s 4 to mean "likely to continue indefinitely". 26 Where an injury results in a permanent impairment, s 24(1) of the SRC Act imposes a liability on Comcare to pay lump sum compensation. The amount of compensation is to be calculated by reference to a percentage of the "maximum amount" prescribed in s 24(9), as indexed: see ss 24(3) and (4). The degree of permanent impairment is to be expressed as a percentage (s 24(6)) and the percentage reflecting the degree of permanent impairment is to be determined "under the provisions of the approved Guide" (s 24(5)). 27 If an employee has a permanent impairment other than hearing loss, Comcare's liability to pay compensation does not arise if Comcare determines the degree of permanent impairment is less than 10%: s 24(7). 28 The "approved Guide" referred to in s 24(5) is a document prepared pursuant to s 28 of the SRC Act. Section 28 provides: (1) Comcare may, from time to time, prepare a written document, to be called the "Guide to the Assessment of the Degree of Permanent Impairment", setting out: (a) criteria by reference to which the degree of the permanent impairment of an employee resulting from an injury shall be determined; (b) criteria by reference to which the degree of non-economic loss suffered by an employee as a result of an injury or impairment shall be determined; and (c) methods by which the degree of permanent impairment and the degree of non-economic loss, as determined under those criteria, shall be expressed as a percentage. (2) Comcare may, from time to time, by instrument in writing, vary or revoke the approved Guide. (3) A Guide prepared under subsection (1), and a variation or revocation under subsection (2) of such a Guide, must be approved by the Minister. (3A) A Guide prepared under subsection (1), and a variation or revocation under subsection (2) of such a Guide, is a legislative instrument made by the Minister on the day on which the Guide, or variation or revocation, is approved by the Minister. (4) Where Comcare, a licensee or the Administrative Appeals Tribunal is required to assess or re-assess, or review the assessment or re-assessment of, the degree of permanent impairment of an employee resulting from an injury, or the degree of non-economic loss suffered by an employee, the provisions of the approved Guide are binding on Comcare, the licensee or the Administrative Appeals Tribunal, as the case may be, in the carrying out of that assessment, re-assessment or review, and the assessment, re-assessment or review shall be made under the relevant provisions of the approved Guide. (5) The percentage of permanent impairment or non-economic loss suffered by an employee as a result of an injury ascertained under the methods referred to in paragraph (1)(c) may be 0%. (6) In preparing criteria for the purposes of paragraphs (1)(a) and (b), or in varying those criteria, Comcare shall have regard to medical opinion concerning the nature and effect (including possible effect) of the injury and the extent (if any) to which impairment resulting from the injury, or non-economic loss resulting from the injury or impairment, may reasonably be capable of being reduced or removed. (8) Comcare shall make copies of the "Guide to the Assessment of the Degree of Permanent Impairment" that has been approved by the Minister, and of any variation of that Guide that has been so approved, available upon application by a person and payment of the prescribed fee (if any). 29 The term "approved Guide" is defined in s 4 of the SRC Act to mean: (a) the document, prepared by Comcare in accordance with section 28 under the title "Guide to the Assessment of the Degree of Permanent Impairment", that has been approved by the Minister and is for the time being in force; and (b) if an instrument varying the document has been approved by the Minister - that document as so varied. 30 The version of the approved Guide that is applicable in these proceedings is the Guide to the Assessment of the Degree of Permanent Impairment, 2nd ed, 2005. Pursuant to s 28(3A) it is a legislative instrument. 31 The Guide is divided into two principal parts, dealing with defence related and non-defence related claims. The latter are dealt with in Pt 1. Part 1 of the Guide has three divisions: Div 1 is used to assess the degree of an employee's permanent impairment; Div 2 is used to assess the degree of an employee's non-economic loss and Div 3 is used to calculate the total entitlement of an employee based on the assessments in Divs 1 and 2. After a section entitled "Principles of Assessment" to which we refer below, Div 1 of Pt 1 is then divided into chapters, each dealing with different parts of the body's system. The relevant chapter in respect of Mr Lilley's injuries is Ch 9 - "The Musculoskeletal System". 32 A number of matters which bear on the construction and operation of the Guide are set out in the section in Div 1 entitled "Principles of Assessment". These matters flow from the fundamental change of focus brought about by the 1988 legislation, from the "table of maims" in the 1971 legislation to a "whole person impairment" approach. The "whole person impairment" approach was derived from the approach taken in the Veterans' Entitlements Act 1986 (Cth) and also from the Guides to the Evaluation of Permanent Impairment, American Medical Association, Chicago, 1984 (the AMA Guides). Reliance on the AMA Guides is expressly acknowledged in s 5 of the Principles of Assessment, at p 12 of the Guide. Section 5 then states: Division 1 assembles into groups, according to body system, detailed descriptions of impairments. The extent of each impairment is expressed as a percentage value of the whole, normal, healthy person. Senior counsel for Comcare accepted that the word "extent" in this paragraph meant "degree". 33 In describing the concept of "degree of impairment", and after having referred to the definition of 'impairment' in s 4 of the SRC Act, the Guide states (at p 11, in s 1 of Pt 1): It relates to the health status of an individual and includes anatomical loss, anatomical abnormality, physiological abnormality, and psychological abnormality. The degree of impairment is assessed by reference to the impact of that loss on the normal efficient functioning of the whole person. 34 Section 28(1) of the SRC Act requires the Guide to set out both "criteria" by which the degree of permanent impairment is to be ascertained, and "methods" to express that degree as a percentage (so as to give effect to the requirement in s 24(6)). The approach adopted by the Guide differs depending on the part of the body system under consideration. The determination of the degree of impairment is generally prescribed to be undertaken by reference to tables in respect of particular kinds of impairments arising from injuries. Sometimes there is one set of criteria; sometimes there are "primary" and "secondary" criteria; sometimes there are "major" and "minor" criteria. Sometimes there are matters which are not expressly labelled as criteria at all, but are called "description of effect" or "description of level of impairment". The "method" aspect of the Guide is less obvious, in the sense that only in a few places are there actually calculations prescribed to be undertaken to arrive at a percentage for the degree of impairment. Mostly, the tables simply state a percentage for the degree of impairment. 35 The criteria as found in the various tables in the Guide are to be understood in the context of the Guide's overall approach, expressed in the Principles of Assessment, taking into account the definition of "whole person impairment" (at p 16 of the Guide): Whole person impairment (or WPI) means the medical effects of an injury or disease. WPI is based on the American Medical Association's Guides to the Evaluation of Permanent Impairment. WPI is a medical quantification of the nature and extent of the effect of an injury or disease on a person's functional capacity including Activities of Daily Living. This Guide presents descriptions of impairments in chapters and tables according to body system. The extent of each impairment is expressed as a percentage value of the functional capacity of a normal healthy person. 36 Each chapter of the Guide deals with a discrete aspect of the body's system of functioning. In each chapter there are set out the applicable "Activities of Daily Living" by which the effect of the injury or disease on a person's functional capacity is to be assessed. 