Woods v Northern Territory of Australia - [2024] NTCA 9

CITATION:Woods v Northern Territory of Australia [2024] NTCA 9
PARTIES:WOODS, Denese
v

NORTHERN TERRITORY OF AUSTRALIA

TITLE OF COURT:  COURT OF APPEAL OF THE NORTHERN TERRITORY
JURISDICTION:  CIVIL APPEAL from the SUPREME COURT exercising Territory jurisdiction
FILE NO:AP 6 of 2024 (22418099)
DELIVERED:  18 December 2024
HEARING DATE:  25 November 2024
JUDGMENT OF:  Grant CJ, Kelly and Brownhill JJ
CATCHWORDS:

WORKERS COMPENSATION – Appeal – Whether the Supreme Court erred in construing and applying the Act and the Guidelines – Assessment of compensation payable where worker has two injuries – Deductions for pre-existing conditions or injuries – Impairments arising from more than one injury – Whether a ‘whole person impairment’ approach or an ‘injury by injury’ approach should be applied – Language of the Act presents a constructional choice – Constructional choice to be made with reference to the scheme of the Act and the objects or policies of that Act – Centrality of ‘injury’ in the Act points towards an ‘injury by injury’ approach – Absence of any provisions addressing ‘double dipping’ point against a ‘whole of person’ approach – Intention that nationally developed Guidelines are to operate points towards an ‘injury by injury’ approach – Appeal dismissed.
Allianz Australia Insurance Ltd v Territory Insurance Office (2008) 23 NTLR 186, Attorney-General (NT) v Chaffey (2007) 231 CLR 651, Canute v Comcare (2006) 226 CLR 535, Cooper Brookes (Wollongong) Pty Ltd v Federal Commissioner of Taxation (1981) 147 CLR 297, Esso Australia Resources Ltd v Commissioner of Taxation (1998) 83 FCR 511, Federal Commissioner of Taxation v Smorgon (1977) 16 ALR 721, Lee v McMahon Contractors Pty Ltd (2018) 41 NTLR 168, Northern Territory of Australia v Pengilly (2004) NTLR 18, Public Transport Commission of NSW v J Murray-More (NSW) Pty Ltd (1975) 132 CLR 336, R v Independent Broad-Based Anti-corruption Commissioner (2016) 256 CLR 459, SAS Trustee Corporation v Miles (2018) 265 CLR 137, Victims Compensation Fund Corporation v Brown (2003) 77 ALJR 1797, Victoria v The Queen [2014] FSCA 311, Yuendumu Social Club Inc v Day & Anor [2010] NTSC 22, referred to.
Interpretation Act 1978 (NT) ss 24, 61, 62A
Return to Work Act 1986 (NT) ss 3, 3A, 52, 53, 62, 64, 65, 70, 71, 72, 126A
Return to Work Regulations 1986 (NT)
Northern Territory WorkSafe Guidelines for the Evaluation of Permanent Impairment paragraphs 1.27, 1.28, 1.63, 11.10

D Pearce, Statutory Interpretation in Australia, 9^th edition

REPRESENTATION:
Counsel:
Appellant:D McConnel SC, with C Heske
Respondent:  JW Roper SC
Solicitors:
Appellant:Halfpennys Lawyers
Respondent:  Finlaysons Lawyers
Judgment category classification:    B
Number of pages:  35

IN THE SUPREME COURT
OF THE NORTHERN TERRITORY
OF AUSTRALIA
AT DARWIN
Woods v Northern Territory of Australia [2024] NTCA 9

No. AP 6 of 2024 (22418099)
BETWEEN:

DENESE WOODS

Appellant

AND:

NORTHERN TERRITORY OF AUSTRALIA

Respondent

CORAM: GRANT CJ, KELLY & BROWNHILL JJ
REASONS FOR JUDGMENT
(Delivered 18 December 2024)
Introduction

