Lilley v Comcare

REASONS FOR JUDGMENT 1 Wayne Lilley became a firefighter in 1988 when he was 20 years old. He was employed by ACT Emergency Services when, on 4 July 2005, he made a compensation claim for a work related injury. That injury was diagnosed as compartment syndrome, which is pain that affects the front and sides of both legs when running and walking. In early 2006 he developed a condition in his left leg related to his compartment syndrome that required surgery. Mr Lilley's left peroneal nerve was damaged as a result of the surgery and subsequent treatment. Comcare accepted liability for both the injuries, namely the compartment syndrome and the damage to the left peroneal nerve. 2 On 12 January 2009, Mr Lilley lodged a claim for permanent impairment of "both lower legs (compartment syndrome) and severed nerve (lower left leg) [and] associated pain/loss of feeling" under s 24 of the Safety Rehabilitation and Compensation Act 1988 (Cth) (the SRC Act). Mr Lilley claimed that that impairment affected his pre-existing type 1 diabetes. Comcare rejected the claim on 20 May 2009 and an internal review affirmed that rejection on 26 February 2010. Mr Lilley sought review of Comcare's decision in the Administrative Appeals Tribunal. On 6 July 2011, the Tribunal affirmed the decision to reject Mr Lilley's claim. 3 Mr Lilley appealed to this Court from the Tribunal's decision under s 44 of the Administrative Appeals Tribunal Act 1975 (Cth) (the AAT Act) and also sought judicial review of that decision under s 5 of the Administrative Decisions (Judicial Review) Act 1977 (Cth) (the ADJR Act) and s 39B of the Judiciary Act 1903 (Cth). In essence, Mr Lilley contended that: (1) the Tribunal misconstrued the requirements of Table 9.7 of the Guide to the Assessment of the Degree of Permanent Impairment (2nd ed) (the Guide) (set out in [7] below), prepared pursuant to s 28(1) of the SRC Act, by holding that the only evidence relevant to assessment of his compartment syndrome was that of medical practitioners who had clinically tested the claimant in respect of the criteria in Table 9.7 and, so he argued, the Tribunal failed to have regard to other medical evidence including opinions based on a history given by Mr Lilley (the evidence issue); (2) the Tribunal erred in construing the minor criterion "is 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 10% impairment category in Table 9.7 by holding that "unable" meant excluding any capacity at all to perform the activity (the construction issue); (3) the 10% impairment category in Table 9.7 was invalid (the invalidity issue).

The Legislative Scheme 4 The SRC Act provided a scheme for payment of compensation by Comcare in respect of an injury suffered by an employee if the injury resulted in death, incapacity for work, or impairment (s 14(1)). "Impairment" was defined as meaning, "the loss, 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" (s 4(1)). Where an injury (relevantly here a physical injury suffered by an employee arising out of, or in the course of, the employee's employment (s 4(1)) resulted in a permanent impairment, s 24(1) required that Comcare pay compensation to the employee in respect of the injury. Relevantly, s 24(5) provided that: "(5) Comcare shall determine the degree of permanent impairment of the employee resulting from an injury under the provisions of the approved Guide." 5 The degree of permanent impairment had to be expressed as a percentage (s 24(6)) and no compensation was payable if Comcare determined that the degree of impairment, relevantly, was less than 10% (s 24(7)). 6 Two tables in the Guide applied to Mr Lilley's injuries. First, Table 9.7 applied to his compartment syndrome. It was headed "Lower Extremity Function". The prefatory notes to Table 9.7 commenced by stating that the table: "should only be used to assess impairment from objectively identified orthopaedic or neurological conditions arising in and affecting the lower extremities. It may not be used to assess impairment from conditions manifesting principally as pain with no clinically demonstrable lower extremity pathology. " After dealing with a number of other issues, the notes explained that the impairment assessed 'is of overall lower extremity function, rather than that of individual extremities'. It concluded by stating: "To fulfil the requirements of a WPI [whole person impairment] 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." (emphasis added) 7 Whole person impairment was a medical quantification of the nature and extent of the effect of the injury or disease on the person's functional capacity, including his or her ordinary daily life activities (see: the Glossary in the Guide p 16). The relevant portions of Table 9.7 were: Table 9.7: Lower Extremity Function % WPI Major Criteria(at least one required) Minor Criteria(at least two required where listed) 0 Walks at a normal pace in comparison with peers on level ground or uneven ground and can avoid obstacles; or Distance walked is not restricted by the condition being assessed (although other factors such as the level of fitness may cause restriction). 5 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. 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). 10 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. 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). 20 Walks at a moderately reduced pace in comparison with peers on level ground; Legs give way occasionally resulting in falls. or Is unable to negotiate three or more stairs or a ramp (up and down) without use of rails.Is unable to rise from sitting to standing position without use of one hand but can stand without support. Walking is restricted to 250m or less at a time (may be able to walk further after resting).