37 When turning to the particular chapter and table in issue in Mr Lilley's case, it is important to bear in mind these general features of the Guide, and the operation of the Principles of Assessment. They demonstrate the flexibility which is needed across the range of injuries covered by the Guide, for the assessment process to operate effectively in relation to different kinds and levels of injuries. They also reveal the Guide's emphasis on assessing how an injury affects an employee's capacity to function in her or his daily life, at a very practical level. We are not the first to point out that there are many inconsistencies of expression in the Guide and ambiguities in how it might operate at the specific level of individual impairment. So much was forcefully said by the Full Court in Whittaker v Comcare (1998) 86 FCR 532 at 538-539. In that case (to which we refer in more detail below) the ambiguities were so great the Court felt unable to fill the gap through a process of interpretation. That is not the situation here. We consider these introductory parts of Pt 1 support a pragmatic and practical approach to the construction of terms used in particular tables within Pt 1, where those terms are designed to describe activities of daily living that an employee can ordinarily be expected to encounter. 38 Table 9.7 in Ch 9 of the Guide is critical to the resolution of this appeal. It is to be noted that Table 9.7 expressly states that two minor criteria and one major criterion must be satisfied for the relevant threshold to be met. 39 Table 9.7 provides: Table 9.7: Lower Extremity Function % WPI Major Criteria Minor Criteria (at least one required) (at least two required where listed) Walks at a normal pace in comparison with peers on level ground or uneven ground and can avoid obstacles; 0 or Distance walked is not restricted by the condition being assessed (although other factors such as the level of fitness may cause restriction). Walks at a normal pace in comparison with peers on level ground but has manifest difficulty negotiating uneven ground and avoiding obstacles; Legs give way or lock occasionally without resulting in falls. 5 or Can negotiate three or more stairs or a ramp (up and down) without the use of a walking aid or hand rails. Walking is restricted to 1000m or less at a time (may be able to walk further after resting). Walks at a normal pace in comparison with peers on level ground but is unable to negotiate uneven ground without use of a walking aid or personal assistant; Legs give way or lock occasionally without resulting in falls. 10 or Is unable to negotiate three or more stairs or a ramp (up and down) without the use of a walking aid or hand rails. Walking is restricted to 500m or less at a time (may be able to walk further after resting). Walks at a moderately reduced pace in comparison with peers on level ground; Legs give way occasionally resulting in falls. 20 or Is unable to negotiate three or more stairs or a ramp (up and down) without use of rails. Walking is restricted to 250m or less at a time (may be able to walk further after resting). Is unable to rise from sitting to standing position without use of one hand but can stand without support. Walks at a significantly reduced pace in comparison with peers on level ground; Legs give way frequently resulting in falls. 30 or Demonstrated medical need for a brace or walking aid (walking stick or crutches) on level ground. Walking is restricted to 100m or less at a time (may be able to walk further after resting). Is unable to negotiate three or more stairs or a ramp (up and down) without assistance from someone else. Is unable to rise from sitting to standing position without use of both hands but can stand without support. Walks at a greatly reduced pace in comparison with peers on level ground; Is restricted to walking around house and yard. 40 or Demonstrated medical need for a walking aid (walking stick or crutches) when walking on level ground. Walking is restricted to 50m or less at a time (may be able to walk further after resting). Is unable to negotiate three or more stairs or a ramp (up and down) under any circumstances. Is unable to rise from sitting to standing position without personal assistance and is unable to stand without support. Walks at a very slow pace in comparison with peers on level ground; Is restricted to walking around house. 50 or Demonstrated medical need for a quad stick or walking frame as support when standing and walking. Walking is restricted to 25m or less at a time (may be able to walk further after resting). Is unable to negotiate any steps or ramps. Is unable to rise from sitting to standing position without personal assistance and is unable to stand without support. 60 Can stand with support of personal assistant but is unable to walk. 64 Unable to stand or walk.

40 The Activities of Daily Living which are to be used in assessing functional capacity under Table 9.7 are those contained in Pt 9 at p 74 of the Guide: Figure 9-A: Activities of Daily Living Activity Examples Self care, personal hygiene. Bathing, grooming, dressing, eating, eliminating. Communication. Hearing, speaking, reading, writing, using keyboard. Physical activity. Standing, sitting, reclining, walking, stooping, squatting, kneeling, reaching, bending, twisting, leaning, carrying, lifting, pulling, pushing, climbing, exercising. Sensory function. Tactile feeling. Hand functions. Grasping, holding, pinching, percussive movements, sensory discrimination. Travel. Driving or travelling as a passenger. Sexual function. Participating in desired sexual activity. Sleep. Having a restful sleep pattern. Social and recreational. Participating in individual or group activities, sports activities, hobbies.

41 Page 84 of the Guide bears the heading "Lower Extremity Function" and contains notes intended to be read with Table 9.7 on the following page. The legal role and effect of this page of notes is unclear. In neither form nor substance are they marginal or textual notes of the kind usually found in principal or delegated legislation: cf Parker v Minister for Sustainability, Environment, Water, Population and Communities [2011] FCA 1325. Rather, the text and content of these notes suggest they have always been intended to be operative parts of the Guide. They are instructions and prohibitions apparently directed at some points to medical assessors and at other points to those making a determination pursuant to s 24 of the SRC Act. Pursuant to s 28(4), as part of the Guide they are binding on Comcare delegates and the Tribunal. However, like all parts of the Guide, to have such an effect they must be authorised by the terms of s 28(1) of the SRC Act. Whether these notes are authorised by s 28(1), including whether there is any statutory authorisation for instructions in the Guide to medical assessors, is not an issue raised on this appeal. However, the meaning of one part of the notes is relevant to the determination of one of the issues in the appeal. 42 At the end of the notes on p 84, the following statements appear: To fulfil the requirements of a WPI rating in Table 9.7, there must be one major criterion, and at least two minor criteria, present (where minor criteria are listed). "Manifest difficulty" is difficulty (such as stumbling, or an altered gait) evident to the medical assessor. The difficulty must be tested clinically: history alone cannot be relied upon in the assessment. 43 Read literally, the second paragraph (read with the mandatory requirement to satisfy one major and two minor criteria) imposes a requirement on Comcare to determine a person has "manifest difficulty" for the purposes of the major criterion at the 5% WPI level in Table 9.7 only if the employee has undergone clinical testing in the sense of some kind of observational evaluation of how she or he could or could not manage each of the activities specified in the applicable criteria. If that were its meaning we would be inclined to the view that such an instruction was either not authorised by the terms of s 28 of the SRC Act, or so unreasonable or irrational (for example because the requirement applies only to satisfaction of this single criterion) as to be invalid. 44 However, we do not read the two paragraphs in that way. Rather, because of the reference to a "medical assessor", rather than to Comcare, we read that sentence as directed at any person conducting a medical assessment which is to be submitted to Comcare for the purpose of its determination. The direction to the medical assessor is to the effect that the medical assessor must examine the person concerned and in that sense the "manifest difficulty" must be evident to the assessor, as opposed to the assessor simply relying on what the person tells the assessor. The paragraph can be seen as an instruction about how the word "manifest" is to be understood in this context. 45 This construction also accords with the context in which these notes are found. There is no apparent reason why the assessment of the "manifest difficulty" criterion should be treated any differently to the assessment of the other criteria: all involve the extent to which a person can use her or his legs in normal daily activities. As we have noted above, the validity of this instruction in the Guide (or others like it) was not raised in the appeal and accordingly we do not decide it.