This is an appeal from a decision of the Supreme Court dismissing an appeal from the Work Health Court.[1]
The sole ground of appeal is that the Supreme Court erred on a question of law in wrongly construing s 71 of the Return to Work Act 1986 (NT) (‘Act’) and the Northern Territory WorkSafe Guidelines for the Evaluation of Permanent Impairment (‘Guidelines’) by finding (at [49]) that on the face of the relevant provisions of the Guidelines they do not distinguish between compensable injuries and non-compensable injuries such that it was necessary to make a deduction for the impairment caused by the first injury notwithstanding that it was, as between the parties, a compensable injury.
Background
This summary of the background to this appeal is largely taken from the Reasons of the Supreme Court.[2]
The appellant worked as a school teacher with the Northern Territory Department of Education at two schools. She was a ‘worker’ as defined in the Act. It was claimed that in the course of her employment the appellant was exposed to traumatic and violent interactions with students which substantially contributed to her sustaining psychological injuries.
The first such injury occurred when she worked as a teacher at the Katherine High School. It was agreed that, on 21 February 2017, the appellant sustained a ‘mental injury’ during the course of her employment (‘first injury’). She received benefits payable under the Act until returning to full-time duties in about March 2017. Thereafter, the appellant sustained a further ‘mental injury’ in the course of her employment whilst working at the Palmerston College on 22 June 2020 (‘second injury’). Liability for the second injury was initially disputed.
The parties agreed that, on 24 August 2020, the appellant served on the respondent a permanent impairment assessment report by a psychiatrist, Dr Takyar (‘Dr Takyar’s first report’), which assessed the appellant’s whole person impairment (‘WPI’): (a) referable to the first injury at 11%; and (b) referable to the second injury at 11%.
On request and pursuant to the legislation, this report was referred to the Work Health Authority under the Act for a panel assessment. On 5 February 2021, the Panel Report was issued to the parties and this assessed the appellant’s WPI: (a) referable to the first injury at 5%; and (b) referable to the second injury at 12%. At the time of the Panel Report, liability for the second injury had not been accepted by the respondent for the purposes of the Act. Accordingly, the second injury should not have been dealt with in Dr Takyar’s first report or the subject of a referral to a panel, and those assessments are of no legal effect.
On 1 March 2021, the respondent wrote to the appellant confirming that payment in relation to the first injury would be made but denying liability in relation to the assessment by the panel of 12% for the second injury. On 7 April 2021, the respondent paid $7,078.66 to the appellant in respect of the 5% WPI assessment referable to the first injury.
On 10 December 2021, the respondent accepted liability for the second injury and, on 13 December 2021, the appellant’s Work Health Court proceedings in relation to that injury were resolved by way of a consent order.
A further report dated 3 May 2022 was obtained from Dr Takyar (‘Dr Takyar’s second report’) in which he assessed the appellant’s WPI: (a) referable to the first injury at 9%; and (b) referable to the second injury at 13%.
On 15 June 2022, without admission, the respondent paid the appellant $28,208.12 in respect of the 13% WPI assessment referable to the second injury.
The Work Health Court decision
The issue before the Work Health Court which was the subject of the appeal to the Supreme Court was identified by the parties to be the nature of the first injury and the second injury and whether, for permanent impairment assessment purposes, the first injury and the second injury gave rise to the one impairment.
The Work Health Court provided detailed written reasons for concluding that the respondent had paid permanent impairment compensation to the appellant in relation to both the first injury and the second injury before the commencement of the Work Health Court proceeding and had therefore acquitted its liability under the Act in relation to the appellant’s entitlement to compensation for permanent impairment.[3]
As appears in the decision of the Work Health Court, the appellant had essentially contended that compensation for permanent impairment is founded upon permanent disability, not injury; the respondent was solely liable to compensate the appellant for the single total degree of permanent impairment suffered as a consequence of the two separate injuries (ie, the 22% WPI), with a deduction for the amount of compensation already paid to the appellant for permanent impairment in respect of the first injury; and the separate assessment of the appellant’s permanent impairment by reference to each injury constitutes an incorrect application of paragraphs 1.6.3 and 11.10 of the Guidelines because deductions of pre-existing impairment levels are limited to pre-existing non-compensable impairments.
The respondent had essentially contended that the entitlement to compensation for permanent impairment under the Act is predicated upon that impairment being caused by a compensable injury; and where there were two separate compensable injuries, the Guidelines require that there be apportionment of the permanent impairment as between each injury, such that, in respect of the appellant’s claim relating to the second injury, the respondent was only liable to pay compensation for the 13% WPI attributable to the second injury.
There was also an issue about whether Dr Takyar’s first report had any operative effect, which is of no present relevance.
The Work Health Court held (at [48]) that there were two injuries; the first injury is a pre-existing injury to the second injury; and under paragraphs 1.28, 11.10 and 1.6.3 of the Guidelines, the assessment of the degree of permanent impairment applicable to the second injury was required to, and did, identify and then deduct the degree of impairment caused by the first injury.
The respondent was held to have paid permanent impairment compensation to the appellant in respect of both the first injury and the second injury prior to commencement of the proceeding.
The appeal to the Supreme Court
The appellant appealed to the Supreme Court on the ground that the Work Health Court had erred in construing the Act and the Guidelines to require the degree of permanent impairment caused by the first injury to be deducted from the assessment of permanent impairment relating to the second injury, which led to a determination that the appellant had received her full entitlement to compensation under the Act.[4]
The Supreme Court dismissed the appeal, holding that there had been no error in the Work Health Court’s construction of the Act and the Guidelines.
The appeal to this Court
The appellant appealed to this Court, on the ground identified above, which was essentially the same ground as was dismissed by the Supreme Court.
The legislative scheme
The Act
The long title to the Act is: ‘An Act about workers’ rehabilitation and compensation’.
Part 5 of the Act deals with compensation and rehabilitation.
Section 52(1) of the Act provides that no action for damages in favour of (relevantly) a worker shall lie against (relevantly) the employer of the worker in respect of: (i) an injury to the worker; or (ii) the death of the worker as a result of or materially contributed to by an injury. Section 52(3) provides that, except as provided by the Act, no action for compensation or a benefit of any kind by (relevantly) a worker shall lie against the employer of the worker in respect of: (i) an injury to the worker; or (ii) the death of the worker as a result of or materially contributed to by an injury.
Section 53 is headed ‘Compensation in respect of injuries’. Section 53(1) provides that, if a worker suffers an injury and that injury results in or materially contributes to his or her death, impairment or incapacity, there is payable by his or her employer to the worker or the worker’s dependants, in accordance with Part 5, such compensation as is prescribed.
Section 53 is the primary provision under which compensation is payable to workers under the Act. It is clear from s 53(1) that compensation is payable under the Act in respect of injuries that result in or materially contribute to the worker’s death, impairment or incapacity. The touchstone for the entitlement to compensation under the Act is that a worker suffers an injury, not that they suffer an impairment.[5]
Division 3 of Part 5 deals with the amount of compensation payable to a worker in respect of an injury under the Act.