(emphasis added) 8 Secondly, Table 9.6.2a, which was headed "Sensory Impairment due to Peripheral Nerve Injuries Affecting the Lower Extremities", relevantly, provided:

The Tribunal's decision 9 It was common ground before the Tribunal that Mr Lilley's two impairments were permanent. The Tribunal found that the injury to the peroneal nerve caused Mr Lilley to experience numbness in the upper part of his left foot. During 2006 he underwent three operations to address his compartment syndrome, the last in September 2006. However, by February 2007 Mr Lilley was experiencing significant pain in his left foot and outer left lower leg. His outer left lower leg was also hypersensitive to light touch and the upper part of his left foot remained numb. He continued to experience those symptoms at the time of the Tribunal hearing. He had not been able to work as a firefighter since 2005. 10 Mr Lilley complained of experiencing a significant increase in pain symptoms following limited amounts of exertion. The tribunal found that walking for between two to five minutes caused Mr Lilley to experience very severe pain. He underwent treatment for pain management and took medication, inter alia, to assist with the pain. 11 The Tribunal found that Mr Lilley was suffering from two impairments, being the compartment syndrome and the damage to his peroneal nerve. It then turned to consider whether either or both impairments met the minimum threshold of 10% so as to give rise to a right to compensation. 12 The Tribunal noted the medical evidence of three doctors who had assessed Mr Lilley as having either 1% or 2% sensory loss for his peroneal nerve injury under Table 9.6.2a. Of course, 4% was the maximum impairment possible for an injury to that nerve under the table. Mr Lilley conceded that if Table 9.6.2a were validly prescribed pursuant to s 24(5) of the SRC Act then he could not reach the 10% impairment threshold for the injury to the nerve required for eligibility for compensation under s 28(7). 13 The Tribunal then considered whether Mr Lilley's impairment from his compartment syndrome injury reached the minimum threshold. It observed that the notes to Table 9.7 required the integer "manifest difficulty" in the first major criterion of 5% impairment to be clinically tested. The Tribunal then reasoned: "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." (emphasis added) 14 The Tribunal said that the assessments of all the medical practitioners, except for Comcare's expert, Associate Professor Robert Oakeshott, were based on Mr Lilley's history and not independent clinical assessment. The Tribunal found this detracted from the weight it gave to the other medical evidence. 15 The Tribunal summarised the evidence given by Mr Lilley's general practitioner, Dr Rashmi Sharma, an orthopaedic surgeon, Dr James Bodel, an occupational physician, Dr Leon Le Leu and Dr Oakeshott. In essence, Dr Sharma had not assessed Mr Lilley using the Guide but she noted that he was unable to walk for more than five minutes without pain, could not exercise for his diabetes, could not play sport with his children and suffered constant neuropathic pain and numbness in his lower left leg. Dr Bodel assessed Mr Lilley under Table 9.7 as having a 10% impairment. He opined that Mr Lilley satisfied both major criteria. However, Dr Bodel assessed the minor criteria only by stating that Mr Lilley "has difficulty negotiating stairs without use of a walking aid or a handrail". Dr Le Leu found that Mr Lilley satisfied both major criteria for 20% impairment but neither of the minor ones. He opined that Mr Lilley satisfied the second major criterion for 10% impairment and the first minor criterion and that he met all the 5% criteria. 16 The Tribunal recorded Dr Oakeshott's finding that Mr Lilley met the 5% criteria. He had purported to test Mr Lilley by what he said was a walk for over 500 metres without a stop over, at times, uneven ground on a wet path. However, the Tribunal found that Dr Oakeshott's route, in the central business district of Canberra, was only 356 metres long and over flat terrain or paving stones with no more than 1-2 cm disparities. Nonetheless, the Tribunal said: "55. The Tribunal finds, accordingly, that the ground traversed on this occasion, on the available evidence, would not qualify as 'uneven'. 