Slade v Insurance Australia Ltd t/as NRMA

Supreme Court of NSW|2020-06-10|Before: Wright J

m 1 October 2008) Motor Accident Permanent Impairment Guidelines (effective from 1 Jun 2018) Category: Principal judgment Parties: Elizabeth Anne Slade (Plaintiff) Insurance Australia Limited trading as NRMA Insurance (First Defendant) State Insurance Regulatory Authority (Second Defendant) Sophie Jones in her capacity as the Proper Officer of the State Insurance Regulatory Authority (Third Defendant) Dr Alan Jager in his capacity as a Medical Assessor for the State Insurance Regulatory Authority (Fourth Defendant) Representation: Counsel: M Robinson SC with J Malouf (Plaintiff) K Rewell SC (First Defendant)

Solicitors: North Coast Compensation Lawyers (Plaintiff) Hall & Wilcox (First Defendant) File Number(s): 2019/359995

Judgment

By an amended summons filed on 11 May 2020, the plaintiff, Ms Slade, has sought judicial review of decisions of: (a) the third defendant who is relevantly the proper officer of the second defendant, the State Insurance Regulatory Authority (SIRA); and, (b) the fourth defendant, Dr Jager, who is a medical assessor appointed by SIRA for the purposes of the Motor Accidents Compensation Act 1999 (NSW) (the MAC Act).
The decisions of which Ms Slade seeks judicial review relate to her claim for damages arising out of the motor vehicle accident that occurred on 28 April 2015, near Gloucester in New South Wales. The first defendant, Insurance Australia Ltd trading as NRMA, was the insurer in respect of the other vehicle involved in the accident and has admitted liability.
All of the defendants other than NRMA have filed submitting appearances and, as a result, NRMA is the only active defendant.

Background

On 28 April 2015, Ms Slade was the driver of a car that hit another vehicle that was stationary on the road and her car flipped over and landed back on its wheels facing in the wrong direction. This accident is referred to as the 2015 motor accident. She had six months off work with physical injuries and pain. She experienced no psychological stress, however, until mid-February 2016 when she had a "near miss" when driving and experienced a panic attack. This subsequent event is referred to as the 2016 near miss.
After the 2016 near miss, Ms Slade escalated her alcohol consumption dramatically to a litre of vodka a day and developed nightmares and insomnia and experienced flashbacks to the first accident. She has received intensive treatment from a psychologist and a psychiatrist and she continues to take high-dose antidepressant medication, high dose alpha blocking medication and sedative and atypical antipsychotic medication.
Despite that intensive treatment and a reduction in her alcohol consumption, Ms Slade continues to feel anxious most of the time with reduced enjoyment and sleep, flashbacks, nightmares, avoidance behaviour, reduced energy, appetite, libido and concentration, and passive suicidal thoughts.
Liability having been admitted by NRMA, as the insurer of the insured vehicle, disputes arose between Ms Slade and NRMA concerning the following matters: 1. whether Ms Slade's degree of permanent impairment as a result of the injury caused by the 2015 motor accident was greater than 10%; 2. whether her treatment was related to the injury caused by the 2015 motor accident; and 3. whether any such treatment was reasonable and necessary in the circumstances.
On 26 September 2018, an application for the assessment of these matters was lodged on behalf of Ms Slade and the matters were referred to the Medical Assessment Service (MAS).
On 9 April 2019, Ms Slade was assessed by a medical assessor, Dr Jager, the fourth defendant.
On 24 April 2019, Dr Jager gave three certificates in relation to the assessment of the matters referred to him to the following effect: 1. in MAS matter number 2018/02/3778, that the injury, being Chronic Post-traumatic Stress Disorder (PTSD), caused by the 2015 motor accident gave rise to a permanent impairment which was not greater than 10%; 2. in MAS matter number 2018/01/3773, that certain treatments listed in the certificate related to the injuries caused by the 2015 motor accident and that the other treatments did not; and 3. in MAS matter number 2018/01/3773, that certain treatments listed in the certificate were reasonable and necessary in the circumstances and that the other treatments were not.
In accordance with s 61(9) of the MAC Act, the medical assessor gave reasons for his findings and these reasons were expressly incorporated in the certificates.
On 1 July 2019, Ms Slade applied, under s 63 of the MAC Act, to the proper officer of SIRA to refer the medical assessments by the medical assessor to a review panel of medical assessors for review on the basis that the assessments were incorrect in material respects.
On 16 August 2019, the proper officer determined that she was not satisfied that there was reasonable cause to suspect that the medical assessments were incorrect in any material respect and accordingly the review application was dismissed.

Ms Slade's judicial review application

On 15 November 2019, Ms Slade filed a summons invoking the supervisory jurisdiction of this Court, confirmed by s 69 of the Supreme Court Act 1970 (NSW), seeking, among other things: 1. an order setting aside "the Certificate (MAS matter number 2018/01/3773) and Statement of Reasons issued by [SIRA] and constituted by [the medical assessor] on 24 April 2019"; and 2. an order "setting aside the Statement of Reasons issued by [SIRA] and constituted by the [proper officer] on 16 August 2019"; and 3. an order remitting the matter to SIRA for determination according to law.
On 11 May 2020, the plaintiff filed an amended summons in which, in addition to the orders sought in the original summons, she also sought orders which included an order "setting aside the Certificate (MAS matter number 2018/02/3778) and the Statement of Reasons issued by [SIRA] and made by the [medical assessor] on 24 April 2019".
As a result, it appeared, and the parties accepted for the purposes of these proceedings, that the medical assessor's assessments covered by the three certificates issued on 24 April 2019 were all challenged in these proceedings.
In respect of the medical assessor's certificates and statement of reasons of 24 April 2019, the errors of law on the face of the record were contended to be, in substance: 1. that the certificates were "incorrect in a material respect" in that the medical assessor did not correctly apply the legal principles in relation to causation; and 2. the medical assessor "failed to provide sufficient reasons" for his decisions.
In relation to the proper officer's determination refusing the review application and statement of reasons of 16 August 2019, the grounds relied upon by the plaintiff were: 1. jurisdictional error; and/or 2. errors of law on the face of the record; and alternatively, 3. failure to exercise her statutory power in making the decision.
The proper officer's jurisdictional error or error of law on the face of the record was said to be constituted by her failure to apply the correct legal test.
If it is determined that the medical assessor's certificates should be set aside, it will be unnecessary to address whether the proper officer's determination was affected by any relevant error or failure to exercise statutory power. Accordingly, I shall consider the challenge to the medical assessor's certificates first and then only consider the challenge to the proper officer's determination should that be required.
Before doing so, however, it is necessary to address a preliminary issue.

Extension of time

Under r 59.10(1) of the Uniform Civil Procedure Rules 2005 (NSW) (UCPR), proceedings for judicial review of a decision must be commenced within three months of the date of the decision. In the present case, the proceedings were not commenced within three months of the medical assessor's decisions set out in the three certificates given on 24 April 2019. The plaintiff sought, informally, an extension of time in that regard and the first defendant consented to an extension of time being granted, on the basis that it was appropriate for Ms Slade to exhaust her opportunity to seek a review of the medical assessor's decision, before commencing proceedings in this Court. In my view and in accordance with the approach outlined by Beazley JA (McColl and Macfarlan JJA agreeing) in Rodger v De Gelder (2011) 80 NSWLR 594; [2011] NSWCA 97 at [91] - [92], this is an appropriate course for Ms Slade to have taken. In these circumstances, I shall grant the plaintiff an extension of time in which to commence the present proceedings to 15 November 2019.

