Mega Jackpot Pty Ltd v Performance Property Services Group Pty Ltd and Ors [2026] VSC 416
Key Takeaways
- Filing and relying on an expert report may waive privilege over documents provided to that expert.
- It does not matter how the expert obtained the documents. If the expert used them to form an opinion, privilege may be lost.
- Courts are unlikely to allow a party to rely on an expert opinion while withholding documents that informed or influenced that opinion.
- Parties should carefully consider what material is provided to experts, particularly where documents contain privileged communications, annotations or legal commentary.
Background & Overview
In Mega Jackpot Pty Ltd v Performance Property Services Group Pty Ltd [2026] VSC 416 (22 June 2026), His Honour Justice Craig considered whether a party (the Plaintiff) could maintain a claim for legal professional privilege over documents that had been provided to, and relied upon by, its expert witness.
The underlying proceeding concerned allegations that clients had been diverted away from the Plaintiff’s business and that existing court orders had been breached.
The Plaintiff relied on an expert report prepared by Mr James Ridley (the Ridley Report). Appendix 2 to the Ridley Report identified documents that had been supplied to, and relied upon by, Mr Ridley in forming his opinions. Those documents included:
- a document described as ‘Master Copy: Court Orders Breached (Missing invoices); Mis-Representation and Diversion’
- ‘Scott’s Schedule’ and supporting documents which included information about diverted clients, and
- various ad hoc client notes prepared by the First Defendant.
The dispute over production
The Defendants sought urgent production of those documents before the deadline for filing their responsive expert evidence.
The Plaintiff resisted production. It argued that the ad hoc notes were already available to, or identifiable by, the Defendants. The Plaintiff also submitted that the Master Copy and Scott’s Schedule contained privileged communications and were heavily annotated by both the client and expert.
Decision and Legal Principles Applied
On 22 June 2026, Justice Craig ordered that all requested documents be produced and that the Plaintiff pay the Defendants’ costs of the application.
His Honour observed that the documents had not only been provided to Mr Ridley but were expressly identified as material on which he relied in preparing his report. Without access to those documents, neither the Court, the Defendants, nor the Defendants’ expert could properly understand the factual foundation of Mr Ridley’s opinions.
Justice Craig reaffirmed the established principle that a party will ordinarily waive privilege when it serves and relies upon an expert report that has been informed by privileged material. Referring to Australian Securities and Investments Commission v Southcorp Ltd [2003] FCA 804, His Honour noted the unfairness that would arise if a party were permitted to rely on an expert opinion while withholding documents, instructions or communications that may have influenced that opinion.
His Honour further confirmed that privilege generally cannot be maintained over documents used by an expert to form an opinion or prepare a report, regardless of how the expert obtained those documents.
Applying those principles, Justice Craig held that continuing to claim privilege over the Master Copy and Scott’s Schedule was inconsistent with filing and serving the Ridley Report. Because those documents had been provided to, and relied upon by, Mr Ridley, withholding them would create a ‘comprehensive unfairness’ to the Defendants. Any privilege attaching to those documents had therefore been waived.
His Honour also referred to sections 122 and 131A of the Evidence Act 2008 (VIC), together with Prince Removal & Storage Pty Ltd v Roads Corporation [2012] VSC 245, as supporting the conclusion that privilege had been waived once the report was filed and relied upon.
Why This Decision Matters
This decision is a timely reminder that engaging an expert witness can carry disclosure risks that may be overlooked during litigation preparation.
Parties commonly provide experts with background material, internal analyses, witness accounts, annotated documents and communications passing between solicitors and clients. However, once an expert relies on that material and the resulting report is filed or served in litigation, privilege over those documents may be lost.
The decision is particularly relevant to insurers, insureds and litigation practitioners who regularly instruct engineers, accountants, loss adjusters, building consultants and other expert witnesses.
Before briefing an expert, parties should:
- carefully consider whether privileged communications need to be provided at all
- separate factual source material from legal advice wherever possible
- avoid including unnecessary commentary or strategic observations in documents supplied to experts, and
- review expert briefs and supporting material before reports are finalised and served.
Once an expert report is relied upon in court, it may be too late to prevent disclosure of documents that influenced the expert’s reasoning. This decision demonstrates that courts will prioritise fairness and transparency in expert evidence over attempts to preserve privilege claims that are inconsistent with reliance on the expert’s opinion.
This article was written by Solicitor Devinda Goonesekera and Principal Lawyer Robert Minc. For further information or advice on any related matters, please contact Robert.
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