Subdivision AA sets out limits on the compensation payable. Subdivision A deals with the amount of compensation payable where the death of a worker results from or is materially contributed to by an injury (s 62(1)). Subdivision B deals with the amount of compensation payable where the worker is totally or partially incapacitated for work as the result of an injury (ss 64(1), 65(1)).
Subdivision C deals with the amount of compensation payable to a worker who suffers permanent impairment.
Section 71(1) provides that a worker who suffers permanent impairment assessed at a percentage of the whole person equal to not less than 15% shall be paid compensation equal to that assessed percentage of 208 times average weekly earnings at the time the payment is made.
Section 71(2) provides that a worker who suffers permanent impairment assessed at not less than 85% of the whole person shall be paid compensation of 208 times average weekly earnings at the time the payment is made.
Section 71(3) provides that where a worker suffers permanent impairment assessed at a percentage of the whole person equal to less than 15%, the worker shall be paid compensation equal to the relevant percentage specified in the Table applicable to the assessed percentage of permanent impairment of 208 times average weekly earnings. The Table provides that for WPI of 5% to less than 10%, the specified percentage is 2%; for WPI of 10%, the specified percentage is 3%; for WPI of 11%, the specified percentage is 4%; for WPI of 12%, the specified percentage is 6%; for WPI of 13%, the specified percentage is 8%; and for WPI of 14%, the specified percentage is 12%.
‘Permanent impairment’ is defined to mean an impairment or impairments assessed, in accordance with the guides approved and published by the Authority, as being an impairment, or combination of impairments, of not less than 5% of the whole person (s 70).
‘Impairment’ is defined to mean a bodily or mental abnormality or loss caused by an injury (s 3).
An ‘injury’ is defined to mean a physical or mental injury arising out of or in the course of the worker’s employment, and includes (relevantly) the aggravation, acceleration, exacerbation, recurrence or deterioration of a pre-existing injury (s 3A(1)).
The level of permanent impairment for the purposes of s 71 is to be assessed in the first instance by a medical practitioner (s 72(2)). Where a person is aggrieved by the assessment of the medical practitioner the person may, within 28 days after being notified of the assessment, apply to the Work Health Authority for a reassessment of that level (s 72(3)). The Authority must then refer the application to a panel of three medical practitioners to reassess the level of permanent impairment (s 72(3A)). The Authority is not required to refer an application to a panel unless satisfied that the assessment is properly conducted and is in accordance with the guides mentioned in s 70 (s 72(3B)). The assessment made by the panel is taken to be the level of permanent impairment suffered by the worker and is not subject to review (s 72(4)).
Compensation is to be paid to the worker: (a) if no application is made for reassessment, not later than 14 days after the end of the 28 day period allowed for that application; or (b) if an application is made for a reassessment, not later than 28 days after the applicant is notified of the reassessment (s 71(4)).
The Guidelines
The reference in s 70 to the guides approved and published by the Authority is a reference to the Guidelines.
The introduction to the Guidelines contains what is described as a basic summary of some key principles of permanent impairment assessments, which include that assessing permanent impairment involves clinical assessment of the claimant as they present on the day of assessment taking into account their relevant medical history and all available relevant medical information in order to determine (relevantly) ([1.6.1]):
·    whether the claimant’s compensable injury/condition has resulted in an impairment;
·    the degree of permanent impairment that results from the injury; and
·    the proportion of permanent impairment due to any previous injury, pre-existing condition or abnormality, if any, in accordance with diagnostic and other objective criteria as outlined in the Guidelines.
Another key principle is that assessors are required to exercise their clinical judgement in determining a diagnosis when assessing permanent impairment and when making deductions for pre-existing injuries/conditions ([1.6.2]).
Another key principle is that, in calculating the final level of impairment, the assessor needs to clarify the degree of impairment that results from the compensable injury/condition, and any deductions for pre-existing injuries/conditions are to be clearly identified in the report and calculated ([1.6.3]).
Paragraphs 1.27 and 1.28 deal with the issue of deductions for pre-existing conditions or injuries, as follows:
1.27 The degree of permanent impairment resulting from pre-existing impairments should not be included in the final calculation of permanent impairment if those impairments are not related to the compensable injury. The assessor needs to take account of all available evidence to calculate the degree of permanent impairment that pre-existed the injury.
1.28 In assessing the degree of permanent impairment resulting from the compensable injury/condition, the assessor is to indicate the degree of impairment due to any previous injury, pre-existing condition or abnormality. This proportion is known as “the deductible proportion” and should be deducted from the degree of permanent impairment determined by the assessor.
Further, impairments that result from more than one injury arising out of the same incident are to be assessed together to calculate the degree of permanent impairment of the claimant ([1.17]).
Also relevant is paragraph 11.10, which relates particularly to psychiatric and psychological disorders and provides:
To measure the impairment caused by a work-related injury or incident, the psychiatrist must measure the proportion of WPI due to a pre-existing condition. Pre-existing impairment is calculated using the same method for calculating current impairment level. The assessing psychiatrist uses all available information to rate the injured worker’s pre-injury level of functioning in each of the areas of function. The percentage impairment is calculated using the aggregate score and median class score using the conversion table below. The injured worker’s current level of impairment is then assessed, and the pre-existing impairment level (%) is then subtracted from their current level to obtain the percentage of permanent impairment directly attributable to the work-related injury. If the percentage of pre-existing impairment cannot be assessed, the deduction is 1/10th of the assessed WPI.
The alternative constructions of s 71
The appellant argued that s 71 of the Act entitles a worker to compensation calculated by reference to their degree of permanent impairment on the day of the assessment, regardless of whether that degree has been caused or contributed to by one injury or more than one injuries, whenever sustained, and regardless of whether the worker has been previously paid compensation in respect of the previous injury or injuries, including for the degree of permanent impairment resulting therefrom. This construction may conveniently be described as ‘a whole person approach’ to compensation for permanent impairment.
The respondent argued that s 71 entitles a worker to compensation calculated by reference to only the degree of permanent impairment caused or contributed to by the particular injury or injuries that gave rise to the claim, and not to any degree of permanent impairment caused or contributed to by any previous injuries. This construction may conveniently be described as ‘an injury by injury approach’, or perhaps more accurately as ‘an incident by incident’ or ‘claim by claim’ approach, to compensation for permanent impairment.
On their face, and as held by the Work Health Court and the Supreme Court, the Guidelines are drafted on the basis that s 71 is construed as the respondent has argued. The appellant argued that the Guidelines are inconsistent with s 71 and, in accordance with s 61 of the Interpretation Act 1978 (NT), must be ‘read down’ to ensure their validity, which would require:
(a)those parts which require a deduction from the degree of permanent impairment referable to previous injuries (such as paragraphs 1.6.3, 1.27, 1.28 and 11.10) to be severed from the Guidelines; or
(b)those parts to be construed as referring only to ‘non-compensable injuries’, ie injuries that did not arise out of or in the course of employment and are not ‘injuries’ within the meaning of the Act.

