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.