The medical assessor's certificates and reasons

As noted above, the medical assessor dealt with three matters: (a) whether the injuries caused by the 2015 motor accident gave rise to a permanent impairment which was not greater than 10%; (b) whether the treatments in question related to injuries caused by the 2015 motor accident; and, (c) whether the treatments in question were reasonable and necessary in the circumstances.
Formally, a certificate was given in respect of each of those matters but there was only one set of reasons accompanying the certificates. In each case, these reasons were expressly stated to form part of the certificate.
In his reasons for decision, the assessor identified the three matters, or medical disputes, that had been referred to him and noted the material which he had seen and considered. The injuries to be assessed were described as: "Psychological - Posttraumatic Stress Disorder and/or Depression".
In addition, the assessor listed at some length the treatments which were the subject of dispute.
The assessor recorded in his reasons the history given by Ms Slade which relevantly included that: 1. she was on no psychiatric medication at the time of the 2015 motor accident and she had no family history of psychiatric illness; 2. prior to the 2015 motor accident, she always felt "ten foot tall and bullet-proof" and was a very outgoing person who enjoyed playing rhythm guitar, drums and vocals in a rock band; 3. in the 2015 motor accident: "Ms Slade was the driver and sole occupant of a car travelling at 80 km per hour. It hit a stationary vehicle on the road when she was unable to steer past it. Her car flipped onto its roof, rebounded to the opposite side of the road and bounced back to the right way up facing in the opposite direction. Her head hit and smashed the driver's door window. The car came to rest and then the airbags deployed. It was difficult for her to undo her seatbelt and she had to force the driver's door open, put the hazard lights on and self-extricate from the vehicle." 1. her treatment after the 2015 motor accident included physiotherapy, anti-inflammatory and analgesic medication but she was not treated by a psychiatrist or psychologist nor did she have any psychiatric medication; 2. Ms Slade said that after the 2015 motor accident she had no psychiatric problems and that her life was going fine and "basically back to normal" except for pain; and 3. immediately after the 2016 near miss, which occurred when she was driving to work, Ms Slade: "experienced a panic attack. She hyperventilated, was tremulous and vomited. The attack lasted ten minutes before she re-entered her car. Upon arrival at work she vomited again. She had no treatment but her symptoms increased over the ensuing three months. Her vodka intake increased from one glass per day to one litre per day. She developed frequent nightmares and insomnia. She ceased work because 'I'd imploded. I was afraid it would impact on my functioning at work'. Her GP diagnosed PTSD and she was put off work and has never returned. She was prescribed Prazosin (alpha blocker) 1 mg at night and sertraline (antidepressant) 100 mg in the morning. She was referred to psychiatrist, Dr Richardson, whom she attends every 2 to 3 months."
As to her current and proposed treatment, the assessor recorded: "She sees Dr Richardson, psychiatrist, every 2 to 3 months and takes Mirtazapine (antidepressant) 90 mg at night, Desvenlafaxine (antidepressant) 100 mg in the morning, Quetiapine (atypical antipsychotic) 25 mg twice a day and 350 mg at night, Diazepam (sedative) 5 mg at night and Prazosin (alpha blocker) 10 mg at night. In addition, she takes Panadol Osteo and Nurofen. She also sees a psychologist every four to six weeks. There have been no psychiatric hospitalisations."
In addition to finding that there were no inconsistencies in her presentation, the assessor also noted that she was unfit for all employment.
Next the assessor reviewed the relevant documentation and, in particular, noted, inter alia: "The Claimant's Submissions on Causation argues that the fact that the condition was triggered by a subsequent event does not mean that the subject accident was not causative in the legal sense… nor does it matter that the motor accident was not the sole cause. … The report of Dr BD Parsonage, psychiatrist, dated 11/7/17 notes the claimant was treated with Sertraline 50 mg daily for depressive symptoms from 2008. He did not specifically state the dose she was taking at the time of the accident of 28/4/15. He diagnosed PTSD and Major Depressive Disorder, stating that the 2015 accident 'primed her' to develop PTSD and both the April 2015 and February 2016 incidents were the cause of her PTSD." (emphasis in original)
The evidence before the Court established that the documentation provided in support of Ms Slade's application to the MAS included an occupational therapy report by Ms Erika Stevenson dated 10 June 2017 which set out in some detail: Ms Stevenson's assessment of Ms Slade; the past gratuitous assistance she had received; her present and future domestic care assistance and transportation assistance requirements; and, other matters in relation to future occupational therapy, physiotherapy, and related needs. Although this assistance is referred to in a number of items on the List of Treatment Disputes to be Assessed (on pp 10 and 11 of the assessor's reasons), the assessor did not refer to, or review, Ms Stevenson's report in the section of his reasons under the heading "Review of Documentation" or elsewhere.
Furthermore, even though the assessor summarised some of Dr Parsonage's conclusions in his report of 11 July 2017, as set out in the passage quoted above, the assessor did not refer to, or comment on, the last paragraph of Dr Parsonage's report which stated: "In my opinion the majority of the domestic assistance required by Mrs Slade as outlined by Ms Stephenson [sic] is as a result of her psychological condition. This is because her psychological condition is associated with marked impairment of concentration, persistence and pace and reduced motivation."
Under the headings "Conclusions", the assessor stated: "Diagnosis and Causation … She fulfils diagnostic criteria for Chronic Posttraumatic Stress Disorder (PTSD). If not for the February 2016 incident, she would not have PTSD. If not for the April 2015 incident, she would not have PTSD. I attributed causation equally between the two incidents. Summary of Injuries Listed by the Parties and Caused by the Accident The following injuries WERE caused by the motor accident: • Chronic PTSD". (emphasis in original)
The assessor also determined that Ms Slade's impairment was now permanent.
The assessor then set out his assessment of permanent impairment as 19% Whole Person Impairment (WPI). This assessment was described as being "made in accordance with the American Medical Associations Guides to the Evaluation of Permanent Impairment (Fourth Edition) and the Motor Accident Permanent Impairment Guidelines 1 June 2018". It is implicit that this assessment of the WPI was the degree of impairment at the time of the assessment.
Under the heading "Apportionment", the assessor indicated that he had calculated the impairment that existed before the 2016 near miss as 0% WPI. In a number of places, this is described as "Subsequent impairment" or "Subsequent % whole person impairment". These descriptions, however, appear to be erroneous. The finding of 0% WPI related to the degree of previous impairment, that is, psychiatric impairment prior to the 2016 near miss. It should not have been described as an assessment of "subsequent impairment".
Under that same heading "Apportionment", the assessor said: "I have calculated the impairment that existed before the [2016 near miss] in the table below. She derives no discernible lasting benefit from the treatment despite the treatment being entirely appropriate and reasonable. As stated clearly above, the PTSD would not exist without both accidents having occurred. I am required however rather than dividing the current impairment equally between the two accidents to calculate the impairment that was present prior to the [2016 near miss] and separately calculate the impairment currently present. … [Here, the assessor included a table explaining how he calculated the impairment that existed before the 2016 near miss as 0% although this is erroneously described in the table as "Subsequent % whole person impairment".] Summary of permanent impairment A Current % permanent impairment 19% B Subsequent % permanent impairment 19% C Adjustments % for effects of treatment 0% Final % permanent impairment 0%" (emphasis in original)
On that basis, the assessor certified that the injury, being PTSD, caused by the 2015 motor accident gave rise to a permanent impairment which was not greater than 10%. It can be noted that the assessor did not explain why he apparently subtracted the 19% "Subsequent % permanent impairment" from the 19% "Current % permanent impairment" to arrive at his "Final % permanent impairment" of 0%. Nor did he provide any other relevant reasoning to explain his conclusion that the degree of permanent impairment as a result of the injury caused by the 2015 motor accident was less than 10%, namely 0%.
The assessor then turned to consider the question whether the treatments claimed by Ms Slade related to the injuries caused by the 2015 motor accident. Under the heading "Treatment - Causation", the assessor stated: "As clearly stated above, without the [2015 motor accident] there would be no PTSD and no requirement for treatment. The PTSD requires treatment using the various modalities currently received by the claimant. [Specified treatments] are all causally related to the injuries caused by the accident as they represent mainstream treatment of PTSD. Gratuitous personal and domestic assistance and Paracetamol are not causally related to the psychiatric injury as they are not mainstream treatments of PTSD." (emphasis in original)
Finally, under the heading "Treatment - Reasonable and Necessary", the assessor concluded that certain of the treatments claimed by Ms Slade were reasonable and necessary and found that other treatment was not and said, inter alia: "Gratuitous personal and domestic assistance is not causally related and therefore not reasonable and necessary. … 0-8 tablets of 500 mg Paracetamol is not causally related and therefore not reasonable and necessary."
In neither the "Treatment - Causation" section nor the "Treatment - Reasonable and Necessary" section of his reasons did the assessor specifically consider or refer to Ms Stevenson's report which dealt in detail with gratuitous personal and domestic assistance and other related matters. Nor did he refer to the last paragraph of Dr Parsonage's report, which has been quoted above. The assessor did not explain why their opinions in these regards should not be accepted.
On the bases set out in his reasons, the assessor gave certificates to the effect that: 1. Ms Slade's PTSD, caused by the 2015 motor accident, gave rise to a permanent impairment which was not greater than 10%; 2. certain treatments listed in the second certificate related to the injuries caused by the 2015 motor accident and other treatments did not; and 3. certain treatments listed in the third certificate were reasonable and necessary in the circumstances and other treatments were not.