The language of s 71 (incorporating the relevant definitions) presents a constructional choice[6] and the choice ultimately turns on an evaluation of the relative coherence of each with the scheme of the Act and its identified objects or policies, on the understanding that a legislature ordinarily intends to pursue its purposes by coherent means.[7]
Textual and contextual indications
It follows, both from the definition of ‘impairment’ and the context in which s 71 appears (as set out in paragraphs 23 to 37 above), that the entitlement to compensation under s 71 rests on the worker sustaining an injury which causes impairment.
In Lee v McMahon Contractors Pty Ltd (2018) 41 NTLR 168, the Northern Territory Court of Appeal applied in relation to the Act (at [23]) the following observations of Gummow ACJ, Kirby, Callinan, Heydon and Crennan JJ in Canute v Comcare (2006) 226 CLR 535 (at [10]) regarding the definition of ‘injury’ in the Safety, Rehabilitation and Compensation Act 1988 (Cth):
...[T]hree things may be observed about the concept of ‘an injury’. First, the Act does not oblige Comcare to pay compensation in respect of an employee’s impairment; it is liable to pay compensation in respect of ‘the injury’. Secondly, the term ‘injury’ is not used in the Act in the sense of ‘workplace accident’. The definition of ‘injury’ is expressed in terms of the resultant effect of an incident or ailment upon the employee’s body. Thirdly, the term ‘injury’ is not used in a global sense to describe the general condition of the employee following an incident. The Act refers disjunctively to ‘disease’ or ‘physical or mental’ injuries and, at least to that extent, it assumes that an employee may sustain more than one ‘injury’. The use in s 24(1) of the indefinite article in the expression ‘an injury’ reinforces that conclusion.
Section 24(1) of the Commonwealth Act provided that, where an injury to an employee results in a permanent impairment, Comcare is liable to pay compensation to the employee in respect of the injury. The term ‘injury’ was defined in similar terms to the definition in the Act. The term ‘impairment’ was defined in less similar terms to the definition in the Act, but the High Court’s observations (at [11]) about that term also appear apt to the Act:
The definition of ‘impairment’ (and by extension the concept of ‘permanent impairment’) is expressed in terms of effects on bodily parts, systems and functions. This disaggregated sense of the word is reinforced by the use of the indefinite expression ‘a permanent impairment’ in s 24(1). Textually, the Act assumes that ‘an injury’ may result in more than one ‘impairment’.
The Act does not have that textual reinforcement, but it is clear from the definition of ‘permanent impairment’ in s 70 that an injury may result in more than one impairment.
If it be accepted that the High Court’s observations about the provision entitling an employee to compensation for permanent impairment and its foundational terms in the Commonwealth Act are apt to s 71 and its foundational terms in the Act, some guidance about the operation of s 71 may be found in the following observations of the High Court (at [15]):
The scheme of the Act proceeds ... from the occurrence of ‘an injury’, in the defined sense. As previously remarked, the Act assumes that more than one ‘injury’ may occur. Therefore it is not correct to say that s 24(5) [which provides that Comcare is to determine the degree of permanent impairment resulting from an injury in accordance with the Guides] imports a ‘whole person’ approach to the determination of the degree of permanent impairment. That ignores the centrality of ‘an injury’ to the scheme upon which Comcare’s liability to compensation depends.
These observations fit with the proposition that the entitlement to compensation under s 71 rests on the worker sustaining an injury (ie, the resultant effect of an incident or ailment upon the worker’s body) which causes impairment (a bodily or mental abnormality or loss). The centrality of an injury to the employer’s liability to pay compensation under the Act, as confirmed by the fact that compensation is payable ‘in respect of an injury’, points against a ‘whole of person’ approach to the compensation for permanent impairment in s 71.
Singular includes the plural
The constructional choice is not necessarily resolved by consideration of the use of the singular reference to ‘injury’ in the definition of ‘impairment’ because:
(a)the definition of ‘permanent impairment’ refers to an impairment or combination of impairments, which would capture the situation where a worker’s degree of permanent impairment is comprised from multiple impairments caused by a single injury; and
(b)unless a contrary intention appears, the singular reference to ‘injury’ in the definition of ‘impairment’ includes the plural,[8] so the definition of ‘permanent impairment’ would capture the situation where a worker’s degree of permanent impairment is comprised from a single impairment caused by more than one injury.
Harsh, capricious or unjust
The appellant argued that the respondent’s construction of s 71 would yield an outcome which is ‘harsh, capricious or unjust’ for a worker who has a current permanent impairment of 15% or more of the whole person, which is the result of two separate injuries each contributing less than 15% of the whole person. If the permanent impairment is compensated by separating the two components because they are each referable to a different injury sustained at different times, the effect of s 71(3) is that the worker would be entitled to significantly less compensation for the current permanent impairment to which both injuries have contributed. This, coupled with the characterisation of the Act as ‘beneficial legislation’ and the purposive approach required by s 62A of the Interpretation Act 1978 (NT), was argued to require that the appellant’s construction be adopted.
It appears that the appellant was describing, by way of a gloss, the approach to statutory construction of taking into account the consequences of giving a particular meaning to a provision and the principle within this approach to the effect that, if one construction will do manifest injustice and the other avoid it, the latter construction should be adopted.[9] This has been expressed variously as: ‘where two meanings are open...it is proper to adopt that meaning that will avoid consequences that appear irrational and unjust’;[10] ‘a construction of a statute which interferes with the legal rights of a subject to a lesser extent and produces the less hardship is to be preferred to another, having the opposite effect’;[11] and ‘statutory text [must] be examined to see if it allows for an interpretive choice which avoids manifest unfairness, legislative redundancy and expropriation of vested rights’.[12]