ISSUES ON THE APPEAL 46 The term "injury" is used in the SRC Act to describe the resultant effect of an incident or ailment upon an employee's body, and is not used in a global sense to describe the general condition of an employee following an incident or ailment: see Canute v Comcare (2006) 226 CLR 535 at [10]. The statutory task under s 24 thus revolves around the occurrence of an "injury", so that more than one injury can result from a single workplace incident, and each injury must be separately assessed. Although the determination of the degree of impairment arising from an injury is to be carried out by measuring the effect against the "whole person", the High Court's decision in Canute emphasises the whole person impairment approach operates in respect of a specific injury. 47 Comcare submitted, by reference to what had been said by the Full Court in Whittaker 86 FCR 532 at 543-544, the need to construe the Guide in a common sense manner, by reference to what an ordinary person could expect to confront as he or she goes about ordinary day-to-day activities, remembering that the overall objective is to determine the extent to which the employee is impaired when compared to a normal healthy person. We accept that submission. Given the weaknesses of drafting and expression present in the Guide, the construction task may not be straightforward. Nevertheless, the Court must strive to give the various parts of the Guide a workable construction and that is more easily achieved using this touchstone. 48 This approach to construction of the Guide informs both the issues on Comcare's appeal, and some of those raised in the respondent's Notice of Contention.

Comcare's grounds of appeal 49 Comcare contended the learned trial judge was wrong to make the two findings we have summarised at [13] above: first, the finding that the Tribunal erred in requiring evidence of clinical testing before it would accept that the criteria in Table 9.7 had been met and, second, that the criteria for 5% and 10% whole person impairment in Table 9.7 are invalid by reason of uncertainty and failure to fix an objective standard. 50 On the clinical testing issue Comcare contended that, fairly and properly construed, the impugned passages of the Tribunal's reasons demonstrated nothing more than a weighing of the evidence before the Tribunal, as its function required. The Tribunal's language was, Comcare submitted, the legitimate language of a merits decision-maker in preferring some evidence over other evidence. 51 On the invalidity issue, Comcare contended that the Guide should be construed in the common sense way to which we have referred at [47] above, remembering the overall objective of the SRC Act and the Guide is to determine the extent to which an employee is impaired when compared to a normal healthy person. Comcare contended the learned trial judge had not adopted such an approach and was wrong to have found the criteria as expressed to be illogical, uncertain or nonsensical. Much of this debate centred on two expressions in the Table 9.7 criteria: "three or more stairs" and "a ramp". 52 We agree with Comcare that the learned trial judge was wrong to find the criteria in Table 9.7 invalid. We do not agree he was wrong to find the Tribunal misconstrued the operation of Table 9.7 and approached its task as if the criteria could not be satisfied without clinical testing supporting their satisfaction.

Our reasoning: the clinical testing issue 53 At [36] and [37] of its reasons the Tribunal stated: The notes to Table 9.7 require that "manifest difficulty", an element of one of the major criteria at the 5 per cent level, be tested clinically. At the same time, ability to walk and pace of walking, ability to climb stairs or a ramp, and to rise from a seated position, are activities included in the criteria for several levels of impairment in the Table. Each of these activities invites clinical testing. So although the notes do not similarly indicate that they must be tested clinically - presumably because in more severe cases a person may either be incapable of managing the exercise or at least of doing so without considerable discomfort - the Tribunal considers that outside these circumstances, the activities should have been tested clinically. The Tribunal notes that with the exception of Associate Professor Oakeshott, the assessments of the medical practitioners were based on Mr Lilley's history, rather than independent clinical assessment. That has detracted from the weight to be attributed to their testimony. 54 Paragraphs [36] and [37] of the Tribunal's reasons reveal: (a) The Tribunal started at [36] with the two sentences from the notes on p 84 of the Guide and appears to have taken them literally. (b) The Tribunal then considers why it is that other criteria do not appear subject to the same restriction. Rather than explaining that difference by reading down the instruction about "manifest difficulty" (which is what in our opinion was required), the Tribunal adopts and applies the approach in that instruction to the other activities in the criteria. (c) That is why the Tribunal concludes this paragraph with the phrase "should have been tested clinically". The word "should" here is used, we consider, to convey a sense of requirement. We reject Comcare's interpretation that the Tribunal is doing no more than expressing a preference. (d) At [37], the Tribunal reinforces the view it has formed about the essentiality of clinical testing for all the activities in the criteria in Table 9.7. That is evident because of the way it discounts the opinions of Dr Bodel and Dr Le Leu, which we discuss below. In isolation, we accept it is likely one might read a sentence which states "[t]hat has detracted from the weight to be attributed to their testimony" as nothing more than a trier of fact giving preference to some evidence over other evidence. However, this sentence in the Tribunal's reasons is not to be read in isolation. When read with what follows about the evidence of Dr Bodel and Dr Le Leu, we consider it is part of an erroneous reasoning process. (e) Finally, it is unclear what extra work the Tribunal intended the word "independent" to do in its phrase "independent clinical assessment". If anything, it suggests the Tribunal was placing a further gloss on the construction of the criteria by requiring not only clinical testing, but clinical testing by persons other than those who might be involved with the employee's treatment or rehabilitation. 55 We consider this a fair reading, without undue technicality. These paragraphs are the centrepiece of the Tribunal's approach to the main issue before it: they set the benchmark against which the Tribunal then assesses the evidence before it. We do not accept Comcare's submission that these paragraphs contain the language of a weighing exercise only. 56 Our reading is confirmed by other parts of the Tribunal's reasons. 57 The Tribunal spent a disproportionate amount of time in its reasons discussing and evaluating the evidence of Associate Professor Oakeshott. In our view, this is explained by the Tribunal's approach to its task as one which needed evaluation by clinical testing and Associate Professor Oakeshott was the only clinician who attempted to test Mr Lilley by asking him to perform the activities set out in the criteria. That explains the Tribunal's rather more cursory treatment of the reports of Dr Bodel and Dr Le Leu. 58 Having recognised the flaw in Associate Professor Oakeshott's report about the testing of Mr Lilley's ability to walk 500 m (because Associate Professor Oakeshott tested Mr Lilley only over 356 m), the Tribunal at [50] then simply discounts that aspect of the evidence. It did not otherwise return to this second major criterion (although Dr Bodel and Dr Le Leu had both found this criterion was met in respect of Mr Lilley). That is best explained by the Tribunal considering it needed to seek out evidence based on clinical testing. 59 Next, at [55], the Tribunal found Associate Professor Oakeshott's testing of Mr Lilley in respect of the other major criterion - ability to negotiate uneven ground without a walking aid or personal assistant - was also affected by a flaw, because the ground traversed did not in fact meet the Tribunal's understanding of what "uneven" meant in the criteria. The Tribunal then concluded: "For that reason Mr Lilley would not be able to meet the second part of the descriptor since he was not tested over uneven ground" (emphasis added). This is despite the Tribunal earlier recognising (at [40] of its reasons) Dr Bodel had reported that Mr Lilley "cannot negotiate uneven ground without the use of a walking aid or personal assistant". The only explanation for the Tribunal's emphatic conclusion that Mr Lilley could not meet this criterion is because it saw the criterion as only capable of being satisfied through clinical testing. 