The medical assessor's certificates - Grounds of review

The plaintiff's two grounds of review in relation to the medical assessor's three certificates were, in substance that: 1. the assessor erred in law when determining the degree of permanent impairment as a result of the injury caused by the 2015 motor accident and whether the treatments claimed related to the injury caused by the motor accident because he did not apply the correct principles in relation to causation; and 2. the assessor failed to give adequate reasons for his decisions.

The medical assessor's certificates - Submissions

In substance, Mr Robinson of Senior Counsel, who appeared with Mr Malouf for Ms Slade, submitted that the medical assessor made errors of law on the face of the record in relation to each of the matters concerning which the assessor gave a certificate.
Reflecting the first ground of review, the plaintiff submitted that the assessor made errors of law as to the requirements of the relevant provisions of the Motor Accident Permanent Impairment Guidelines (1 June 2018) (the 2018 Guidelines) including, in particular, par 1.34 and as to the legal principles to be applied in determining causation.
As to the second ground of review, the plaintiff's submissions were to the effect that the assessor failed to give adequate reasons for his decisions in relation to: 1. the degree of Ms Slade's whole person impairment "as a result of the injuries caused by the [2015] motor accident"; 2. whether the treatments claimed by Ms Slade "relate[d] to the injury caused by the [2015] motor accident"; and 3. whether any such treatments claimed by Ms Slade were "reasonable and necessary in the circumstances".
The principal area in which the assessor failed to give reasons was said to be in relation to the causal connection between the impairment and the injury suffered in the 2015 motor accident.
Mr Rewell of Senior Counsel, who appeared for NRMA, submitted in effect that there were no errors of law on the face of the record. In particular, it was contended in relation to the assessor's assessment of impairment caused by the 2015 motor accident that there was a fundamental distinction between the injury caused by an accident and any impairment resulting from injury caused by the accident. Thus, it was said that, while an injury, PTSD, may have been caused by the 2015 motor accident, there was no impairment resulting from this injury before the 2016 near miss. In these circumstances, the assessor made no error in his application of par 1.34 of the Guidelines when he concluded that the degree of permanent impairment as a result of the injury caused by the 2015 motor accident was 0%.
Similarly, in relation to the treatment disputes, it was contended that the need for treatment or attendant care and domestic assistance was the consequence of impairment resulting from an injury. In the present case, because no impairment resulted from the 2015 motor accident, it was said that no need for certain treatment or attendant care or domestic assistance could have been caused by that accident. Accordingly, it was submitted that there was no error in the assessor's finding that this treatment or care and assistance was not related to the psychiatric injury, PTSD, caused by the 2015 motor accident because that accident did not give rise to any impairment.
Further, it was contended in substance that, since the need for the care and assistance was not caused by the 2015 motor accident, the assessor did not err in law by concluding that such care and assistance, and part of the psychiatric and psychological treatment and medication, were not reasonable and necessary.
In addition, it was submitted that, in the assessor's clinical judgement as a psychiatrist, he determined that Ms Slade's symptoms did not give rise to a need for the treatment or care and assistance that was rejected, and no error was disclosed.
As I understood his submissions, Mr Rewell also contended that, in the circumstances and particularly having regard to the distinction between impairment and injury, the assessor's reasoning was adequately set out in the reasons incorporated into the three certificates.