As Mason and Wilson JJ observed in Cooper Brooks (Wollongong) Pty Ltd v Federal Commissioner of Taxation (1981) 147 CLR 297 (at 320-321), the fundamental object of statutory construction in every case is to ascertain the legislative intention by reference to the language of the instrument viewed as a whole. In performing that task, the courts look to the operation of the statute according to its terms and to legitimate aids to construction, the rules of which are no more than rules of common sense designed to achieve this object. When a court labels the operation of the statute as ‘absurd’, ‘extraordinary’, ‘capricious’, ‘irrational’ or ‘obscure’, it assigns a ground for concluding that the legislature could not have intended such an operation and that an alternative interpretation must be preferred. The propriety of departing from the literal interpretation is not confined to situations described by these labels and extends to any situation in which for good reason the operation of the statute on a literal reading does not conform to the legislative intent as ascertained from the provisions of the statute, including the policy intent which may be discerned from those provisions. If the choice is between two strongly competing interpretations, the advantage may lie with that which produces the fairer and more convenient operation so long as it conforms to the legislative intention.
However, as explained in Esso Australia Resources Ltd v Federal Commissioner of Taxation (1998) 83 FCR 511, when different views can be held about whether the consequence is anomalous on the one hand or acceptable or understandable on the other, the court should be particularly careful that arguments based on anomaly or incongruity are not allowed to obscure the real intention, and choice, of the parliament.[13]
As Gageler J observed in R v Independent Broad-Based Anti-corruption Commissioner (2016) 256 CLR 459 (at [76]):
Legislation is sometimes harsh. It is rarely incoherent. It should not be reduced to incoherence by judicial construction.
Reliance was placed by the appellant on the observations in Yuendumu Social Club Inc v Day [2010] NTSC 22 (at [14]) that the Act is a remedial statute and accordingly its provisions should be interpreted in a benign and liberal manner such that a construction most favourable to the worker is to be preferred where any ambiguity exists.
The appellant did not argue that there was ambiguity as such in s 71 of the Act. Putting that to one side, it may be accepted that the purpose of the Act is beneficial or remedial. However, in the context of legislation creating and funding rights to compensation which might continue for many years, with compulsory insurance, a purpose of rehabilitation and monitoring by a Committee,[14] it does not follow that a worker is entitled to compensation from their present employer for the totality of their permanent impairment arising from multiple injuries sustained at different times (and for which compensation has been paid).
To adapt the High Court’s observations in relation to statutory compensation for victims of crime, the Act confers benefits, and no doubt it should not be construed restrictively, but in dealing with specific limited words like those in ss 70 and 71, it is difficult to state the legislative purpose except at such extreme levels of generality that it is not useful in construing particular parts of the legislative language.[15]
That lack of utility is compounded when the express objects of the Act, set out in s 2, include the competing objects of ensuring that the scheme for the rehabilitation and compensation of injured workers: is fair, affordable, efficient and effective; provides adequate and just compensation to injured workers; and is balanced to ensure that the costs of workers compensation are contained to reasonable levels for employers.
For these reasons, we do not accept the appellant’s submission that there is a discernible legislative intention that workers who suffer a whole person impairment of 15% or more as a result of compensable injuries sustained at different times are to be understood as suffering a serious impairment and compensated at the rate directly commensurate with their actual level of impairment rather than ‘the discount rates’ in s 71(3). The appellant also argued that the respondent’s construction of s 71 would have adverse implications for the appellant under s 65 of the Act, which limits the period over which benefits for incapacity may be paid for workers who have permanent impairment of less than 15%. This limitation applies to a worker who suffers a ‘relevant permanent impairment’ of less than 15%. No argument was put as to what is captured by that phrase. In any event, for the same reasons as just stated, we do not accept the submission that adverse implications under s 65 demonstrate a legislative intention that workers who suffer a whole person impairment of 15% or more as a result of compensable injuries sustained at different times should be compensated without that limitation.
While it may appear to the appellant in this case to be harsh or capricious or unfair that the effect of s 71 is that she is compensated for her 22% permanent impairment by two payments of compensation calculated pursuant to s 71(3), and thereby receives less compensation than if they were dealt with together pursuant to s 71(1), that may be the consequence of the legislature’s intention, as discerned from s 53 and the other provisions that refer to compensation ‘in respect of an injury’, that compensation is payable to a worker under the Act on an ‘injury by injury’ or ‘claim by claim’ basis, rather than on a whole person approach where the current permanent impairment has arisen from multiple injuries occurring at different times.
The employer’s obligation to pay and ‘double dipping’
On the appellant’s construction of s 71, the employer would be liable for compensation for the worker’s degree of permanent impairment where that was caused or materially contributed to by a previous injury or injuries, including those which were caused by or arose out of previous employment. Further, the worker would be entitled to compensation for the worker’s degree of permanent impairment at the time of the assessment, even if the degree of permanent impairment was referable in part to a previous injury or injuries for which the worker had received compensation under s 71 in the past.