60 At [56] of its reasons, the Tribunal deals with other evidence put forward by Mr Lilley. The Tribunal discounts Mr Lilley's own evidence because it is not corroborated. This is the subject of a separate ground in the Notice of Contention, to which we refer below in the context of an alleged denial of procedural fairness. We have not accepted that contention but we should not be understood in consequence to have endorsed any principle that credible evidence from laypersons is inherently entitled to only slight weight or requires corroboration. However, in the present context, what is important is the way the next sentence is expressed. The Tribunal states: In addition, the medical evidence in support of his capacity in this regard was, with the exception of the clinical findings of Associate Professor Oakeshott, based solely on Mr Lilley's reported history. (emphasis added) 61 There is nothing inappropriate, let alone unlawful, about a merits review tribunal in a case such as this preferring, in terms of weight and perhaps because of additional reliability, medical evidence based on observation and testing of an employee's capacity to perform activities set out in the Guide. However, the Tribunal's reasons at this point do not convey any sense of weighing different evidence. Rather, they convey an attitude of dismissing medical evidence because it is based on reported history and not observation by those practitioners. That does not represent a weighing exercise: it is indicative of a disregard of certain evidence because it does not have a character the Tribunal perceives is required. 62 Finally, at [58] of its reasons, the Tribunal states: Accordingly, there is no medical evidence which supports Mr Lilley meeting the minimum number of major and minor criteria in Table 9.7 for at least the 10 per cent threshold. 63 As we have observed, that statement is not correct. It is correct to say, at least on the recitation of the evidence by the Tribunal in its reasons, that there was no medical evidence from a single practitioner to that effect. However, it is the Tribunal which makes the determination under the Guide, not the medical practitioners. The Tribunal could have elected to rely on parts of the medical evidence from different practitioners to support its conclusions, although we are not suggesting it was required to do so. Rather, the fact that it made such an absolute statement to the opposite effect at the conclusion of this part of its reasons in our opinion confirms that it was not merely discounting but was dismissing medical evidence not based on clinical testing.

Our reasoning: the invalidity issue 64 The learned primary judge's opinion was that Table 9.7 did not fix an objective standard for the number of stairs or characteristics of the ramp that a claimant must be unable to negotiate without the use of an external aid, and instead left the decision-maker with an unfettered power "to determine whether more than three steps will suffice, and then how many or what particular ramp must be negotiated": Lilley v Comcare (2013) 209 FCR 275 at [40]. His Honour characterised this as an "ad hoc power" left to the decision-maker from case to case. 65 We do not agree with his Honour that there is invalidating uncertainty in the sense set out in King Gee Clothing Co Pty Ltd v Commonwealth (1945) 71 CLR 184; Cann's Pty Ltd v Commonwealth (1946) 71 CLR 210; Herald-Sun TV Pty Ltd v Australian Broadcasting Tribunal (1985) 156 CLR 1; Television Corporation Ltd v Commonwealth (1963) 109 CLR 59, or that the power is of an "ad hoc" kind in a way which renders it invalid. 66 The approach to be taken to the construction of delegated legislation, as the learned trial judge pointed out (Lilley 209 FCR 275 at [27]-[28]), is, by reason of s 13(1) of the Legislative Instruments Act 2003 (Cth) (and subject to any contrary intention), the same as that to be applied to the principal legislation. 67 In some circumstances, of which this is one, the purpose of the legislation in question may compel an approach to construction which might in other circumstances seem imprecise. That is because, viewed as a whole and in context, taking into account the purpose of the Guide, its language and terminology must be directed at medical assessments and practical activities not necessarily susceptible to high levels of precision. In Lacey v Attorney-General (Qld) (2011) 242 CLR 573, drawing on the decision of Project Blue Sky Inc v Australian Broadcasting Authority (1998) 194 CLR 355, six judges of the High Court held (at [43]-[44], citations omitted): 43 The objective of statutory construction was defined in Project Blue Sky … as giving to the words of a statutory provision the meaning which the legislature is taken to have intended them to have. … The legislative intention there referred to is not an objective collective mental state. Such a state is a fiction which serves no useful purpose. Ascertainment of legislative intention is asserted as a statement of compliance with the rules of construction, common law and statutory, which have been applied to reach the preferred results and which are known to parliamentary drafters and the courts. … 44 The application of the rules will properly involve the identification of a statutory purpose, which may appear from an express statement in the relevant statute, by inference from its terms and by appropriate reference to extrinsic materials. The purpose of a statute is not something which exists outside the statute. It resides in its text and structure, albeit it may be identified by reference to common law and statutory rules of construction. 68 The approach set out in Lacey has been applied in more recent High Court decisions, including Certain Lloyd's Underwriters Subscribing to Contract No IH00AAQS v Cross (2012) 293 ALR 412 at [24]-[25] where French CJ and Hayne J held (citations omitted): 24 The context and purpose of a provision are important to its proper construction because, as the plurality said in Project Blue Sky …, "[t]he primary object of statutory construction is to construe the relevant provision so that it is consistent with the language and purpose of all the provisions of the statute" [emphasis added]. That is, statutory construction requires deciding what is the legal meaning of the relevant provision "by reference to the language of the instrument viewed as a whole" and "the context, the general purpose and policy of a provision and its consistency and fairness are surer guides to its meaning than the logic with which it is constructed". 25 Determination of the purpose of a statute or of particular provisions in a statute may be based upon an express statement of purpose in the statute itself, inference from its text and structure and, where appropriate, reference to extrinsic materials. The purpose of a statute resides in its text and structure. 69 The Lacey approach was restated in similar terms in Akiba v Commonwealth (2013) 87 ALJR 916 at [31], where French CJ and Crennan J, citing Lacey, observed: The identification of a statute's purpose may aid in its construction. That identification may be done by reference to the apparent legal effect and operation of the statute, express statements of its objectives and extrinsic materials identifying the mischief to which it is directed. 70 Equally important in construing the Guide are the observations of the Full Court in Whittaker 86 FCR 532 at 543-544, to which we have referred above. 71 In this particular case, context and purpose are critical. The Guide is a tool, designed to be used and required to be applied, not by medical practitioners, but by Comcare delegates and the Tribunal to make decisions about a person's degree of impairment. It is concerned with how an injury has affected a person's capacity to function in daily life and as such it is directed only to the very practical matters of what a person can and cannot do, how a person does or does not present and how well (or badly) parts of a person's body function in comparison to a "whole, normal, healthy person". As the Guide states at p 11, the degree of impairment is assessed by reference to the impact of the injury "on the normal efficient functioning of the whole person". 