The medical assessor's certificates - Consideration

Relevant statutory provisions and paragraphs of the 2018 Guidelines

Part 3.4, ss 57 to 65, of the MAC Act provides for the medical assessment of injuries and impairment, as well as treatment in relation to those injuries and impairment, which arise from motor vehicle accidents which occurred prior to 1 December 2017.
Section 58(1) of the MAC Act identifies the types of matters that are to be the subject of medical assessment under Pt 3.4 and relevantly provides: "(1) This Part applies to a disagreement between a claimant and an insurer about any of the following matters (referred to in this Part as medical assessment matters): (a) whether the treatment provided or to be provided to the injured person was or is reasonable and necessary in the circumstances, (b) whether any such treatment relates to the injury caused by the motor accident, (c) (Repealed) (d) whether the degree of permanent impairment of the injured person as a result of the injury caused by the motor accident is greater than 10%. (e) (Repealed)"
In relation to matters concerning treatment referred to in s 58(1)(a) and (b), "treatment" is defined in s 42 of the MAC Act as follows: "treatment means: (a) medical treatment, or (b) dental treatment, or (c) the provision of rehabilitation services, or (d) the provision of attendant care services, or (e) the provision, replacement or repair of artificial members, eyes or teeth, crutches or other aids or spectacle glasses, whether or not at a hospital." and, in s 3, "attendant care services" is defined as meaning: "services that aim to provide assistance to people with everyday tasks, and includes (for example) personal assistance, nursing, home maintenance and domestic services."
It can be seen that the three matters referred to the assessor in the present case fell within s 58(1)(a), (b) and (d). These types of matters can be referred, under s 62, to a medical assessor for assessment.
Section 61 of the MAC Act deals with the certification and status of an assessor's assessment of matters referred to the assessor under s 62. The relevant provisions of s 61 include: "(1) The medical assessor or assessors to whom a medical dispute is referred is or are to give a certificate as to the matters referred for assessment. (2) Any such certificate as to a medical assessment matter is conclusive evidence as to the matters certified in any court proceedings or in any assessment by a claims assessor in respect of the claim concerned. … (9) A certificate is to set out the reasons for any finding by the medical assessor or assessors as to any matter certified in the certificate in respect of which the certificate is conclusive evidence. …"
In relation to matters falling within s 58(1)(d) of the MAC Act which are to be assessed by a medical assessor, the method for assessing the degree of impairment is governed by s 133 of that Act. Section 133(1) requires the assessment of the degree of permanent impairment of an injured person to be expressed as a percentage and subs (2) states that the assessment is to be made in accordance with the Motor Accidents Medical Guidelines issued for that purpose or, if there is no such guideline, then in accordance with the American Medical Association's Guides to the Evaluation of Permanent Impairment, Fourth Edition.
Section 44 of the MAC Act empowers SIRA to issue Motor Accidents Medical Guidelines. The 2018 Guidelines, which have been referred to above, are the relevant guidelines for present purposes. They have been issued by SIRA under s 44(1)(c) of the MAC Act, effective from 1 June 2018, and apply to motor accidents occurring between 5 October 1999 and 30 November 2017, including the 2015 motor accident in this case.
The essential issue in the present case was whether Ms Slade's injury and related impairment, as well as any consequent treatments, were causally related to the 2015 motor accident. How an assessor is to approach the issue of causation of permanent impairment is dealt with in various paragraphs of the 2018 Guidelines.
Paragraphs 1.5 to 1.7 of the 2018 Guidelines are found under the heading "Causation of injury" and provide (in the form applicable to the MAC Act): "1.5 An assessment of the degree of permanent impairment is a medical assessment matter under Section 58 (1)(d) of the Act. The assessment must determine the degree of permanent impairment of the injured person as a result of the injury caused by the motor accident. A determination as to whether the injured person's impairment is related to the accident in question is therefore implied in all such assessments. Medical assessors must be aware of the relevant provisions of the AMA4 Guides, as well as the common law principles that would be applied by a court (or claims assessor) in considering such issues. 1.6 Causation is defined in the Glossary at page 316 of the AMA4 Guides as follows: 'Causation means that a physical, chemical or biologic factor contributed to the occurrence of a medical condition. To decide that a factor alleged to have caused or contributed to the occurrence or worsening of a medical condition has, in fact, done so, it is necessary to verify both of the following: 1. The alleged factor could have caused or contributed to worsening of the impairment, which is a medical determination. 2. The alleged factor did cause or contribute to worsening of the impairment, which is a non-medical determination.' This, therefore, involves a medical decision and a non-medical informed judgement. 1.7 There is no simple common test of causation that is applicable to all cases, but the accepted approach involves determining whether the injury (and the associated impairment) was caused or materially contributed to by the motor accident. The motor accident does not have to be a sole cause as long as it is a contributing cause, which is more than negligible. Considering the question 'Would this injury (or impairment) have occurred if not for the accident?' may be useful in some cases, although this is not a definitive test and may be inapplicable in circumstances where there are multiple contributing causes."
As to the evaluation of "impairment … as a result of the injury caused by the motor accident", pars 1.9, 1.17 and 1.18 of the 2018 Guidelines also relevantly state: "1.9 Impairment is defined as an alteration to a person's health status. It is a deviation from normality in a body part or organ system and its functioning. Hence, impairment is a medical issue and is assessed by medical means. … 1.17 The medical assessor must evaluate the available evidence and be satisfied that any impairment: 1.17.1 is an impairment arising from an injury caused by the accident, and 1.17.2 is an impairment as defined in clause 1.9 (above). 1.18 An assessment of the degree of permanent impairment involves three stages: 1.18.1 a review and evaluation of all the available evidence including: ○ medical evidence (doctors', hospitals' and other health practitioners' notes, records and reports) ○ medico-legal reports ○ diagnostic findings ○ other relevant evidence 1.18.2 an interview and a clinical examination, wherever possible, to obtain the information specified in these Guidelines and the AMA4 Guides necessary to determine the percentage impairment, and 1.18.3 the preparation of a certificate using the methods specified in these Guidelines that determines the percentage of permanent impairment, including the calculations and reasoning on which the determination is based. The applicable parts of these Guidelines and the AMA4 Guides should be referenced."
How impairment is to be assessed when there is pre-existing impairment or subsequent injury is dealt with in pars 1.31 and 1.34, as follows: "Pre-existing impairment 1.31 The evaluation of the permanent impairment may be complicated by the presence of an impairment in the same region that existed before the relevant motor accident. If there is objective evidence of a pre-existing symptomatic permanent impairment in the same region at the time of the accident, then its value must be calculated and subtracted from the current WPI value. If there is no objective evidence of the pre-existing symptomatic permanent impairment, then its possible presence should be ignored. ... Subsequent injuries 1.34 The evaluation of permanent impairment may be complicated by the presence of an impairment in the same region that has occurred subsequent to the relevant motor accident. If there is objective evidence of a subsequent and unrelated injury or condition resulting in permanent impairment in the same region, its value should be calculated. The permanent impairment resulting from the relevant motor accident must be calculated. If there is no objective evidence of the subsequent impairment, its possible presence should be ignored."
It can be noted that, in relation to previous impairment, par 1.31 requires that the value of pre-existing symptomatic permanent impairment is to be subtracted from the current WPI value in order to evaluate the permanent impairment related to the relevant motor accident. In the case of subsequent impairment, however, no similar subtraction is mandated by par 1.34.
Finally, Pt 3.4 of the MAC Act also provides for review of a medical assessor's certificates. Under s 63(1), a party to a medical dispute may apply to the proper officer of SIRA to refer a medical assessment under this Part by a single medical assessor to a review panel of medical assessors for review. The other subsections of s 63 set out how such an application is to be dealt with.

The medical assessor's duty to give reasons

Section 61(9) of the MAC Act imposes a duty on a medical assessor, in a case such as the present, to set out in the certificate the reasons for any finding made by the assessor "as to any matter certified in the certificate in respect of which the certificate is conclusive evidence". Section 61(2) establishes that "[a]ny such certificate as to a medical assessment matter is conclusive evidence as to the matters certified … in any assessment by a claims assessor in respect of the claim concerned". The "matters certified" are those mentioned in s 61(1), which relevantly provides: "The medical assessor … to whom a medical dispute is referred is … to give a certificate as to the matters referred for assessment."
In the present case, the matters referred to the assessor in the present case were the three matters within s 58(1)(a), (b) and (d), which have been identified above.
Accordingly, by operation of s 61(9), the assessor was required to give reasons for each of his findings in relation to the three matters referred to him and these reasons were to be set out in the certificate given under s 61(1).
It was not in dispute in these proceedings that the assessor's reasons incorporated into his three certificates formed part of the "record" and that a failure by the assessor to give adequate reasons for his decisions would constitute an error of law on the face of the record: Wingfoot Australia Partners Pty Ltd v Kocak (2013) 252 CLR 480; [2013] HCA 43 (Wingfoot) at [28] and [55].
In addition, Wingfoot establishes a number of further propositions which are generally applicable in the present case, notwithstanding the differences in the wording of the statutory regime under consideration in that case compared to the provisions of the MAC Act and the 2018 Guidelines. These propositions are: 1. The extent of reasons required to be given in respect of a decision depends on the statutory context and factual circumstances in which the decision is made: Wingfoot at [45]; 2. What is to be set out in the statement of reasons in a case such as the present is the actual path of reasoning by which the assessor arrived at the opinion that he actually formed in relation to the medical assessment matters referred to him: Wingfoot at [48]; and 3. The standard required of a written statement of reasons given by a medical assessor under s 61(9) of the MAC Act is that the statement of reasons must explain the assessor's actual path of reasoning in sufficient detail to enable a court to see whether the opinion does or does not involve any error of law: Wingfoot at [55].
The statutory context relevant to a medical assessor making assessments under Pt 3.4 of the MAC Act includes the requirements of the 2018 Guidelines, by virtue of s 133(2) of that Act. These Guidelines include the three stages set out in par 1.18, which has been quoted above. The reasons should make clear that these stages have been followed.
In Campbelltown City Council v Vegan (2006) 67 NSWLR 372; [2006] NSWCA 284 at [121]-[122] Basten JA held, in a different but similar context to the present: "121. Where it is necessary for the Panel to make findings of primary fact, in order to reach a particular conclusion as to the existence, nature and extent of any physical impairment, it may be expected that the findings of material facts will be set out in its reasons. Where facts are in dispute, it may be necessary to refer to evidence or other material on which findings are based, but the extent to which this is necessary will vary from case to case. More importantly, where more than one conclusion is open, it will be necessary for the Panel to give some explanation of its preference for one conclusion over another. That aspect may have particular significance in circumstances where the medical members of a Panel have made their own assessment of the applicant's condition and have come to a different conclusion from that reached by other medical practitioners, as set out in reports provided to the Panel. 122. On the other hand, to fulfil a minimum legal standard, the reasons need not be extensive or provide detailed explanation of the criteria applied by medical specialists in reaching a professional judgment: see Soulemezis [v Dudley (Holdings) Pty Ltd (1987) 10 NSWLR 247] at 273-274 (Mahoney JA) and 281-282 (McHugh JA). At least, that will be so where the medical science is not controversial: if it is, a more expansive explanation may be required." (emphasis added)
The High Court also said in Wingfoot to say, at [55]: "If a statement of reasons meeting that standard discloses an error of law in the way the Medical Panel formed its opinion, the legal effect of the opinion can be removed by an order in the nature of certiorari for that error of law on the face of the record of the opinion. If a statement of reasons fails to meet that standard, that failure is itself an error of law on the face of the record of the opinion, on the basis of which an order in the nature of certiorari can be made removing the legal effect of the opinion."
This quotation gives some emphasis to the point that, if a medical assessor's reasons are inadequate, it may be difficult or impossible to determine whether the assessor has made an error of law.