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. That supports the opinion of Associate Professor Oakeshott that Mr Lilley did not meet either of the major criteria for the ten per cent level of assessment nor, it can be assumed from his evidence, did he meet the two minor criteria. His finding that Mr Lilley only met the criteria for the minor criteria for the 5 per cent level is consistent with the conclusions reached in his report." (emphasis added) 17 Dr Oakeshott gave evidence that Mr Lilley had walked down six stairs in a test. The Tribunal preferred his evidence to Mr Lilley's assertion that he had to rely on putting his arm on the wall to enable him to do that. It said that there was no evidence to corroborate Mr Lilley's evidence that he used the handrails on the stairs at his home to walk up and down between storeys. It concluded: "57. … The Tribunal finds that Mr Lilley is capable of walking up and down three or more stairs without the use of a walking aid or personal assistant. The Tribunal has taken a 'walking aid' to include a walking stick or cane, or a walking frame. 58. 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. Nor was there other corroborated evidence to that effect. The Tribunal finds that Mr Lilley cannot meet the minimum threshold of 10 per cent for payment of compensation for his compartment syndrome." (emphasis added) 18 Finally, the Tribunal rejected Mr Lilley's argument that the whole of Tables 9.6.2a and 9.7 were invalid. It held that the percentages used in the tables related to impairment of a body part, system or function to the extent to which it permanently impaired the employee as a whole person. It found that the criteria were not disproportionate or inconsistent with the Act. It found that the tables in the Guide as a whole reflected relativities in relation to the extent of impairment. The Tribunal found that the criteria in Tables 9.6.2a and 9.7 were not so unreasonable or disproportionate as to lead to their invalidity.

Comare's arguments 19 Comcare argued that the Tribunal did not misconstrue the notes to Table 9.7 by excluding medical evidence that did not amount to clinical testing of the matters in the criteria. It referred to the Tribunal's statement that the use of Mr Lilley's history by the practitioners, other than Dr Oakeshott, detracted from the weight it attributed to their evidence. Comcare contended that the Tribunal had not misconstrued the word "unable" in the second minor criterion for 10% impairment by imposing a bright line of complete incapacity. Rather, Comcare submitted, the Tribunal assessed practical ability based on medical evidence. It contended that the words "or more" in the expression "three or more stairs" meant at least three stairs. It argued that the Tribunal's reasons showed that it had regard to the evidence of Dr Bodel and Dr Le Leu. 20 Comcare contended that the medical report of Mr Lilley's treating vascular surgeon, Dr Lane, was incapable of persuading the tribunal that Mr Lilley's condition satisfied the second minor criterion for 10% impairment. Dr Lane's report had stated that Mr Lilley's bilateral compartment syndrome had caused him to stop exercising on a treadmill at 4 kph on a 10 degree gradient while he was undergoing an angiogram. Comcare argued that this report could not be related to the criteria and it was not necessary for the Tribunal to refer to it. 21 Comcare argued that the criteria in Tables 9.6.2a and 9.7 and elsewhere in the Guide were validly made and within the scope of the power in s 28 of the SRC Act. It relied on the decision of the Full Court of the Supreme Court of South Australia in R v Nguyen (2010) 108 SASR 66 to argue that the Tables in the Guide were not invalid for being unreasonable or lacking in proportionality. It contended that the second minor criterion for 10% impairment did not lack certainty and could be applied in a reasonable manner.