The appellant argued that the amount of any previous compensation the worker had received would be set off against their entitlement to compensation under s 71. There is no statutory mechanism which makes provision for this set off. Consequently, reliance was placed on the decision of the Northern Territory Court of Appeal in Northern Territory v Pengilly (2004) NTLR 18 (‘Pengilly’). In that case, the worker had been assessed in 1997 as having a permanent impairment of 43% of the whole person following an injury to her arm which required surgery and subsequently caused the contraction of dermatitis. The 43% was comprised of 24% attributable to the dermatitis and 25% attributable to the arm injury which, according to the combined values chart in the Guidelines, gave rise to 43% WPI. Pursuant to s 71 of the Act, she was paid 43% of 208 times her average weekly earnings. In 2001, the worker’s dermatitis deteriorated but her arm injury resolved. She was assessed as having a permanent impairment of 60% attributable to the dermatitis. She reopened her claim for compensation. The Work Health Court concluded that the worker was entitled to 17% of 208 times her average weekly earnings, being 60% less 43%. On appeal, the Supreme Court held that the worker was entitled to 60% of 208 times her average weekly earnings less the actual amount of compensation that had previously been paid to her.
The Court held (at [10]) that, pursuant to s 71, the worker is entitled to compensation for a 60% permanent impairment assessed in today’s terms (referring to the phrase ‘at the time the payment is made’). It had been argued that the worker’s claim was a new claim for a 60% permanent impairment that exists today, not a claim under s 71 for an additional percentage for the increased incapacity over and above the 43% incapacity that existed in 1997. The Court held that the employer’s concession that the worker, in 2001, could sue for compensation on the basis of 60% impairment (a matter about which the Court stated it expressed no opinion (see [9])) carried with it the concession that the appellant did not finally discharge its liability in respect of 43% of the worker’s current permanent impairment by its payment in 1997. The Court held (at [11]) that the worker was entitled to compensation based upon the 60% permanent impairment and, because it arose out of the same injury which resulted in a 43% impairment in 1997 and for which the employer compensated the worker, the employer was entitled to set off the amount paid in 1997 in pro tanto discharge of its later liability.
That case is of little assistance here. First, the employer had conceded that the worker could make a new claim for the 60% permanent impairment. There is no such concession here; that is the very substance of the debate. Second, that case concerned a second claim in respect of permanent impairment arising out of the same injury. That is not the situation here. Further, that fact had the consequence that the employer was the same, so a pro tanto set off of the amount of compensation the employer had previously paid was available under the general law.
While that situation pertains here as well, the appellant’s construction of s 71 would equally operate where the worker’s permanent impairment is a consequence of one or more prior injuries which arose out of or in the course of employment with one or more different employers than the present employer. In that situation, the legal basis upon which the current employer would be entitled to deduct from the compensation it pays to the worker the amount/s previously paid to the worker by other employer/s, is not clear and was not explained.
Further, where (as is the case here) the worker’s previous degree of permanent impairment was below 15% of the whole person, and the worker’s current degree of permanent impairment is above 15% of the whole person, but the component attributable to the injury sustained in the course of the current employment was also below 15%, significant difficulties arise as to upon which employer the burden of the increased compensation should fall, and how that burden is to be distributed between them.
By way of example, assume a worker suffers an injury in Year X and is assessed as having a permanent impairment of 9% of the whole person. By s 71(3) of the Act, the worker was entitled to payment of 2% of 208 times their average weekly earnings in Year X. The worker was paid that amount by their employer. In Year Y, the worker suffers another injury whilst working for a different employer. The worker is assessed as having a total permanent impairment of 22%, which is comprised of 9% attributable to the first injury and 13% attributable to the second injury. On the appellant’s construction, by s 71(1), the worker would now be entitled to payment of 22% of 208 times their average weekly earnings, which is payable by the second employer, despite the fact that only 13% of the worker’s current permanent impairment is attributable to an injury in the current employment which would, on its own, entitle the worker to only 8% of 208 times their average weekly earnings.
Numerous questions arise. First, is the current employer obliged to pay the whole of the 22% of 208 times the worker’s average weekly earnings?
If not, by what mechanism would the current employer deduct the 2% already paid? Unlike the situation in Pengilly, there is no entitlement under the general law to set off the past payment from its obligation to pay compensation because the past payment was paid by a different employer.
If so: (a) the worker would receive the current compensation in addition to the 2% of 208 times their average weekly earnings paid in Year X, thereby receiving more compensation than they are entitled to; and (b) the current employer would be obliged to pay compensation for a component of the permanent impairment that had nothing to do with their workplace and was attributable to a past employment.
The Act does not contain any statutory mechanisms or provision for resolving these questions.
While s 126A of the Act deals with the respective liability of employers (and their insurers) to pay compensation where there is more than one injury,[16] it could only operate, in its terms, in respect of the compensation liability of each employer for each injury dealt with separately under s 71(3), and would not address the additional liability to pay compensation which arises because of the operation of s 71(1).
The absence of any provision which deals with the apportionment of this liability is a contextual indication that s 71 was not intended to operate so as to give rise to such issues. This also points against the appellant’s construction.
The Guidelines intended as nationally consistent guides
Some legislative history