Applicable principles in relation to causation

As provided in s 133(2) of the MAC Act, the assessor in this case was required to determine, inter alia, Ms Slade's degree of permanent impairment as a result of the injury caused by the motor accident in accordance with the 2018 Guidelines.
Paragraphs 1.5 and 1.6 of the 2018 Guidelines establish that an assessor making such an assessment must: 1. determine "whether the injured person's impairment is related to the accident in question"; 2. in doing so, be aware of "the common law principles that would be applied by a court (or claims assessor) in considering such issues"; 3. determine whether "a physical, chemical or biologic factor contributed to the occurrence of a medical condition [or impairment]" by verifying both that: 1. the factor could have caused the impairment - a medical determination; and 2. the factor did cause the impairment - a non-medical informed judgement; and 1. determine whether "the injury (and the associated impairment)" was caused or materially contributed to by the motor accident, noting that the accident does not have to be the sole cause as long as it is a contributing cause, which is more than negligible.
An assessor would also have to take into account the fact that par 1.17.1 of the 2018 Guidelines indicates that the question of causation of impairment turns on whether the impairment "arises from" an injury caused by the accident.
Finally, in the case of subsequent injuries, an assessor has to apply par 1.34 of the Guidelines when "impairment in the same region … has occurred subsequent to the relevant motor accident". In this situation: 1. if there is objective evidence of a subsequent and unrelated injury or condition resulting in permanent impairment in the same region, the value of the permanent impairment is to be calculated; and 2. the value of the permanent impairment resulting from the relevant motor accident is also to be calculated.
As has been noted above, it is significant that, unlike the situation under par 1.31, the assessor is not required or directed to subtract the whole or any part of the value of the subsequent impairment from the value of the current impairment. In fact, par 1.34 gives no specific guidance to an assessor as to how the values calculated in accordance with that paragraph are to be used. This being so, the common law principles that would be applied by a court in dealing with such a situation, can provide guidance, as envisaged by pars 1.5 to 1.7 of the 2018 Guidelines.
In the context of determining questions of causation in relation to motor accidents in accordance with "the … principles that would be applied by a court (or claims assessor) in considering such issues", the reference in par 1.5 to "common law principles" is to be understood as referring to the legal principles that courts or claims assessors are required to apply in determining causation. This includes not only common law principles, in the strict sense, [1] but also such principles as modified or explained by statutory provisions, such as s 5D of the Civil Liability Act 2002 (NSW) (CL Act), where applicable. This approach is consistent with Windeyer J's observation in Gammage v The Queen (1969) 122 CLR 444 at 462; [1969] HCA 68 that: "for the present purposes [of that case concerning the law of homicide], it is misleading to speak glibly of the common law in order to compare and contrast it with a statute. In any consideration of common-law rules it is necessary to take one's stand at some point of time. It is necessary too to be clear whether what is being spoken of as the common law at that point of time comprehends all statutory modifications of it then in force or only its pristine form".
The approach is also consistent with the remarks of Campbell J in Owen v Motor Accidents Authority of NSW [2012] NSWSC 650 at [27] where it was held that: "the question to be assessed [under the previous Motor Accidents Medical Guidelines which were relevantly in substantially the same terms as the 2018 Guidelines] is one of legal causation involving mixed questions of fact and law arising principally from the law of negligence as modified by Civil Liability Act 2002, s.5 D. (See s.3B(2))".
Section 5D of the CL Act relevantly provides: "(1) A determination that negligence caused particular harm comprises the following elements - (a) that the negligence was a necessary condition of the occurrence of the harm (factual causation), and (b) that it is appropriate for the scope of the negligent person's liability to extend to the harm so caused (scope of liability). … (4) For the purpose of determining the scope of liability, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party."
An indication of the nature of the causal connection between the impairment and the motor accident relevant under the 2018 Guidelines, when determining the degree of impairment attributable to a motor accident under s 58(1)(d) of the MAC Act, is given by the references to whether the injured person's impairment "is related to the accident", in par 1.5, or "arises from an injury caused by the accident" in par 1.17.1. These references may also be of assistance in addressing the scope of liability element of causation under s 5D(1)(b) CL Act.
Furthermore, and specifically in relation to the situation covered by par 1.34 of the 2018 Guidelines, there are common law principles that address the problem of subsequent injuries and impairment and how the values required to be calculated under that paragraph might be used to determine the degree of WPI "as a result of the injury caused by the motor accident" where there are subsequent injuries or impairment.
These principles were set out in the judgment of Malcolm CJ in State Government Insurance Commission v Oakley (1990) Aust Torts Rep 81-003; 10 MVR 570 (Oakley) and have been accepted by the Court of Appeal in cases such as Caltex Tanker Co (Aust) Pty Ltd v Kerr [1999] NSWCA 115 at [29]-[30]; Falco v Aiyaz; Falco v Falzon [2015] NSWCA 202 (Falco) at [13] and [94]; 71 MVR 454; and Secretary, New South Wales Department of Education v Johnson [2019] NSWCA 321 at [70] and [130]. In Oakley, Malcolm CJ said (at 67,577): "where the negligence of a defendant causes an injury and the plaintiff subsequently suffers a further injury the position is as follows: (1) where the further injury results from a subsequent accident, which would not have occurred had the plaintiff not been in the physical condition caused by the defendant's negligence, the added damage should be treated as caused by that negligence; (2) where the further injury results from a subsequent accident, which would have occurred had the plaintiff been in normal health, but the damage sustained is greater because of aggravation of the earlier injury, the additional damage resulting from the aggravated injury should be treated as caused by the defendant's negligence; and (3) where the further injury results from a subsequent accident which would have occurred had the plaintiff been in normal health and the damage sustained include [sic] no element of aggravation of the earlier injury, the subsequent accident and further injury should be regarded as causally independent of the first."
Sackville AJA in Falco at [94] and [95] noted that: "94. … Malcolm CJ observed that the second proposition covers what have been described as 'increased vulnerability' cases. In these cases, the plaintiff does not recover the full damages resulting from the later accident, 'but only those extra consequences of the second injury due to the existence of the first injury'. 95. The Second Accident caused relatively minor physical injuries to the appellant but led to her developing a psychiatric condition. The primary Judge found that the First Accident predisposed the appellant to an increased psychological reaction to the Second Accident. Consistently with the principles stated in SGIC v Oakley, it may have been open to the primary Judge to find that all or nearly all of the psychiatric damage sustained by the appellant in and after 2004 was causally related to the First Accident. The extent of the causal relationship would depend on his Honour's findings as to how far the appellant's psychiatric condition could be attributed to the vulnerability created by the First Accident. If his Honour did find a causal relationship between the First Accident and the appellant's psychiatric condition, the finding would not preclude Mr Falzon also being held liable for the psychiatric damage on the ground that the Second Accident was a concurrent cause of that damage". (footnotes omitted)
These observations provide an example of how the principles in Oakley should be applied in a case such as the present.
Indeed, it appears to me that par 1.34 of the 2018 Guidelines (and the corresponding provision in the previous version of the guidelines) may have been drafted with these common law principles in mind.
The situation covered by par 1.34 is where "there is objective evidence of a subsequent and unrelated injury or condition resulting in permanent impairment in the same region". It has been held that the words "unrelated injury or condition" in this context refer to the event causing the subsequent injury, not the medical description of the subsequent injury: GIO General Limited v Smith [2011] NSWSC 802 at [49] (Hoeben J, as his Honour then was); 59 MVR 69. This is consistent with the principles in Oakley, which depend on whether the subsequent event was related or unrelated to the earlier accident, based on whether the subsequent event would or would not have occurred had the plaintiff not been in the physical condition caused by the earlier accident.
The injuries and damage or impairment covered by the Oakley principles are, like the impairment to be assessed under par 1.34, injuries and damage or impairment that result from a subsequent event. The first Oakley category concerns events or accidents that would not have occurred but for a previous relevant event in which the claimant had been injured. Thus, the first category applies to a "related" injury or condition. The second and third Oakley categories, however, concern injuries resulting from a subsequent event that "would have occurred had the plaintiff been in normal health", which is, in other words, an "unrelated event" that leads to "subsequent and unrelated injury" within the meaning of par 1.34. The subsequent event and the associated injury or condition is "unrelated" because that event was not brought about by, or causally related to, the claimant's condition as a result of the earlier accident.
When the Oakley principles speak of "damage" and "aggravation", on the one hand, and "injury", on the other, in clauses such as "but the damage sustained is greater because of aggravation of the earlier injury", this reflects the distinction between "impairment" and "injury", as those terms are used in the MAC Act and the 2018 Guidelines. I do not accept Mr Rewell's submission to the effect that, while an injury, PTSD, was caused by the 2015 motor accident, because there was no impairment resulting from this injury before the 2016 near miss, there was no impairment which resulted from the PTSD caused by the 2015 motor accident.
In a situation such as the present, the second and third categories in Oakley provide common law principles to be applied by a medical assessor when determining, in accordance with the 2018 Guidelines, to what extent damage or impairment have been caused by injury suffered in an earlier motor accident when a subsequent unrelated event leads to further relevant damage or impairment. It is for this reason that par 1.34 requires the medical assessor to calculate: (a) the value of the permanent impairment resulting from the subsequent unrelated injury; and (b) the value of the permanent impairment resulting from the relevant motor accident, but does not require the assessor to subtract one value from the other in every case. Such a subtraction might be appropriate if the situation fell within the third category in Oakley but might be entirely inappropriate in situations within the second Oakley category.