Consideration - The evidence issue 22 I am of opinion that the Tribunal misconstrued the notes to Table 9.7 by imposing a requirement that matters other than "manifest difficulty" required clinical testing. There is nothing in the notes to Table 9.7 that imports such a requirement. The criteria in Table 9.7 prescribe factual, as opposed to clinical, conditions. They are descriptive of the effects of an already clinically diagnosed injury. Moreover, as the evidence of Dr Oakeshott showed, it would be impractical for doctors to test some matters, such as walking over uneven ground in city or suburban consulting room environs. 23 It would be entirely adventitious, in the course of a consultation with a medical practitioner, if a claimant could satisfy the first minor criterion for 10% impairment, namely that his or her "legs give way or lock occasionally without resulting falls". How could a claimant be expected, without dissembling, necessarily to satisfy such a requirement on a visit to a doctor, including a scheduled visit to a Comcare doctor? If one's legs give way or lock "occasionally", they do not do so regularly, predictably or necessarily when the person is seeing a doctor. Yet if clinical observation, and not patient history, were necessary or affected the weight of a person's claim to meet this criterion, it is very unlikely that many genuine claimants would be lucky enough to have their legs give way or lock on cue in the course of a clinical consultation. 24 The Tribunal suggested that Mr Lilley needed corroboration for his evidence that he used the stair rails to assist him walking up and down the stairs at home. There was no requirement in the SRC Act or the Guide that a person needed corroboration for his or her evidence. The Tribunal may have been expressing a finding that it did not accept Mr Lilley's uncorroborated evidence or the history he had given to his doctors. That finding may have been open to the Tribunal. However, in [55] of its reasons, the Tribunal used Dr Oakeshott's inept attempt to test Mr Lilley, as clinical evidence that Mr Lilley had not satisfied any of the criteria for 10% impairment. Dr Oakeshott's test was over too short a distance and on even ground. It had nothing to do with the criteria and was irrelevant to any issue before the Tribunal. Dr Oakeshott had been called by Comcare, not Mr Lilley. The evidence of that inept test could not rationally support Dr Oakeshott's opinion that Mr Lilley did not meet any of the criteria for 10% impairment. It was not open to the Tribunal to have made the finding in [55] that that test in fact supported the opinion of Dr Oakeshott. His opinion, so far as it was based on that test, lacked any rational or factual foundation. 25 The Tribunal wrongly took the view that each of the activities of ability to walk and climb stairs and the pace of walking required clinical testing. That was an error of law and imposed a requirement that had no basis in the SRC Act or the Guide. The Tribunal asked itself the wrong question as to the evidence necessary to support a claim for permanent impairment. It constructively failed to exercise its jurisdiction in doing so. It follows that the decision of the Tribunal must be set aside.

Consideration - The construction and invalidity issues 26 The construction and invalidity issues overlap. The source of the power to make the Guide was s 28 of the Act. Importantly s 28 provided: "28 Approved Guide (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. (7) … (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)." 27 As s 28(4) provided, a decision-maker, including the Tribunal, must make or review a decision under the relevant provisions of the Guide. Importantly, s 28(1)(a) and (c) required the Guide to set out criteria by reference to which the degree of permanent impairment, expressed as a percentage, must be determined. Because the Guide is a legislative instrument, the Acts Interpretation Act 1901 (Cth) applies to it as if it were an Act and each of its provisions were a section of an Act as provided by s 13(1) of the Legislative Instruments Act 2003 (Cth). That section provides: "13 Construction of legislative instruments (1) If enabling legislation confers on a rule maker the power to make a legislative instrument, then, unless the contrary intention appears: (a) the Acts Interpretation Act 1901 applies to any legislative instrument so made as if it were an Act and as if each provision of the legislative instrument were a section of an Act; and (b) expressions used in any legislative instrument so made have the same meaning as in the enabling legislation as in force from time to time; and (c) any legislative instrument so made is to be read and construed subject to the enabling legislation as in force from time to time, and so as not to exceed the power of the rule maker. (2) If any legislative instrument would, but for this subsection, be construed as being in excess of the rule maker's power, it is to be taken to be a valid instrument to the extent to which it is not in excess of that power. (3) If enabling legislation confers on a rule maker the power to make a legislative instrument: (a) specifying, declaring or prescribing a matter; or (b) doing anything in relation to a matter; then, in exercising the power, the rule maker may identify the matter by referring to a class or classes of matters. (4) For the purposes of subsection (3), matter includes thing, person and animal. Note: This section has a parallel, in relation to instruments that are not legislative instruments, in subsection 33(3AB) and section 46 of the Acts Interpretation Act 1901." 