By Alan Wrigley and Caitlin Miller
Some recent court decisions serve as timely reminders of the fundamental principles relating to waiver of legal professional privilege.
This includes the care and attention that must be taken when dealing with privileged information and how privilege can be lost, either through deliberate or inadvertent acts.
All information that a lawyer receives from their client is considered “confidential”.
Some of that information will also be subject to legal professional privilege (also known as LPP or client legal privilege).
Legal professional privilege (LPP) is fundamental to the practice of law. The right for communications between a lawyer and their client to remain confidential and free from the scrutiny of others has existed for hundreds of years.
The rationale for LPP has always been that the privilege encourages full and frank disclosure between lawyers and their clients, which in turn facilitates the administration of justice and the representation of clients in legal matters.
Where LPP exists in a document, it is protected from compulsory disclosure. For a document to be classified as privileged, it must:
- have passed between a client and their lawyer;
- have been produced or brought into existence with the dominant purpose of being used to obtain legal advice (advice privilege) or for use in existing or anticipated litigation (litigation privilege);[1] and
- be confidential.
The party claiming privilege will have the onus of establishing its existence.[2]
Can LPP be waived?
Yes. Legal professional privilege in a document can be waived, either expressly or impliedly, so that the protection afforded by LPP is lost.
For example, where legal advice is deliberately disclosed to another party (thereby eroding confidentiality in the document) any LPP in that document will automatically be lost. This is known as ‘express’ waiver.
Other times, waiver of privilege will occur where the privilege-holder acts in a manner that is inconsistent with the privilege, thereby ‘impliedly’ waiving privilege. When asked to determine if privilege has been impliedly waived, Courts will consider whether it is unfair or misleading for a person to rely on legal professional privilege in circumstances where they have, at the same time, acted inconsistently with the privilege.
The Federal Court of Australia has recently handed down number of decisions concerning the implied waiver of privilege, which are considered below.
The Mastercard Asia decisions
In August 2025, the Federal Court of Australia released the following judgments in the same proceeding:
- Australian Competition and Consumer Commission v Mastercard Asia/Pacific Pte Ltd (No 2) [2025] FCA 1004 (ACCC v Mastercard (No 2)); and
- Australian Competition and Consumer Commission v Mastercard Asia/Pacific Pte Ltd (No 3) [2025] FCA 1043 (ACCC v Mastercard (No 3)).
Both of these judgments concerned an implied waiver of legal professional privilege by Mastercard Asia/Pacific Pte Ltd and Mastercard Asia/Pacific (Australia) Pty Ltd (together, Mastercard).
ACCC v Mastercard (No 2) – no waiver of LPP
The Australian Competition and Consumer Commission (ACCC) challenged claims of LPP made by Mastercard over, among other documents, email chains where Mastercard claimed LPP over portions of each email.
Mastercard had been issued with a notice from the ACCC to produce documents under section 155 of the Competition and Consumer Act 2010 (Cth).
Following a review of approximately 75,000 documents, Mastercard produced 7,437 documents to the ACCC in response to the notice. In the response, Mastercard expressly noted that it had sought to identify and exclude any privileged documents from production, but did not waive LPP in any document that was inadvertently disclosed.
The ACCC contended that Mastercard had acted inconsistently with a claim of privilege by producing the emails without claiming any form of privilege and by referring to one of the disputed emails by its document ID in a footnote of a voluntary submission made to the ACCC.
The Court was ultimately satisfied that Mastercard’s alleged waivers of privilege were inadvertent and privilege had not been waived.
ACCC v Mastercard (No 3) – waiver of LPP
In this application, the ACCC sought orders that Mastercard identify and provide further information about certain categories of documents, as well as to produce unredacted copies of the documents for inspection.
The ACCC submitted that Mastercard had waived privilege in respect of communications through affidavit evidence of two of Mastercard’s senior officers that contained express and implied assertions about the contents of other privileged communications.
The Court determined that Mastercard had waived privilege in respect of certain documents by filing and serving the two affidavits. The Court:
- considered that Mastercard’s affidavit material amounted to express or implied assertions about the contents of communications with other Mastercard officers and in-house counsel and that the communications became open to scrutiny and put the content of the communications in issue in a way that is inconsistent with the maintenance of confidentiality;[6] and
- was not persuaded that the affidavit evidence did not expressly refer to the existence of legal advice or that the assertions were not explicitly about and did not directly or explicitly disclose the content of any legal advice.[7]
Korea Midland Power Co Ltd v ACIRL Quality Testing Services Pty Ltd (No 2) [2025] FCA 987
ALS Limited (ALS) (which is not a party to the above proceeding) responded to a subpoena served by Korea Midland Power Co Pty Ltd (KMP) by producing, subject to claims of LPP, a preliminary report and a final report which had been prepared for ALS by McGrathNicol.
KMP challenged ALS’s claims of LPP over the reports and argued that to the extent that any privilege existed, it had been waived by ALS.
Following an enquiry received from the Australian Financial Review in February 2020, ALS engaged external lawyers to provide advice to ALS and McGrathNicol to conduct an investigation for the purpose of ALS obtaining legal advice.
Later that month, ALS released an ASX announcement confirming that ALS had appointed external advisors to conduct an independent, forensic investigation and which revealed some findings of McGrathNicol’s preliminary investigations. The announcement did not refer to McGrathNicol nor the purpose of the reports.
After receiving McGrathNicol’s final report, ALS released a further ASX announcement reporting on the outcome of the forensic investigation conducted by McGrathNicol.
The Court was satisfied that the McGrathNicol reports were subject to LPP and so, turning to the issue of an alleged waiver of LPP, the issue for the Court to determine was whether ALS (by its ASX announcements) had waived its right to maintain LPP.
The Court found that the publication by ALS of information from the McGrathNicol reports was for a forensic and commercial advantage which demonstrated a clear inconsistency between the publication of that information and the maintenance of confidentiality (and therefore, LPP in the reports). For that reason, the Court held that ALS had waived privilege with respect to parts of the McGrathNicol reports.
We regularly advise clients in relation to issues concerning legal professional privilege, including in the context of regulatory investigations. If you have any questions or require any assistance, please feel free to contact us.
Alan Wrigley is a Partner in the litigation and dispute resolution group at McCullough Robertson Lawyers, specialising in contractual disputes, commercial claims and regulatory matters.
Caitlin Miller is Litigation and Dispute Resolution Lawyer at McCullough Robertson Lawyers.