In oral submissions, Mr Rewell submitted in effect that it would place an impossible burden on a medical assessor to do the exercise the medical assessor is required to do as in this case by par 1.34 of the 2018 Guidelines and then to apply the principles in Oakley. This submission should not be accepted.
The Court of Appeal's decision in Secretary, New South Wales Department of Education v Johnson [2019] NSWCA 321 provides an illustration, in a different but quite similar context, of what is required of a medical assessor (or review panel) when considering a claim involving an earlier accident, such as the 2015 motor accident, which led to psychological injury, and a subsequent "unrelated" event, such as the 2016 near miss, which also led to psychological injury and impairment.
In Johnson, the worker sustained psychological injury in 2014 during the course of her employment with the Secretary of the Department of Education. Subsequently, in 2017, the worker sustained psychological injury while working with another employer, Aboriginal Hostels Ltd. The worker claimed lump-sum compensation under the Workers Compensation Act 1987 (NSW). This claim required an assessment to be made of the worker's WPI. Certificates from approved medical specialists (AMSs) certified that the worker's WPI was 19% and 17%. Either percentage would have entitled the worker to lump-sum compensation. The Secretary requested the matter be referred to an Appeal Panel of the Workers Compensation Commission on the basis that the latter AMS certificate contained a demonstrable error. The Appeal Panel determined that the certificate should be revoked and a new medical assessment certificate issued certifying that the percentage WPI of the worker as a result of the first injury was 6%. If that assessment were to stand, the worker would not have been entitled to lump-sum compensation.
On an application under s 69 of the Supreme Court Act 1970 (NSW), Garling J concluded that the certificate issued by the Appeal Panel contained an error on its face and the worker was entitled to succeed in her claim. His Honour concluded that the decision that ought to have been reached by the Appeal Panel was that the worker's WPI was 19% and not 6%, as a result of the first injury. Accordingly, orders were made quashing the decision of the appeal panel and remitting the matter to the Registrar to be dealt with in accordance with law. The Secretary sought leave to appeal. Leave to appeal was granted but the appeal was dismissed.
The Court of Appeal noted that problems of causation such as arise in the present case are not new to the law and were even raised in relation to liability for damnum iniuria datum under the Lex Aquilia, which dates from the middle of the Roman Republic. [2]
In Johnson, the Court of Appeal was concerned with the phrase "the degree of permanent impairment of the person as a result of an injury" as it appears in both ss 319(c) and 326(1)(a) of the Workplace Injury Management and Workers Compensation Act 1998 (NSW). This is, in substance, identical to the phrase in s 58(1)(d) of the MAC Act, "the degree of permanent impairment of the injured person as a result of the injury caused by the motor accident", which applies in the present matter. In relation to that phrase, Emmett AJA explained, at [55]: "that composite phrase requires an enquiry as to the causal connection between the degree, or percentage, of assessed permanent impairment of a worker, on the one hand, and the compensable injury, on the other. That is to say, it was necessary for the AMS and the Appeal Panel to assess the degree, or percentage, of whole person impairment of the Worker that was caused by or is attributable to the First Injury. In doing so, common law principles of causation in tort are to be applied".
Substantially the same approach is to be applied in the present case, having regard to the relevant provisions of the MAC Act and the 2018 Guidelines.
His Honour accepted, at [70], that the principles derived from State Government Insurance Commission v Oakley, which have been referred to above, were the applicable principles. It was not suggested that applying these principles was a task beyond the ability of the medical assessors and the Appeal Panel of the Workers Compensation Commission.
Simpson AJA agreed with Emmett AJA's conclusion and her Honour's reasons are worth quoting at some length. From [129] to [135], her Honour said: "129. It was not in issue that the task committed to the Appeal Panel involved an assessment of the degree to which the respondent's unquestioned permanent impairment was attributable to ("resulted from") the injury she suffered [while in the Secretary's employ]. That assessment was complicated by her experiences while employed by Aboriginal Hostels. 130. In my opinion there is considerable substance in the appellant's reliance on the three categories stated by Malcolm CJ in Oakley. Those categories have been adopted by this Court in Jefferies v Roads and Traffic Authority of NSW [1997] NSWCA 167 (NSW Court of Appeal, 28 November 1997, unrep); Caltex Tanker Co (Aust) Pty Ltd v Robert Kerr [1999] NSWCA 115; Government Insurance Office of NSW v Aboushadi [1999] NSWCA 396; [1999] Aust Torts Reports 81-531. In the last of these cases Mason P, with whom Meagher JA and Barr J agreed, said: "23 … the question at issue is the extent of liability of the first tortfeasor in a situation where the continuing adverse impact of the first tort is discernible. It is not the law that the commission of a second tort, affecting an already vulnerable plaintiff, by itself puts an end to the liability of the defendant responsible for the first tort …" 131. His Honour went on to refer to the judgment of Windeyer J in Faulkner v Keffalinos (1970) 45 ALJR 80 at 85. Windeyer J said: "There is I think a critical distinction between a supervening happening that prevents a particular damage occurring as a result of the tort and a supervening happening that causes the harm caused by the tort to have added gravity. In the first class of case the supervening event diminishes the damages which flow from the tort: in the second class it merely adds to them, so that the tortfeasor responsible for the first accident remains liable for the harm he caused, which is not merged in the combined result of his wrongdoing and the later event. The distinction is not always either easily made or preserved." 132. The consequence of those authorities is that, in the circumstances of this case, a necessary part of the Appeal Panel's task was to consider, in the light of the medical evidence, into which of the three Oakley categories the respondent's case fell. That analysis was not undertaken by the Appeal Panel. 133. The appellant's argument proceeded on the assumption (unwarranted in my opinion, and without adequate analysis) that only the third Oakley category was relevant. 134. It may be accepted that the first Oakley category can be excluded. There is no reason in the evidence to think that the injury the respondent alleged she suffered in her employment at Aboriginal Hostels would not have occurred but for the injury suffered [while in the Secretary's employ]. At least, it may be assumed that the events that she claimed gave rise to that injury would have occurred, regardless of the history of her previous injury. But there is much in the evidence that would support the application of the second Oakley category. While the events at Aboriginal Hostels would, in all probability, have occurred had the respondent been in normal health, there was medical evidence that the respondent was, by reason of events [while in the Secretary's employ], in a vulnerable position, leaving her exposed to a greater level of damage resulting from subsequent events. That issue was not addressed by the Appeal Panel. 135. What was required on the part of the Appeal Panel was a careful analysis of all of the evidence. I do not pretend that task was other than one of some complexity. The Appeal Panel's reasons do not indicate that that task was undertaken. It was insufficient for the Appeal Panel to record and summarise, as it did, the various medical reports. …". (emphasis added)
In my view, substantially the same reasoning applies in the present case. In relation to issues of causation, the medical assessor was required to undertake a careful analysis of all the evidence and, in light of that evidence, consider: 1. whether what occurred in the 2015 motor accident could have caused, or contributed to, the impairment resulting from Ms Slade's PTSD, which is a medical determination, as specified in par 1.6(1) of the 2018 Guidelines; and then consider: 1. whether what occurred in the 2015 motor accident did cause, or contribute to, the impairment caused by Ms Slade's PTSD, which is a non-medical determination, as specified in par 1.6(2), noting that the motor accident does not have to be a sole cause as long as it is a contributing cause, which is more than negligible, as provided in par 1.7.
In carrying out the second element of this process in a case where there is a subsequent, unrelated event leading to relevant impairment, the assessor was required to apply pars 1.5, 1.7 and 1.34 of the 2018 Guidelines, as informed by the principles in relation to causation that would be applied by a court in considering such issues, including: 1. s 5D(1)(a) and (b) of the CL Act, which provisions are reflected to some extent in pars 1.6 and 1.7 of the 2018 Guidelines; and 2. the principles in Oakley, which assist to determine how the permanent impairment resulting from the PTSD caused by the earlier motor accident is to be determined based on the values calculated, as required by par 1.34 of the Guidelines, and in light of s 5D(1)(b) of the CL Act.
The principles in Oakley establish, relevantly for present purposes, in effect that: 1. Where the further injury or impairment results from a subsequent incident, which would not have occurred had the claimant not been in the condition caused by the earlier motor accident, the added damage should be treated as caused by the earlier motor accident. In this situation, par 1.34 is not engaged because the "injury or condition" is not "unrelated". 2. Where the further injury or impairment results from a subsequent incident, which would have occurred even if the claimant had not been in the condition caused by the earlier motor accident, but impairment is sustained or is greater because of aggravation of the earlier injury, the additional impairment resulting from the aggravated injury should be treated as caused by the earlier motor accident. 3. Where the further injury or impairment results from a subsequent incident, which would have occurred even if the claimant had not been in the condition caused by the earlier motor accident, but the impairment sustained includes no element of aggravation of the earlier injury, the subsequent incident and further impairment should be regarded as causally independent of the earlier motor accident.
In the latter two situations, par 1.34 is engaged because the "subsequent … injury or condition" is "unrelated" to the first motor accident, as that expression is to be understood in that paragraph. The Oakley principles provide a structure of analysis which is of assistance when applying the approach referred to in pars 1.5 - 1.7 and 1.34 of the 2018 Guidelines and s 5D(1)(b) of the CL Act.
The application of the Oakley principles in this way is consistent not only with the approach in Johnson but also with previous motor accident cases dealing with the predecessor of par 1.34, which was in identical terms in the previous version of the guidelines. Those cases included, for example: GIO General Limited v Smith [2011] NSWSC 802 at [54]; Smith v Insurance Australia Ltd [2018] NSWSC 1606 at [37] to [40]; and Coventry v Insurance Australia Ltd T/as NRMA Insurance [2019] NSWSC 1096 at [56] to [61]; 89 MVR 298. It can be noted that although Campbell J in Coventry did not refer expressly to Oakley, his Honour did refer to essentially the same principles contained in other authorities, at [57] to [59].