72 Some measurements of impairment arising from injury can be very precise, because they are clinical measures - for example, diastolic blood pressure, asthma impairment, visual impairment. Others will be more qualitative, although they use well understood clinical terms - such as Ch 5, dealing with psychiatric impairment where the criteria are expressed in terms of "marked" or "definite" disturbances in thinking or behaviour. Still others, such as Ch 12, dealing with the neurological system, must also grapple with descriptions of loss of function which are less precise than a blood pressure measurement - for example, "strangers have difficulty understanding speech" or "frequent repetition and/or gestures needed". 73 In Ch 9, as with many of the other chapters, the measurement of loss of function within the musculoskeletal system in some cases involves a relatively precise measurement (such as the range of motion of a joint in flexion or extension) and in other cases involves broader descriptions. Table 9.7 is an example of a table which uses broader expressions, but there are others. In Table 9.14 there are descriptions such as "minor" or "moderate" or "major" in respect of loss of digital dexterity, and there are descriptions such as "unable to cut up food". 74 Construction of the terms and phrases used in the Guide must proceed, in our opinion, with full cognisance of this context, and in particular with a focus on how the terms are to be read with the "Activities of Daily Living" specified in each chapter. Construction must also proceed giving due weight to the purpose of the Guide as a tool to be used by assessors in providing evidence or material to support a determination under the SRC Act, and by Comcare in making such a determination. Both of these functions are designed to reach a conclusion about how a person's injury affects her or his capacity for the ordinary activities of daily life, in all its diversity and variety. 75 In this appeal, attention concentrated on the construction of two aspects of Table 9.7. First, the proper construction of the word "unable" and, second, the proper construction of the phrase "three or more stairs or a ramp". Of course, these words and phrases do not occur in isolation and indeed appear as different parts of a longer statutory expression, namely "unable to negotiate three or more stairs or a ramp (up and down) without the use of a walking aid or hand rails" in the minor criteria for establishment of 10% whole person impairment. 76 Bearing in mind the principles set out at [66]-[71] above, in our opinion the construction of these expressions must be undertaken giving weight to other textual and contextual considerations. The verb "unable" is used in many places in the Guide. There is a presumption - rebuttable by context, we accept - that a word used repeatedly in a statute should be given a consistent construction: Murphy v Farmer (1988) 165 CLR 19 at 26-28 per Deane, Dawson and Gaudron JJ. We consider there is nothing in the context of the Guide which would suggest the word "unable" should be given different meanings when it appears in different places in the Guide. To the contrary, it promotes consistency. One of the purposes of the Guide is to set out a gradation of degrees of impairment in relation to the functioning of parts of the body system and if words such as "unable" are given consistent meanings across the Guide, the way the gradation operates is also likely to be more consistent. 77 Without accepting the respondent's submissions about the approach taken by Comcare in the Tribunal to the construction of this word in the Guide, it is now common ground between the parties that "unable" should not be construed as requiring an activity to be impossible for a person to complete or perform. Rather, the parties submitted, and we accept, the correct construction of "unable" is reflected in the following passage from Leeder v Mayor of Ballarat East [1908] VLR 214 at 223: It is a word not of definite but of flexible meaning. Sometimes, where it is used with reference to a person, it connotes an act or series of acts which no human being could do; sometimes an act or series of acts which the particular person referred to could not in any circumstances do; sometimes an act or series of acts which this person could not in existing circumstances do; and sometimes an act or series of acts which in existing circumstances this person could do if he directed his mind to nothing else, but which, having regard to other circumstances, he could not reasonably be expected to do. It therefore sometimes involves a comparison of the various circumstances influencing action or inaction. (emphasis added) 78 This construction is appropriate when the focus of the Guide is on what a person can and cannot do in going about her or his activities of daily living. It emphasises a pragmatic restriction on the extent to which a person should be expected to push herself or himself before it can be said she or he "is unable" to perform the activity. This includes, in our opinion, circumstances where the level of pain experienced by a person is such that the person cannot reasonably be expected to perform or complete an activity: for a similar approach in relation to the term "difficulty" in the Guide, see Comcare v Moon (2003) 75 ALD 160 at [46]-[49] per Mansfield J. 79 Such a construction is also consistent with the positive verb "can", which is used in the 5% impairment minor criteria in Table 9.7. It is important to recall the context in which these words appear, which is a graduated one from the least to the most severe impairment of lower extremity function. Meanings must be given to the terms used which reflect that gradation. So, in the 5% impairment row of Table 9.7, one of the minor criteria is expressed as "[c]an negotiate three or more stairs or a ramp" (emphasis added). In our opinion, this means that a person in a circumstance faced in her or his daily living, whether inside a house or in public, is able to manage the activity reasonably and without having to apply disproportional effort to perform the activity without an aid or handrail. That is what the context of daily living measured against a normally healthy person implies. It does not imply a person must focus only on whether she or he can mount three or more stairs. 80 The shift from the positive "can" to the negative "unable" between the 5% and 10% minor criteria in Table 9.7 is, in our opinion, not intended to indicate a shift in how much effort or focus a person is expected to apply, but rather to indicate simply that under normal circumstances of daily living a person can manage at least three stairs (5%), or can manage less than three stairs (10%), before needing to reach for or use a handrail or walking aid. As the Tribunal pointed out in its reasons, it is critical (again, paying attention to the context in which these words appear) to recall that "can" and "unable" are both qualified by reference to the use of outside assistance. There is no suggestion that, for example, there are only three stairs that need to be climbed - in daily life, whether inside or outside a home, a person may need to negotiate a flight of stairs which is greater than three in number. The Guide asks a medical assessor to report on, and a decision-maker to determine, whether the person can manage at least three stairs unassisted. It is a practical and pragmatic criterion. 81 Other parts of the Guide support this approach. For example, Table 1.4 on p 26 of the Guide specifies criteria about how far a person can walk before claudication (or cramping) occurs, because of peripheral vascular disease in the lower extremities. The thresholds are set by specifying distances walked, employing language such as "on walking 200 metres or more" and sometimes "on walking more than 75 but less than 100 metres". These expressions are consistent with a construction of using the word "more" when coupled with a number as meaning "at least", and in that sense setting a minimum level of achievement. 