Out-Law Analysis 2 min. read
Australian court decision has evidence strategy implications for commercial disputes
22 Sep 2025, 4:58 am
A recent decision by Australia’s Federal Court highlights the need for careful consideration of evidence if protecting privilege or confidentiality is a concern during commercial disputes. The case demonstrates an example of professional privilege being inadvertently waived during legal proceedings causing documents to be subject to disclosure or compulsory discovery.
In the case, the Australian Competition and Consumer Commission (ACCC) alleged that Mastercard Asia/Pacific (Australia) Pty Ltd (Mastercard) had engaged in anti-competitive conduct in breach of the Competition and Consumer Act 2010 (Cth). During the proceedings, Mastercard produced affidavits from senior officers which denied anti-competitive intent. Their affidavits referenced internal communications and decision-making processes, intended to demonstrate the officers’ state of mind during the negotiation of specific agreements relating to the alleged anti-competitive conduct.
The Federal Court confirmed that legal professional privilege – the principle that protects confidential communications between lawyers and clients – was waived in the case because the affidavits made implied assertions about otherwise privileged communications, resulting in Mastercard’s evidence being inconsistent with maintaining confidentiality.
Impact on commercial disputes
Privilege in commercial disputes can be waived if assertions are made that are likely to have been informed by confidential communications, even if they don’t explicitly refer to legal advice.
The test is whether it would be inconsistent to allow a party to rely on the assertions while still claiming confidentiality over the communications that underpin them. This principle is underpinned by considerations of fairness. If a party seeks to advance its case in this way, it is only fair that the opposing side has an opportunity to consider and test the relied-upon evidence, even if that evidence was considered privileged or confidential.
Another example where the courts have found inconsistency with the maintenance of confidentiality is in the circumstance where a party had used information from a report which was originally prepared for the purpose of lawyers providing legal advice in an open letter to shareholders. In that instance, the court held that privilege over the report had been waived.
This case highlights the need for careful consideration of a party’s case concept and the preparation of evidence if preserving privilege is a concern. While a party may be entirely comfortable using otherwise privileged materials to support its position, these decisions should be deliberate and considered in advance of the potential waiver.
The impact of these communications being available to the other party, and potentially the public, must be considered alongside their value as evidence in court.
Waiver cannot be walked back
The court also confirmed that a waiver of privilege cannot be walked back once it enters the evidentiary record even if it later withdrawn or not relied on, as waiver occurs when the material is filed.
Risk of subject matter disclosure
In its decision, the court found that the waiver applied to documents and communications that related to the subject matter of the issue, not just the specific documents referenced by Mastercard.
This point highlights the importance of assessing not only the specific documents relied upon in an affidavit, but also the broader implications of any subject related assertions relied on. Where a party seeks to rely on a narrow view of waiver, there is a risk this will be rejected by the court in favour of considerations of fairness and transparency.
Co-written by Caitlin Morris of Pinsent Masons.
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