Did the assessor provide adequate reasons?

Turning now to consider the assessor's reasons for his findings in his certificates, I note that he found that Ms Slade suffered an injury, chronic PTSD, which was caused by the 2015 motor accident, and, after the 2016 near miss, she suffered psychological symptoms amounting to 19% WPI, which were caused by or related to the chronic PTSD. It was also found in effect that she would not have had that PTSD or the need for treatment after the 2016 near miss "without the [2015 motor] accident". It is implicit in the assessor's reasons that the need for treatment only arose after the 2016 near miss because of her degree of impairment and that impairment would not have occurred without the 2015 motor accident.

The certificate in MAS matter number 2018/02/3778

Although the medical assessor concluded that Ms Slade's WPI after the 2016 near miss was 19%, the WPI which resulted from the 2015 motor accident was found to be 0%. This might be correct if the present case fell within the third category in Oakley. It is far from obvious, however, that this is so. For Ms Slade's situation to fall within the third Oakley category, it would have to be the case that the damage or impairment sustained by Ms Slade as a result of the 2016 near miss included "no element of aggravation of the earlier injury [chronic PTSD]". The assessor made no such finding. Indeed, his reasons indicate that he was of the contrary view.
In the circumstances, it appears more likely that the present case would fall within the second Oakley category since the damage or impairment suffered as a result of the 2016 near miss appears to have been wholly because of "aggravation" of the PTSD, which was the injury which the assessor found Ms Slade had suffered in the 2015 motor accident.
However, it is difficult, if not impossible, to express any concluded view on which of the Oakley categories the assessor determined that Ms Slade's case fell into and whether the assessor applied the correct legal principles because the reasons in this case do not disclose his actual path of reasoning.
The assessor's reasons contain no adequate explanation of how he reached the conclusion that the degree of permanent impairment as a result of the injury caused by the 2015 motor accident was less than 10%, namely 0%. He did not explain why he, in effect, subtracted the 19% "Subsequent % permanent impairment" from the 19% "Current % permanent impairment" to arrive at the 0% "Final % permanent impairment". To the extent that any of his relevant reasoning was disclosed, it was not in sufficient detail to enable a court to see whether his conclusion in relation to the s 58(1)(d) matter as to the degree of impairment as a result of the injury caused by the 2015 motor accident did or did not involve any error of law.
The subtraction which the assessor carried out was not the only course open to him under par 1.34, as the decision in GIO General Limited v Smith [2011] NSWSC 802 at [54] makes clear. Applying the principles in Oakley, it was open to conclude that the value of the permanent impairment resulting from the 2015 motor accident was 19%. In these circumstances, it was necessary for the assessor to give some explanation of his preference for his conclusion over the conclusion that no subtraction should be made from the degree of current impairment because of the degree of impairment which arose after the 2016 near miss as a result of the chronic PTSD caused by the 2015 motor accident.
Put another way, the assessor made essentially the same error as the Appeal Panel in Johnson. A necessary part of the assessor's task was to consider, in the light of the medical evidence, into which of the three Oakley categories Ms Slade's case fell and then to determine the extent of the relevant causal connection between the WPI at the time of the assessment and the 2015 motor accident. That analysis was not undertaken by the assessor.
For all these reasons, it appears to me that the assessor failed to give adequate reasons for his decision to issue the certificate in MAS matter number 2018/02/3778. Given s 61(9) of the MAC Act and the other circumstances of the case, this failure to give adequate reasons amounts to an error of law on the face of the record.
On this basis, the certificate in MAS matter number 2018/02/3778, that the injury, being Chronic Post-traumatic Stress Disorder (PTSD), caused by the 2015 motor accident gave rise to a permanent impairment which was not greater than 10%, is liable to be set aside.