Prior to 1991, s 70 of the Act defined ‘permanent impairment’ by reference to an impairment or impairments assessed in accordance with the prescribed guides, and r 9(1) of the Return to Work Regulations 1986 (NT) prescribed those guides to be the American Medical Association Guides to the Evaluation of Permanent Impairment (4^th edition) (‘AMA Guides’).
The Act was amended in 1991 to:[17]
(a)amend the definition of ‘permanent impairment’ in s 70 to reduce the percentage of whole person impairment from 15% to 5%;
(b)increase the compensation payable in s 71(2) and 71(3) from 104 times average weekly earnings to 208 times average weekly earnings; and
(c)insert s 71(3), providing for the compensation payable to persons with a whole person impairment of less than 15% in accordance with the Table.
When the Bill for that amendment Act was introduced into the legislature, the Minister moving the Bill said that it was the result of the Work Health Benefits Review announced in September 1990.[18] One of the issues in that Review was about the use of the AMA Guides for calculations of s 71 benefits. It was noted that the AMA Guides were used under the Act.[19] Consideration had been given in the Review to adopting the Table of Maims rather than the AMA Guides, the main difference being that the AMA Guides use the whole of body approach to the measurement of loss of function of the injured worker compared to a normal healthy person.[20] The Review concluded that the AMA Guides had a number of advantages over the Table of Maims, including that percentage impairments for multiple injuries are combined in such a way that the overall impairment can never be assessed at more than 100% of the whole body, and it was being used increasingly for a variety of purposes by workers’ compensation schemes, motor accident compensation schemes and various Commonwealth departments.[21] The Review recommended that the AMA Guides be retained, that recommendation was adopted, and no legislative change was made.[22]
The Second Reading Speech concluded with the following:[23]
I am sure there will remain some people in the community who are unhappy with the amendments proposed by the government. However, we must remember that the intention of the [RTWA] is not to provide huge gains to injured workers. The first responsibility of the work health system is to stop accidents at work. The second responsibility is to get employees back to work if they are injured. The third responsibility is to provide monetary compensation to those injured persons so that they can pay their medical costs and continue to support themselves and their families. All of the above must happen at a cost the community can afford. I believe the amendments in this bill achieve a fair mix of compensation and affordability...
Section 70 was amended in 2015 to remove the reference to ‘prescribed guides’ and refer instead to ‘guides approved and published by the Authority’.[24] At the same time, r 9 of the Regulations was repealed.[25]
The Explanatory Statement to the Amendment Act stated that s 70 was amended to empower the Authority to approve guides for the evaluation of permanent impairment instead of the guides being prescribed by regulation. This was to enable greater flexibility in the future adoption of proposed nationally consistent guides currently being developed in consultation with the jurisdictions through Safe Work Australia.[26]
These, and a number of other amendments, were passed following a further extensive review of the Act.[27] The Minister for Employment and Training introduced the amendment Bill by saying that the review had advocated changes to benefits necessary if the workers’ compensation scheme is to remain affordable for Northern Territory businesses.[28] One significant change was to restrict compensation to five years for less seriously injured workers, while others would increase benefits and provide increased transparency and claims management. The Bill was said to be the first stage of the government’s commitment ‘to provide a more efficient and effective sustainable’ workers’ compensation scheme.[29]
The Guidelines adopted in the Northern Territory
As set out above, cll 1.63, 1.27, 1.28 and 11.10 of the Guidelines provide that the degree of permanent impairment resulting from pre-existing impairments should not be included in the final calculation of permanent impairment if they are not related to the compensable injury and that the degree of impairment due to any previous injury, known as ‘the deductible proportion’, is to be deducted from the degree of permanent impairment determined by the assessor.
The Guidelines state (in the Foreword and the Introduction) that they are based on a template guide developed through a national process facilitated by Safe Work Australia. They were initially developed for use in the New South Wales workers’ compensation system and incorporate numerous improvements identified across their use in New South Wales and South Australia. The methodology in the Guidelines is largely based on the American Medical Association’s Guides to the Evaluation of Permanent Impairment, 5^th Edition, which are the most authoritative and widely used source for evaluating permanent impairment around the world. The Guidelines have been adopted for use in multiple Australian jurisdictions.
The American Medical Association Guides to the Evaluation of Permanent Impairment, 5^th Edition contain section 1.6, headed ‘Causation, Apportionment Analysis, and Aggravation’. That section contains sub-section 1.6b, headed ‘Aportionment Analysis’. That sub-section states that apportionment analysis represents a distribution or allocation of causation among multiple factors that caused or significantly contributed to the injury or disease and resulting impairment. The factor could be a pre-existing injury, illness or impairment. In some instances, the physician may be asked to apportion or distribute a permanent impairment rating between the impact of the current injury and the prior impairment rating. Generally, the most recent permanent impairment rating is calculated, and then the prior impairment rating is calculated and deducted. The remaining impairment rating would be attributed or apportioned to the current injury or condition.
The Guidelines also state (in Appendix 2) the variations made to the national template guide. None of those variations relate to cll 1.6.3, 1.27, 1.28 or 11.10.
Effect of these matters on the constructional choice
It is abundantly clear from the explanatory materials referred to above that the intention of the legislature, at the time it considered and passed amendments to the Act, the last of which permitted the adoption of the nationally consistent guides, was that the nationally consistent guides would be adopted and applied in the Northern Territory worker’s compensation scheme, and could be so adopted and applied because they were consistent with the provisions of the Act.
Despite that, the appellant argued that the Guidelines must be construed differently in the Northern Territory as a consequence of the appellant’s construction of s 71 of the Act. In support of this argument, the appellant pointed to the express provisions in the South Australian and New South Wales workers’ compensation legislation prescribing that, in assessing a worker’s permanent impairment, any portion of the impairment attributable to a previous injury (whether a compensable injury pursuant to the scheme or not) is to be deducted from the assessed permanent impairment.[30] This was said to found the construction and operation of the nationally consistent guides adopted in those jurisdictions, and the absence of such express provisions in the Act was said to found the inconsistency between the Act (on the appellant’s construction of s 71) and the Guidelines adopted in this jurisdiction which compelled the ‘reading down’ of the Guidelines so as to render them consistent with the appellant’s construction of s 71.
The constructional choice that gives effect to the clear legislative intention that the nationally consistent guides for the assessment of permanent impairment would operate in the Northern Territory in essentially the same fashion as they do in other jurisdictions is to be preferred to the constructional choice which necessitates a reading down or severance of parts of the nationally consistent guides which the legislature intended to apply and operate in the Northern Territory.
While the general rule is that delegated legislation should not be referred to for the purpose of interpreting the Act under which they are made, there are recognised exceptions to that general rule, namely where:[31]
(a)the regulations together with the principal Act form part of a legislative scheme and it may be useful to refer to them to ascertain the nature of the scheme; and
(b)the Act and the regulations have been drafted and promulgated together to establish an interdependent regime.
Both of those exceptions are applicable here to some degree. The Guidelines and the Act together form a legislative scheme for the assessment and compensation of permanent impairment caused by or materially contributed to by workplace injury. The Act expressly contemplates that the assessment will occur pursuant to and in accordance with the Guidelines. Further, at the time of the 2015 amendment to s 70 of the Act, the nationally consistent guides were in contemplation and being drafted for the purpose of establishing that interdependent regime.
Conclusions
The constructional choice posed by the language of s 71 of the Act is to be resolved in favour of the respondent’s construction, rather than the appellant’s.
The reasons for that choice are essentially: (a) the centrality of an ‘injury’ to the employer’s liability to pay compensation under the Act, which indicates that compensation is payable in respect of an injury and points against a ‘whole of person’ approach to the concept of permanent impairment in s 71; (b) the absence of any provisions in the Act dealing with the issues as to the worker ‘double-dipping’ and respective liabilities of employers (and insurers) for the additional compensation payable where a subsequent injury takes the worker over the 15% threshold; and (c) the effect of the appellant’s construction on the validity and/or construction and operation of the Guidelines.
Consequently, the appellant’s arguments about how the Guidelines should be construed in reading them down to be consistent with s 71 of the Act fall away.
To be clear, we consider that the requirements in the Guidelines to deduct the proportion of the WPI which is attributable to a previous injury or pre-existing condition should be construed according to their plain and natural meaning (so as to require deductions for both previous compensable and non-compensable injuries or conditions).[32] We do not accept that the Guidelines should be construed so as to only require deduction of proportions of the WPI attributable to non-compensable injuries or conditions.
It follows that there was no error in the construction or application of the Guidelines by the Supreme Court or the Work Health Court.
Disposition
The appeal is dismissed.
We will hear the parties as to costs.