82 Similarly, the use of the word "ramp", read in context, clearly suggests the kind of access facility which one finds in daily life as an alternative to stairs. In many public places, as a consequence of increased awareness about proper provision for persons with disabilities or people with young children, ramps are available at or near entrances to buildings as an alternative to stairs. Ramps may also be available for similar reasons in private accommodation or places. All the Guide asks a medical assessor to report on, and a Comcare decision-maker to determine, is whether a person can or cannot manage to negotiate such a ramp unassisted. Once the focus is again retained on these being activities of daily living, it is apparent that the precise kind of stairs or the precise length or gradient of a ramp need not be specified. Indeed, to do so would be counterproductive to the purpose of these assessments because a person is being assessed about her or his capacity to negotiate these obstacles in the range of circumstances she or he may face in her or his daily life - at shops, libraries, hospitals, schools, sports and entertainment facilities, as well as in the home. Requiring too much precision could defeat the breadth of the assessment contemplated by the Guide for certain kinds of injuries. 83 That is why we accept Comcare's submission that the evidence before the Tribunal about Mr Lilley's ability on a treadmill, during a walking test at 4 km/h on a 10 degree gradient, did not provide any relevant evidence for the assessment required by Table 9.7. Neither in structure nor position, nor in length of time spent, does a treadmill resemble or approximate the kind of "ramp" the Guide is intended to deal with. We return to this issue in more detail below when we deal with ground 10 of the amended Notice of Contention. 84 This approach to construction does not result in the absence of any objective standard, nor produce such uncertainty in the result, as to suggest invalidity. The authorities on this question invariably need to be read in their own context, by reference to the statutory language and the factual circumstances there under consideration. For example, in King Gee, the Commissioner for Prices was empowered by the relevant regulation, by order, to "fix and declare the maximum price at which any [declared] goods may be sold generally or in any part of Australia or in any proclaimed area". What the order as promulgated in respect of ready-made garments actually did was to specify a calculation to be made based on the "value" of certain material by reference to country of origin and kind of material, together with taxes, freight costs and the like to be added. Starke J (71 CLR 184 at 192) described the outcome of this process thus: The Prices Order sets the subject a calculation which in the end will not bring out an exact but an approximate result. Averages in quantities and in expenditure must be used involving judgment and experience in the estimation of quantities and the allocation of those quantities and of expenditure in relation to various descriptions and sizes of garments upon which opinions may well differ. In my opinion, that is not fixing or declaring any price within the authority conferred by the Regulations, for the subject cannot certainly ascertain the price that is fixed in respect of any garment manufactured or made by him for sale. 85 Dixon J (at 197) emphasised that any limit on the power must be derived from the statutory language: in that case, phrases such as "fix and declare", "maximum price" and "specified". His Honour concluded: They must, I think, be standards or criteria from which a price may be calculated. It is not enough if the price, or some element entering into its composition, can be obtained only by estimation or by the exercise of judgment or discretion, as, for instance, where apportionment or allocation is required. … It needs no imagination to see that in drafting an order for the fixing of prices for an important trade many difficulties must be encountered and it would be impossible to avoid ambiguities and uncertainties which are bound to arise both from forms of expression and from the intricacies of the subject. But it is not to matters of that sort that I refer. They depend upon the meaning of the instrument and they must be resolved by construction and interpretation as in the case of other documents. They do not go to power. But it is another matter when the basis of the price, however clearly described, involves some matter which is not an ascertainable fact or figure but a matter of estimate, assessment, discretionary allocation, or apportionment, resulting in the attribution of an amount or figure as a matter of judgment. When that is done no certain objective standard is prescribed; it is not a calculation and the result is not a price fixed or a fixed price. That, I think, means that the power has not been pursued and is not well exercised. 86 For present purposes, it is more important to pay attention to the observation of principle by Dixon J in King Gee. His Honour held (at 194, 196) there is no "doctrine" that certainty is a separate requirement that all forms of subordinate legislation must fulfil, a proposition endorsed by Kitto J in Television Corporation Ltd 109 CLR 59 at 71; see also Cann's Pty Ltd 71 CLR 210 at 227. Rather, if uncertainty can be a test of validity it is only because of the nature of the particular rule-making power under consideration, and the "meaning and operation" of the authorising provisions themselves. 87 The point is, uncertainty (which may often be a synonym for lack of precision) is not some kind of freestanding criterion for invalidity. Uncertainty will only invalidate because one can derive from the text, context and purpose of the statute an intention by Parliament that the power be confined in a way which requires a high level of certainty (or precision). That will not always be the case, and in our opinion it is not the case in respect of the Guide. 88 Some of the other authorities referred to by the learned trial judge bear out an approach that certainty as an invalidating criterion depends very much on language and context. In Television Corporation Ltd, the "wide and uncertain" language used in conditions attached by the responsible Minister to a television licence was held expressly by only one justice to invalidate the condition. Kitto J examined what a "condition" on a licence in the particular legislative scheme was intended to mean and held that it meant a "specification of acts to be done or abstained from by the licensee company - a specification telling the company what it is to do or refrain from doing", for the purpose of enabling the Minister to determine, lawfully, whether there is compliance with the condition or not. It was this purposive aspect which led Kitto J to find that the impugned conditions needed to be "reasonably certain" in both expression and operation and that they failed that test because they were too vague. The language used in the conditions was to prohibit licensees from "obstructing, prejudicing or interfering" with four listed kinds of activities by other licensees. Kitto J found that identifying the limits of the conduct subject to the prohibition was impossible. This case illustrates how critical language, statutory context and purpose are to determinations of validity. 89 Dixon J reiterated this in Cann's Pty Ltd 71 CLR 210 at 227-228: The interpretation of all written documents is liable to be attended with difficulty, and it is not my opinion that doubts and misgivings as to what the instrument intends, however heavily they may weigh upon a court of construction, authorize the conclusion that an order made under reg 23 is ultra vires or otherwise void. If in some respects its meaning is unascertainable, then, no doubt, it fails to that extent to prescribe effectively rights or liabilities, but that is because no particular act or thing can be brought within the scope of what is expressed unintelligibly. But to resolve ambiguities and uncertainties about the meaning of any writing is a function of interpretation and, unless the power under which a legislative or administrative order is made is read as requiring certainty of expression as a condition of its valid exercise, as the by-law-making powers of certain corporations have been understood to do, the meaning of the order must be ascertained according to the rules of construction and the principles of interpretation as with any other document. 90 Accordingly we consider the learned trial judge was in error in finding that the criteria for 5% and 10% impairment in Table 9.7 were invalid. That conclusion means the declaration made by the primary judge should be set aside.