The two certificates in MAS matter number 2018/01/3773

Further, in relation to the s 58(1)(b) matter referred to the assessor, concerning whether the treatments claimed by Ms Slade "relate[d] to the injury caused by the [2015] motor accident", this also turned on the question of causation of her impairment and the consequent need for treatment. While the assessor found that some of the treatments were so related, he also found that: "Gratuitous personal and domestic assistance and Paracetamol are not causally related to the psychiatric injury as they are not mainstream treatments of PTSD."
Such personal and domestic assistance appear to me potentially to fall within par (d) of the definition of "treatment" in s 42 of the MAC Act: "the provision of attendant care services", as the assessor apparently accepted.
The assessor's reasons relevantly stated: "Gratuitous personal and domestic assistance is not causally related and therefore not reasonable and necessary. … 0-8 tablets of 500 mg Paracetamol is not causally related and therefore not reasonable and necessary."
Despite the requirements of par 1.18.1 of the 2018 Guidelines and s 61(9) of the MAC Act, the assessor did not refer in his reasons to any consideration being given to the report of the occupational therapist, Ms Stevenson, which dealt in detail with gratuitous personal and domestic assistance and how it was related to Ms Slade's PTSD and impairment. Nor did he refer to the last paragraph of Dr Parsonage's report which effectively endorsed Ms Stevenson's conclusions.
As the personal and domestic assistance were said by those experts to be the result of, and related to, Ms Slade's PTSD and consequent impairment, it was at least open for the assessor to conclude that such assistance and medication were related to the injury caused by the 2015 motor accident, contrary to his expressed conclusion. In these circumstances, it was necessary for the assessor to give some explanation for his preference for his conclusion over the other conclusion that was available. However, the assessor did not even refer to the evidence of Ms Stevenson and Dr Parsonage in these regards or explain why he rejected it. Nor did he otherwise disclose the actual path of reasoning that led him to his conclusion.
Further and in particular, the assessor did not explain how his assertion that the personal and domestic assistance and medication with paracetamol were not "mainstream treatments of PTSD" led to the conclusion that they were not caused by or related to PTSD, which was the injury caused by the 2015 motor accident. It does not follow merely from the fact, if it be the fact, that the relevant "treatments" were not "mainstream", that the treatments were not "relate[d] to the injury caused by the motor accident". [3] The conclusion was not so self-evident that no explanation was required.
For all of these reasons, I do not accept that the assessor's reasons in relation to the matter under the s 58(1)(b) which had been referred to him were sufficient in the circumstances. Thus, there is an error of law on the face of the record and his certificate concerning this matter is liable to be set aside.
As to the matter under s 58(1)(a) which was referred to the assessor for assessment, this included whether that assistance and treatment were "reasonable and necessary in the circumstances". From his reasons, relevant portions of which have been quoted above, it appears that the assessor's conclusion in this regard was based entirely on the conclusion in relation to the s 58(1)(b) matter. The reasoning was to the effect that because the assistance and treatment were not causally related to the 2015 motor accident, therefore they were not reasonable and necessary. If the conclusion in relation to the s 58(1)(b) matter is liable to be set aside because of a failure to give adequate reasons, then the conclusion in relation to the s 58(1)(a) matter will also fall with it.
Although there were unchallenged aspects of the two certificates in MAS matter number 2018/01/3773 (which included both the s 58(1)(a) and (b) matters), the findings in those certificates concerning gratuitous personal and domestic assistance and treatment with paracetamol are liable to be set aside because of a failure to give adequate reasons. The parties accepted that the certificates could not, however, be set aside only in part.
Consequently, the certificate in MAS matter number 2018/01/3773, that certain treatments listed in the certificate related to the injuries caused by the 2015 motor accident and other treatments did not, and the certificate in MAS matter number 2018/01/3773, that certain treatments listed in the certificate were reasonable and necessary in the circumstances and other treatments were not, are both liable to be set aside.

Should the certificates be set aside?

It was not submitted that, even if the certificates were liable to be set aside, the Court in its discretion should nonetheless refuse to grant relief. Further, I can discern no reason for refusing relief in the circumstances of this case.
Accordingly, I propose to order that the three certificates should be set aside and the matter should be remitted to SIRA for the matters to be referred to a medical assessor for assessment in accordance with law.

Review of the proper officer's decision

Having concluded that the medical assessor's three certificates should be set aside for the reasons given above, it is neither necessary nor appropriate to consider the application so far as it relates to the proper officer's decision to refuse to refer the application for review of the medical assessment to a review panel, under s 63 of the MAC Act.

Costs

The plaintiff has been successful on her application. There do not appear to me, as presently advised, to be any circumstances that would render it inappropriate for costs to follow the event, in the usual way.
Thus, I propose to order that the defendant pay the plaintiff's costs as agreed or assessed. If a party wishes to make an application for a different costs order, this may be done by notice of motion filed within 14 days of entry of the orders, under r 36.16(3A) of the UCPR.

Orders

Accordingly, the orders of the Court are: 1. The time in which the plaintiff may commence the proceedings for judicial review is extended to 15 November 2019. 2. The Certificate in MAS matter number 2018/02/3778 given by the fourth defendant on 24 April 2019, as to whether the degree of permanent impairment of the injured person as a result of the injury caused by the motor accident is greater than 10%, is set aside. 3. The Certificate in MAS matter number 2018/01/3773 given by the fourth defendant on 24 April 2019, as to whether the treatment provided or to be provided to the injured person relates to the injury caused by the motor accident, is set aside. 4. The Certificate in MAS matter number 2018/01/3773 given by the fourth defendant on 24 April 2019, as to whether the treatment provided or to be provided to the injured person was or is reasonable and necessary in the circumstances, is set aside 5. The matters are remitted to the second defendant to be referred for assessment under Pt 3.4 of the Motor Accidents Compensation Act 1999 (NSW) according to law. 6. The first defendant is to pay the plaintiff's costs as agreed or assessed.

Endnotes

That is those principles of law created by the Courts as opposed to legal principle enacted by statute. See generally Dietrich v The Queen (1992) 177 CLR 292 at 318-319 (Brennan J); [1992] HCA 57.
Secretary, New South Wales Department of Education v Johnson [2019] NSWCA 321 at [48].
The relevant matter under s 58(1)(b) of the MAC Act referred to the assessor in the present case included "whether any such treatment relates to the injury caused by the [2015] motor accident [namely PTSD]". DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated. Decision last updated: 07 August 2020

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