NSW workers compensation case note
Walton v State of NSW [2026] NSWSC 824: section 323 deductions and WPI
The NSW Supreme Court set aside a Medical Appeal Panel decision that reduced Ellen Walton’s whole person impairment from 15% to 14%. The problem was not that a section 323 deduction can never be made. It was that the Panel had not first decided whether the pre-existing thoracic degeneration actually made the degree of impairment greater than the impairment caused by the work injury alone.
General information only. This case note is not legal advice and does not predict the result of another claim.
Overview
What did the Supreme Court decide?
The Court found a jurisdictional error in the Appeal Panel’s reasoning. Before applying the assumed 10% deduction in section 323(2), the Panel had to address the causal question in section 323(1): did the pre-existing condition contribute to the degree of permanent impairment? The matter was sent back to a differently constituted Panel for redetermination.
- Degenerative findings do not automatically justify a 10% WPI deduction.
- The judgment did not finally determine Ms Walton’s WPI or rule out a deduction on reconsideration.
- The one percentage point mattered because 15% WPI is the section 151H gateway for a work injury damages claim.
Case details
- Court
- Supreme Court of New South Wales, Common Law Division
- Judge
- Elkaim AJ
- Hearing date
- 2 July 2026
- Decision date
- 14 July 2026
- Key provisions
- Workplace Injury Management and Workers Compensation Act 1998 (NSW), ss 323 and 328; Workers Compensation Act 1987 (NSW), s 151H; Supreme Court Act 1970 (NSW), s 69
- Central issue
- Whether the Appeal Panel could apply a 10% deduction for a pre-existing thoracic condition without determining that it contributed to the degree of permanent impairment.
What happened?
Ms Walton was an enrolled nurse. On 10 June 2022, she slipped on urine near a patient’s bed, struck her left knee and twisted while trying to hold the bed. Her claim involved the left knee, scarring and the thoracic spine.
A CT scan taken on 11 July 2022 recorded thoracic kyphosis, an old anterior wedge fracture at T8, degenerative changes and mild T7/8 facet osteoarthritis. Those findings became important when the employer argued that part of the permanent impairment was attributable to a pre-existing condition.
The Medical Assessor assessed 15% WPI: 7% for the knee, 1% for scarring and 7% for the thoracic spine. The thoracic assessment comprised 5% for DRE Thoracic Category II plus 2% for activities of daily living.
How the WPI changed on appeal
The Appeal Panel applied the assumed one-tenth deduction in section 323(2) to the thoracic component. After rounding, the thoracic rating fell from 7% to 6%, and the combined assessment fell from 15% to 14%.
| Assessment component | Medical Assessor | Appeal Panel |
|---|---|---|
| Left knee | 7% WPI | 7% WPI |
| Scarring | 1% WPI | 1% WPI |
| Thoracic spine | 7% WPI | 6% WPI after deduction and rounding |
| Combined result | 15% WPI | 14% WPI |
These figures describe the assessments in this case. They are not a calculator or estimate for another worker.
Why was the deduction challenged?
Section 323 is concerned with the degree of permanent impairment. It is not enough to identify an old fracture, degeneration or previous symptoms. The decision-maker must determine whether the earlier condition or injury contributed to the impairment being assessed, and if so, by how much.
The employer relied on the imaging and medical history. Ms Walton argued that the Panel had moved from those findings to the assumed 10% deduction without deciding the required causal question. That gap was especially important because the Panel accepted a DRE Category II assessment but did not adequately explain which part of the impairment was increased by the pre-existing condition.
What the Court found
Elkaim AJ held that the Panel’s failure to determine whether the pre-existing condition made the degree of impairment greater was a jurisdictional error. A contribution to symptoms or pain is not necessarily the same as a contribution to the degree of permanent impairment.
The assumed 10% deduction in section 323(2) does not replace the threshold inquiry in section 323(1). It becomes relevant only after a contribution to the degree of impairment has been established and the extent of that deduction would otherwise be difficult or costly to determine.
The Court declared the Panel decision void, set it aside and remitted the matter to a differently constituted Appeal Panel. It did not substitute a final medical percentage.