Grounds 1, 2 and 3A: construction of "unable" 91 In our opinion, the word "unable" in Table 9.7 imports no sense of impossibility. Rather, as we have said above by reference to Leeder, it is to be construed as meaning what a person cannot manage to do in her or his ordinary activities of daily life, carried out as they are without "superhuman" levels of effort. 92 This construction is borne out by the other contexts in which the word "unable" is used in the Guide. When, in Table 9.14 of the Guide dealing with upper extremity function, a minor criterion is "[u]nable to cut up food", this in context means a person cannot manage in the context of ordinary daily activities to cut up her food. It does not mean that the activity is impossible if she concentrates on nothing but a single attempt to cut up food and can never manage to do so. That would be to take the assessment out of the context of "daily living". Where the Guide intends something more approaching impossibility with the use of a negative word, it says so. For example, also in Table 9.14 is a major criterion at the maximum level of impairment (there, 60%) expressed as "[u]nable to use upper extremity at all". The last two words are textual indicators of a loss of function which is closer to completeness. 93 Until the amended Notice of Contention, there was no challenge in this appeal to the Tribunal's construction and application of the term "unable" in Table 9.7. The challenge had been limited to the use put by the learned trial judge of a more extreme construction of the word as part of his invalidity findings. Neither party supported such a construction. 94 However, ground 3A of the amended Notice of Contention now asserts a construction error in the Tribunal's reasoning. This was developed in argument for the respondent by Mr Thawley SC, by reference to [76] of the Tribunal's reasons, which he submitted needed to be read as informing [42] of the Tribunal's reasons. The former paragraph is in the section of the Tribunal's reasons dealing with the invalidity submission put on behalf of Mr Lilley to the Tribunal and with which we deal below at [102]. 95 Paragraph [42] is the one in which the Tribunal evaluates the weight of Dr Bodel's evidence about whether Mr Lilley met the minor criteria in Table 9.7 at the 10% level of impairment. Dr Bodel found Mr Lilley met the first major criterion at the 10% threshold, but had made a finding as to only one of the minor criteria. However, Dr Le Leu had made a finding that Mr Lilley met the other minor criterion so, when considered together, it was possible for the Tribunal to be satisfied that all criteria were met, if it was inclined on the merits to do so. At [42] the Tribunal states that the language used by Dr Bodel, where he described Mr Lilley's impairment as "has difficulty negotiating stairs without the use of a walking aid or a handrail", was problematic because the language of the Guide was "unable" not "has difficulty". The Tribunal held that Dr Bodel's failure to use the language of the minor criterion "detracted from the value of the assessment he made even in relation to that single criterion". 96 The respondent submitted that, read with [76] of the reasons - where the Tribunal does not advert to the word 'unable" meaning anything less than "cannot perform at all" - as well as the Tribunal's failure to refer to Mr Lilley's own evidence about how he negotiated stairs, the Court should infer that the Tribunal misconstrued this minor criterion by setting the bar too high. 97 We accept that [76] of the Tribunal's reasons, although located in the section of its reasons dealing with submissions on invalidity of the Guide, is dealing with the same expressions in the Guide in the same context and can be read as informing what the Tribunal says at [42]. 98 Given our conclusion on the clinical testing issue, it is not necessary to decide this question because the matter will be remitted to the Tribunal in any event. However, had we needed to decide it, we would not have accepted Mr Thawley's submission that the Tribunal's approach demonstrated a misconstruction of what "unable" means. 99 The word "unable" in Table 9.7 of the Guide should be construed in the way we have set out at [77] above. Read as a whole, the Tribunal's reasons do not demonstrate it adopted any different or erroneous approach. The major criteria at the 5% and 10% level of impairment deliberately use different language. One (5 %) uses the expression "manifest difficulty". The other (10%) uses "unable". As we have said above, the language as well as the subject matter itself is designed to indicate gradations of impairment. It was not suggested to us in argument that these differences in language were explored with Dr Bodel, with a view to laying any evidentiary foundation for a submission that, despite his use of the word "difficulty", his evidence could be taken as supporting a conclusion that Mr Lilley met the major criterion at the 10% level. If this was the sum of the evidence (and it was not suggested otherwise to us) then in our opinion the Tribunal's findings at [42] do not display a misunderstanding of the operation of the Guide. The 5% major criterion relevantly uses the language of "manifest difficulty" (which in itself means more than "difficulty") and the 10% major criterion uses an expression intended to signify lack of ability, with reasonable effort, to do something at all. It was open to the Tribunal to find, as it did, that Dr Bodel's opinion did not support Mr Lilley's claim to meet the 10% threshold on that criterion because he referred to the former concept rather than the latter.

Grounds 3 to 9: a further argument of invalidity 100 The argument supporting these grounds centres on the unreasonableness and lack of proportionality in the criteria specified by the Guide at the 10% whole person impairment level. This was the invalidity argument advanced on behalf of Mr Lilley before the Tribunal. As counsel for the respondent conceded, an invalidity argument of the kind the learned trial judge favoured was not advanced by the respondent before his Honour. 101 In the respondent's submission, the starting point for eligibility (ie at 10%) expressed in the Guide by reference to major and minor criteria is so unreasonable or inconsistent with the enabling purpose (in s 28 of the SRC Act) as to be invalid. The respondent submitted: It was (and is) apparent that the legislation was intended to exclude minor permanent impairments by implementing a threshold of 10%; but it is equally clear from the statutory context that the legislation was designed to compensate for the rest. Delegated legislation which, inconsistently with the pursuit of the enabling purpose, effectively removes a right to compensation for serious (or non-minor) impairment by choosing words which could only be satisfied in exceptional circumstances is not valid. This was the essence of the argument put by Mr Lilley. 102 While we recognise in principle that an attack can be made on subordinate legislation by reference to principles of unreasonableness at least (see South Australia v Tanner (1989) 166 CLR 161; Parker v Minister for Sustainability Environment, Water, Population and Communities (2012) 205 FCR 415 at [62]), we do not consider there is any basis for those criteria in Table 9.7 to be found to be invalid on such grounds. 103 First, we agree with the observations of the learned primary judge that, for such an argument to be properly considered, expert evidence would be necessary in order to establish some evidentiary foundation by which to assess the submission that the criteria as specified at the 10% level are, or are not, reasonable. 104 Second, the challenge seems unduly confined and indeed somewhat opportunistically directed at Mr Lilley's alleged level of impairment. It is not apparent to us (again without the benefit of any expert evidence which might assist in clarifying this) how it can be said that it is only the criteria specified at the 10% level which are so unreasonable as to invalidate the exercise of power, but not the criteria below that or, more importantly, above that. Third, the challenge is only to one set of criteria in one table amongst many hundreds of criteria spread across many tables. Without some kind of comparative exercise (at least across the 10% major and minor criteria throughout the Guide) it seems impossible to determine how these particular criteria are so perverse, irrational or disconnected with the purpose of s 28 of the SRC Act as to be invalid. Finally, since the parties are agreed, and we accept, that the word "unable" as it is used in Table 9.7 and elsewhere in the Guide does not mean "impossible to perform" we consider - again without the benefit of expert evidence - the basis for any asserted invalidity is not apparent.