28 The principles of statutory construction apply to the construction of the Guide by force of s 13(1)(a) of the Legislative Instruments Act; see too Canute v Comcare (2006) 226 CLR 535 at 541 [12] per Gummow A-CJ, Kirby, Callinan, Heydon and Crennan JJ; Collector of Customs v Agfa-Gevaert Ltd (1996) 186 CLR 389 at 398 per Brennan CJ, Dawson, Toohey, Gaudron and McHugh JJ. In Australian Securities & Investments Commission v DB Management Pty Ltd (2000) 199 CLR 321 at 338 [34]-[35] Gleeson CJ, Gaudron, Gummow, Hayne and Callinan JJ said: "In Project Blue Sky Inc v Australian Broadcasting Authority ((1998) 194 CLR 355 at 384, per McHugh, Gummow, Kirby and Hayne JJ), after pointing out that the duty of a court is to give the words of a statutory provision the meaning that the legislature is taken to have intended them to have, the majority said: "Ordinarily, that meaning (the legal meaning) will correspond with the grammatical meaning of the provision. But not always. The context of the words, the consequences of a literal or grammatical construction, the purpose of the statute or the canons of construction may require the words of a legislative provision to be read in a way that does not correspond with the literal or grammatical meaning." It may be added that, if a party contends that a provision, by reason of such considerations, should not be given its literal meaning, then such a contention may lack force unless accompanied by some plausible formulation of an alternative legal meaning." 29 The power to make a criterion in the Guide must be exercised in a way that sets an objective standard that may be applied with certainty and mechanically or measurably. The power to prescribe a criterion cannot be used to confer on a third party, such as a doctor or decision-maker a wide and unreviewable discretion to determine the standard against which a particular claimant's impairment is to be measured. That is because the function of prescribing a criterion is itself to set, not delegate the setting of, the standard. The criterion must be so expressed that whoever applies it will arrive at the same result, if he or she uses it correctly: Racecourse Co-operative Sugar Association Ltd v Attorney-General (Qld) (1979) 142 CLR 460 at 480-481 per Gibbs J with whom Stephen, Mason and Wilson JJ agreed. Gibbs J drew on what Dixon J had said in King Gee Clothing Co Pty Ltd v The Commonwealth (1945) 71 CLR 184 at 197, namely: "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." 30 The result, in such a situation, is that the power to make the criterion has not been validly exercised, and accordingly, the criterion was made in excess of the rule-maker's power. This is not because the meaning of the criterion is uncertain. Rather, it is because the criterion as expressed creates uncertainty in the result it produces: Cann's Pty Ltd v The Commonwealth (1946) 71 CLR 210 at 228 per Dixon J; see too Television Corporation Ltd v The Commonwealth (1963) 109 CLR 59 at 71 per Kitto J and my discussion of the principles in Telstra Corporation Ltd v Australian Competition and Consumer Commission (2008) 176 FCR 153 at 193-194 [159]-[161]. 31 The ordinary and natural meaning of "criterion" as used in s 28 of the SRC Act is: an established rule or principle for testing anything (Macquarie Dictionary online) a test, principle, rule, canon or standard by which anything is judged or estimated (Oxford English Dictionary online) 32 In Herald-Sun TV Pty Ltd v Australian Broadcasting Tribunal (1985) 156 CLR 1 at 4 Gibbs CJ, Mason, Wilson, Deane and Dawson JJ discussed a power in an Act to set a standard for television programs saying: "A standard determined for a television programme must fix the quality or nature of the programme in such a way that both the licensee required to observe the standard and the court or other body called upon to decide whether it has done so can determine whether the programme answers the criteria set by the standard. That is not to say that the test should be entirely objective, for it may involve questions of taste, but it does mean that the standard is to be found in the determination itself. The power to fix a standard which is to be generally applied is quite different from a power to decide ad hoc, from case to case, whether a particular programme may be televised. A power of the latter kind is not a power to fix standards." (emphasis added) 33 The immediate difficulty is to determine any intelligible, certain meaning for the second minor criteria for 5% and 10% impairment. The former requires that the claimant "can", while the later requires he or she "is unable to", "negotiate three or more stairs or a ramp (up and down) without the use of a walking aid or hand rails". 34 First, it is impossible to understand any rational concept in the 5% criterion reflective of an impairment. If a person can meet that criterion, he or she would seem to be quite unimpaired. The criterion is self-evidently not reflective of any measure of impairment and is a nonsense. Secondly, the expressions "three or more stairs" and "a ramp" have no content. Comcare argued that the words "or more" meant "at least" and the ramp had to be a reasonable ramp of the kind ordinarily encountered. 35 I reject that argument. A person may not be able to walk up or down a flight of stairs between storeys at his or her home or in the course of his or her ordinary activities, without the use of a walking aid or hand rails, but may be able to negotiate one, two or three stairs without that assistance. The words "or more" must have been intended to capture such a situation. However, once a person can negotiate three stairs without the use of a walking aid or hand rail, even though he or she cannot negotiate a longer flight of stairs, he or she does not satisfy the criterion. 