How section 323 should be approached
In practical terms, the reasoning requires the following questions to be kept separate:
- Identify the previous injury, condition or abnormality said to exist before the work injury.
- Determine, using medical evidence, whether it contributed to the degree of permanent impairment now being assessed.
- Only then determine the proportion to deduct. The one-tenth assumption may apply where the actual extent is too difficult or costly to determine, unless that assumption would be at odds with the evidence.
Why the DRE Thoracic Category II reasoning mattered
The thoracic spine was assessed in DRE Category II. A DRE category is not simply an imaging label. The assessor must connect the accepted injury and relevant clinical findings to the category criteria under the applicable impairment guidelines.
The Court’s concern was not to perform a new medical assessment. It was that the Panel had not explained how the pre-existing degeneration increased the degree of impairment represented by the accepted DRE category and the additional activities-of-daily-living component. That missing reasoning affected whether section 323 could lawfully reduce the result.
Why the case matters in practice
- An insurer or employer cannot establish a section 323 deduction merely by pointing to words such as “degenerative”, “chronic” or “old” in a scan report. The medical reasoning should address the impairment actually being rated.
- For workers near a statutory threshold, a small deduction can change the available claim pathway. Here, the difference between 15% and 14% affected the section 151H threshold for work injury damages, although meeting that threshold would not by itself prove employer negligence or damages.
- A challenge should identify the precise reasoning error. It is not enough to say that the percentage feels unfair. The certificate, assessment method, clinical findings, prior history, submissions and Panel reasons need to be compared carefully.
What the judgment does not decide
The Court did not decide that Ms Walton must ultimately be assessed at 15% WPI. The new Panel may reach a different result if it applies the correct legal test and gives adequate reasons supported by the evidence.
The judgment also does not mean pre-existing degeneration can never be deducted. It confirms that the necessary causal finding must come first, and that the deduction must relate to the degree of permanent impairment rather than the mere presence of an earlier condition.
Documents to review in a section 323 dispute
The useful material depends on the body system and assessment method, but the file will often include:
- the Medical Assessment Certificate and any Appeal Panel certificate and reasons;
- the accepted injury description and insurer decision notices;
- pre-injury clinical notes, imaging and evidence of prior function or symptoms;
- post-injury imaging, examination findings and treating specialist opinions;
- the medico-legal reports explaining the impairment method and any proposed deduction;
- the parties’ written submissions identifying the alleged pre-existing contribution;
- a chronology showing the worker’s function before and after the workplace injury.
Orders made
- The Appeal Panel decision was declared void and set aside.
- The medical appeal was remitted to a differently constituted Appeal Panel for redetermination according to law.
- The employer was ordered to pay Ms Walton’s costs. No costs order was made against the Personal Injury Commission or Panel members.
Frequently asked questions
Does pre-existing degeneration automatically produce a 10% WPI deduction?
No. The decision-maker must first determine that the pre-existing condition contributed to the degree of permanent impairment. The assumed one-tenth deduction does not bypass that causal question.
Did the Supreme Court decide that Ms Walton has 15% WPI?
No. The Court set aside the Appeal Panel decision for legal error and sent the medical appeal to a different Panel. The final percentage remains to be redetermined.
Why did one percentage point matter?
Section 151H requires at least 15% permanent impairment for a work injury damages claim to proceed. Reaching 15% is a gateway only; negligence, economic loss and the other requirements still need to be established.
Can an old fracture or degenerative scan still support a deduction?
It may, depending on the medical evidence. The relevant question is whether and to what extent the earlier condition increased the degree of permanent impairment being assessed, not simply whether it appears on imaging.
What should be checked after a section 323 deduction?
Check the injury accepted by the insurer, the assessment method and category, the findings relied on, the prior medical history, the calculation, and whether the reasons explain the causal link between the earlier condition and the degree of impairment.
Official source
Read the judgment for the complete facts, submissions, reasons and orders. This case note is a summary of the published decision.
Related guides
Has a section 323 deduction changed your WPI result?
Send the assessment certificate, appeal reasons and the medical material relied on for the deduction. We can review what the decision actually says and the next practical step.