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[1] Woods v Northern Territory of Australia [2024] NTSC 35 (‘Reasons’).

[2]Reasons at [2]-[11].

[3]Woods v Northern Territory of Australia [2023] NTWHC 08.

[4]Two other grounds were abandoned before the hearing of the appeal.

[5]So much is confirmed by ss 54(3), 55 (in relation to the contraction of a disease), 57, 58 (in relation to a heart attack injury or a stroke injury), 60 and 61A(1).

[6]See, for example, SAS Trustee Corporation v Miles (2018) 265 CLR 137 at [1], [17], [20] per Kiefel CJ, Bell and Nettle JJ, [41] per Gageler J.

[7]Ibid at [20] per Kiefel CJ, Bell and Nettle JJ, citing, inter alia, SZTAL v Minister for Immigration and Border Protection (2017) 262 CLR 362 at [38] per Gageler J.

[8]Section 24(2)(a), Interpretation Act 1978 (NT).

[9]See D Pearce, Statutory Interpretation in Australia, 9^th ed, [2.59].

[10]Public Transport Commission of NSW v J Murray-More (NSW) Pty Ltd (1975) 132 CLR 336 at 350 per Gibbs J.

[11]Federal Commissioner of Taxation v Smorgon (1977) 16 ALR 721 at 729 per Stephen J.

[12]Victoria v The Queen [2014] FSCA 311 at [61] per the Court.

[13]Esso Australia Resources Lt d v Commissioner of Taxation (1998) 83 FCR 511 at 518-519 per Black CJ and Sundberg J, at 670 per Finkelstein J.

[14]See Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at [27] per Gleeson CJ, Gummow, Hayne and Crennan JJ. As to the legislative objects of a financially sustainable workers’ compensation scheme, see s2(c)(iii) of the Act and the explanatory materials referred to below.

[15]Victims Compensation Fund Corporation v Brown (2003) 77 ALJR 1797 at [33] per Heydon J (McHugh ACJ, Gummow, Kirby and Hayne JJ agreeing).

[16]See Allianz Australia Insurance Ltd v Territory Insurance Office (2008) 23 NTLR 186.

[17]These amendments were effected by ss 10 and 11 of the Work Health Amendment Act (No 2) 1991 (NT) (No 59 of 1991), which came into effect on 15 October 1991.

[18]Legislative Assembly, Work Health Amendment Bill, Second Reading Speech, 9 May 1991, p 1199.

[19]Ibid, p 1202 ff.

[20]Ibid, p 1203.

[21]Ibid.

[22]Ibid.

[23]Ibid, p 1207

[24]These amendments were effected by s 17 of the Workers Rehabilitation and Compensation Legislation Amendment Act 2015 (NT) (No 9 of 2015), which came into effect on 1 July 2015.

[25]Workers Rehabilitation and Compensation Legislation Amendment Act 2015 (NT), s 29.

[26]Explanatory Statement to the the Workers Rehabilitation and Compensation Legislation Amendment Bill 2015, cl 17.

[27]Legislative Assembly, Workers Rehabilitation and Compensation Legislation Amendment Bill, Second Reading Speech, 26 February 2015, p 6057.

[28]Ibid.

[29]Ibid, p 6059.

[30]See s 22(1) and (8)(g) of the Return to Work Act 2014 (SA) and s 323(1) of the Workplace Injury Management and Workers Compensation Act 1998 (NSW).

[31]D Pearce, Statutory Interpretation in Australia, 9^th ed, [3.49] and the authorities there referred to.

[32]Noting that the Guidelines contain a definition of the term ‘injury’ which is in the same terms as the definition of ‘injury’ found in the Act: see Appendix 1.