Ground 10: meaning of "ramp" 105 The respondent submits the Tribunal has failed to complete its statutory task of assessing Mr Lilley's impairment because it did not consider Mr Lilley's ability to use a ramp without hand rails or a walking aid. The assessment of a person's ability to use a ramp, it is submitted, is an alternative to the assessment of a person's ability to use stairs in the minor criteria in Table 9.7. 106 It is true that the word "or" appears in this part of the minor criteria in Table 9.7 of the Guide. It is also true that there is no express consideration in the Tribunal's reasons of Mr Lilley's ability to walk up a ramp. We consider that omission may be explained by the error we have identified in the Tribunal's reasoning process - namely, its insistence on clinical testing. There was no clinical testing of Mr Lilley on a ramp and the Tribunal does not record any opinion by Associate Professor Oakeshott on this matter. To that extent, this ground of appeal adds nothing to the finding of the learned trial judge in respect of the clinical testing issue, with which we agree. 107 Further, as Comcare points out in its supplementary written submissions, the respondent's argument on this ground appears to be related to the failure of the Tribunal to refer in its reasons to the evidence of Dr Lane. Comcare submits: Dr Lane was a vascular surgeon who had, in the course of conducting an angiogram, reported that Mr Lilley developed bilateral compartment syndrome with exercise at 4km/h on a 10 degree gradient, which caused him to develop compartment pain, initially described by Mr Lilley as "4 out of 10", then "7 out of 10" after 2 minutes and 30 seconds and then caused him to stop the activity after 3 minutes and 40 seconds. A treadmill is not a ramp; the development of pain walking at 4km/hour does not equate to an inability to negotiate a ramp, perhaps walking at a slower speed, without the use of a walking aid or hand rails; and walking at 4km/hour for 3 minutes and 40 seconds would cover a 244 metre ramp. This evidence therefore did not deal with the crucial question of whether Mr Lilley was able to walk up and down a ramp, of the kind that would ordinarily be encountered going about ordinary daily activities, without the use of a walking aid or hand rails. As Dr Lane's evidence was incapable of persuading the Tribunal that Mr Lilley met the criteria for a 10% level of impairment, it was not necessary for the Tribunal to refer to it. 108 We accept those submissions. In that sense, any failure to refer to an assessment of Mr Lilley's ability to walk up a ramp was not material to the lawfulness of the Tribunal's decision.

Ground 11: procedural fairness 109 This ground asserts that there was a denial of procedural fairness to Mr Lilley in the Tribunal not disclosing to him its views about the greater weight to be given to evidence based on clinical testing, and to its inclination not to accept aspects of Mr Lilley's evidence unless it was corroborated. It assumes an answer unfavourable to Mr Lilley on the clinical testing ground, which in fact is not the case. 110 In answer to this ground, Comcare submitted in its supplementary submissions: That contention is without merit. The Tribunal did not approach the case on the basis that the medical history given by Mr Lilley to his treating doctors and the Tribunal was irrelevant. It admitted and took into account that evidence, but attached less weight to Mr Lilley's evidence that he could not undertake relevant tasks than it did to Associate Professor Oakeshott's observation of Mr Lilley undertaking those tasks. In any event, as the highlighted passages of the attached transcript of proceedings before the Tribunal make clear, Mr Lilley was on notice that: (a) the weight to be attached to assessments made by doctors without clinical testing; and (b) the absence of corroboration by Mr Lilley's wife of his accounts of problems with stairs and with walking over uneven ground; were an issue; and Mr Lilley could have sought to meet Comcare's criticisms by further evidence or by submissions. Mr Lilley has not explained to the Court what he would have done differently in the Tribunal to address those issues. 111 Having looked at the transcript extracts provided to the Court, we accept Comcare's submissions that Mr Lilley was on notice these matters were in issue. To submit more was required is to insist the Tribunal disclose its reasoning processes, or give a warning of the findings it might be inclined to make on the evidence before it. Its obligation of procedural fairness does not go that far: Lidono Pty Ltd v Federal Commissioner of Taxation (2002) 191 ALR 328 at [20] per Gyles J; Commissioner for Australian Capital Territory Revenue v Alphaone Pty Ltd (1994) 49 FCR 576 at 590-591.

Ground 12: Relief 112 Given our conclusions, it is unnecessary for us to consider the appropriateness of the declaration made by the learned trial judge, as the declaration made will be set aside.

Conclusion and orders 113 We agree with the learned trial judge that the Tribunal's decision is affected by legal error because the Tribunal misconstrued the notes to Table 9.7 as imposing a requirement that there must be "clinical testing" before Mr Lilley could be found to satisfy the criteria for a 10% degree of impairment. Although it may not have been strictly necessary to do so, given this conclusion, we have in any event considered the other arguments put to us in relation to errors in the Tribunal's decision and we have concluded none are made out. 114 We do not agree with the learned trial judge's findings on the invalidity of the criteria in Table 9.7, nor with the respondents' validity argument. Our conclusion on this means the declaration made by his Honour must be set aside. 115 Comcare's appeal was not limited to setting aside the primary judge's declaration in respect of the validity of the impairment tables. Comcare has succeeded in relation to the declaration but the orders made by the primary judge in favour of the respondent have been upheld. The respondent therefore succeeds in his application to have the matter remitted to the Tribunal to be heard and determined according to law. It is an outcome which Comcare unsuccessfully resisted. To reflect those considerations but also to take into account the additional time and resources expended by the appellant in having to respond, without proper notice, to the proposed amended Notice of Contention in circumstances where we have refused leave on most of the new grounds, we consider it is appropriate for the respondent to be awarded only 50% of his costs. 116 Accordingly, the orders of the Court are:

1. Leave is granted to the respondent to amend his Notice of Contention to include ground 3A as it appears in the proposed amended Notice of Contention dated 7 August 2013.
2. Leave to amend the respondent's Notice of Contention is otherwise refused.
3. The appeal be allowed in part.
4. The declaration made by the Court on 25 January 2013 be set aside.
5. The appeal otherwise be dismissed.
6. The appellant pay 50% of the respondent's costs of the appeal, to be taxed in default of agreement. 117 The effect of the Court's orders is that paragraph 2 of the orders of the primary judge remitting the matter to the Tribunal, and paragraphs 3 and 4 dealing with costs, remain in operation. I certify that the preceding one hundred and seventeen (117) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justices Kerr Farrell and Mortimer.