36 Thirdly, the dimensions and gradient of the "ramp" are, like the "or more stairs" entirely unspecified. When a claimant is required to negotiate a ramp, it is not clear what characteristics the ramp must have. There was no evidence of universal standards or lengths for ramps. Often, in workplaces there will be ramps of varying inclinations and lengths, purpose built for the particular requirements of the employer. Similarly, in public places ramps can have various gradients, although there may be maximum gradients. However, a claimant may have to deal with a particular type of ramp of a particular length or inclination in his or her daily life or work. Fourthly, the words "is unable to" in the 10% criterion, particularly when contrasted with "can" in the 5% criterion, suggest complete inability. That reinforces the suggestion that if the claimant can pass the third stair he or she is not "unable to" negotiate three stairs, even if he fails at the fourth or a later stair. 37 The word "unable" means "not able, not having ability or power to perform … something specified" (Oxford English Dictionary online). When juxtaposed with "can" as used in the 5% minor criterion, I am satisfied that "unable" when used in the succeeding percentage minor criteria means not having the ability or power to negotiate the number of stairs or ramp unless the person uses the specified means of external assistance. The word "unable" has the same meaning when it is used in the first major criterion for 10% impairment. That is, the person has the ability to perform the task (negotiating uneven ground, three or more stairs or a ramp) only with the external assistance. The consequence is that no matter how difficult it is or how long it takes, if the person has the ability to perform that task without external assistance, he or she cannot satisfy the relevant criterion. Thus, a person who takes 10 minutes to walk up three stairs without using an external means to assist him or her, cannot satisfy the criterion because he or she has the ability to do so, notwithstanding the obvious and substantial impairment of that ability. He or she is not "unable". The use of the qualification of "without" a form of external assistance demonstrates that Table 9.7 does not contemplate some other qualification to the ordinary meaning of "unable" to bring within it a situation of the successful 10 minute struggle to negotiate the three stairs unaided. 38 As I have explained above, I do not consider that the words "or more", in describing the number of stairs, can be read as meaning "at least", because both "or more" and "at least" would be unnecessary surplusage if the criterion had been intended to prescribe simply three stairs. Rather by leaving open the relevant number of stairs, and the description of the characteristics of the ramp, the criterion gave the decision-maker a discretion as to the nature and extent of the task, being no less than three stairs or a ramp the inclination and length of which the decision-maker was free to decide, which the claimant had to demonstrate that he or she was unable to perform. 39 The issue is whether the power to prescribe the criteria in the Guide permitted the creation of a discretion in the decision-maker to select the number of stairs or particular ramp that the claimant had to be unable to negotiate without using the specified external assistance. 40 I am of opinion that Table 9.7 does not fix an objective standard for the number of stairs or characteristics of the ramp that a claimant must be unable to negotiate without use of an external aid. Rather, it leaves to the decision-maker the unfettered power to determine whether more than three steps will suffice, and then how many or what particular ramp must be negotiated. That discretion is not within the concept of a criterion because it leaves to the decision-maker an ad hoc power to decide from case to case as to whether some particular number of stairs or some particular ramp is, or is not, the yardstick by which to measure the claimant's ability or lack of ability: Racecourse Co-operative 142 CLR at 480-481; Herald-Sun 156 CLR at 4; Television Corporation 109 CLR at 71; Telstra 176 FCR at 193-194 [159]-[161]. Accordingly, the criteria for 5% and 10% impairment Table 9.7 are invalid since they cannot operate without two minimum criteria. 41 This makes it unnecessary to consider the proportionality argument. As I pointed out during the course of oral argument, it would be difficult to assess that argument without the benefit of expert evidence as to the appropriateness of the criteria that are challenged. The SRC Act only adopts the "whole person impairment" approach with respect to permanent impairments resulting from each "injury": Canute 226 CLR at 548 [37]. The appropriateness of the percentage assessment of the relative degree of impairment from a particular injury selected in the Guide is not readily susceptible of evaluation without expert evidence.

Conclusion 42 For these reasons, the appeal under s 44 of the AAT Act must be allowed and the decision of the Tribunal set aside. The matter will be remitted to the Tribunal to be heard and determined according to law. I will also make a declaration as to the invalidity of the 5% and 10% criteria in Table 9.7. I certify that the preceding forty-two (42) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Rares.