When a subpoena meets an arbitration: Lessons from Brackenridge v AT Brine & Sons Pty Ltd

Picture this: a private arbitration is underway between homeowners and their builder. The homeowners issue a subpoena requiring a third party to produce a wide range of project documents. That third party is no distant bystander. He is the homeowners’ own appointed architect, the very person who dealt with the builder throughout the project, approved variations, and held a central role under the building contract.

He objects. He says the subpoena is oppressive, lacks legitimate forensic purpose, and is effectively an attempt to force discovery on someone who is not a party to the arbitration.

What happens next?

In Brackenridge v AT Brine & Sons Pty Ltd [2026] WASC 338, the Supreme Court of Western Australia had to decide how far such a third party can push back and how much concrete evidence they need if they claim compliance would be too burdensome.

The judgment, delivered by Justice Lundberg, offers clear, practical guidance for anyone involved in arbitration disputes.

The background

The dispute concerned a residential construction project in Cottesloe. The plaintiff homeowners were locked in an arbitration with their builder, AT Brine & Sons Pty Ltd.

The builder claimed additional amounts under the building contract for provisional sums, variations and other costs. The homeowners counterclaimed for breach of contract, defective workmanship, non-compliance with the National Construction Code, delays, and damages.

Mr Blane Brackenridge (Blane), brother of the first plaintiff and brother-in-law of the second, had been engaged to provide architectural services for the project and was separately appointed as the “owner’s agent” under the building contract, with authority to make and sign all variations.

The homeowners sought and obtained a subpoena requiring Blane to produce eight categories of documents, ranging from architectural drawings and site diaries through to records of instructions, variation approvals and extension of time documents. The subpoena was issued pursuant to s 27A of the Commercial Arbitration Act 2012 (WA) and rule 17 of the Supreme Court (Arbitration) Rules 2016 (WA), with the permission of the arbitrator.

Blane, who was not a party to the arbitration, objected to the subpoena.

The challenge

Blane applied to set aside the subpoena under O 36B r 8A of the Rules of the Supreme Court 1971 (WA), advancing three grounds: that the documents lacked relevance and legitimate forensic purpose; that the subpoena was tantamount to an order for discovery against a third party; and that compliance would be oppressive.

The Court’s approach

Justice Lundberg began by surveying the well-established principles governing applications to set aside subpoenas. The Court may intervene where a subpoena amounts to an abuse of process, including where it lacks a legitimate forensic purpose, constitutes a fishing exercise, is deployed to obtain discovery from a third party, or where compliance would be oppressive.

Importantly, his Honour emphasised that the mere overlap between documents caught by a subpoena and those that might be sought in discovery does not, of itself, render the subpoena an abuse of process. Something more, described by his Honour as an “additional vice”, is required.

Relevance: a broad arbitration yields broad relevance

On the relevance objection, Justice Lundberg examined the pleadings in the arbitration and found that the issues in dispute were extensive: the scope of works, design compliance, the role and authority of Blane as appointed architect, variations, extensions of time, practical completion, defects, and the final account.

Given the breadth of these issues and Blane’s central role as both architect and owner’s agent, the categories of documents sought were plainly relevant. His Honour accepted that a degree of deference should be given to the arbitrator’s own assessment that the documents were relevant to the hearing and determination of the issues.

The Court rejected Blane’s relevance objections as positing “an unduly narrow conception as to apparent relevance which is simply not supported by the pleadings”: at [40].

Discovery: no “additional vice”

Blane argued that the parties to the arbitration were likely to have many of the same documents. The Court was unpersuaded. Three factors told against this objection: first, the parties had consented to directions providing for no general discovery in the arbitration; second, the defendant builder had not opposed the subpoena and the arbitrator had granted permission for it to be sought; and third, documents in Blane’s own possession may be probative of their existence, content and context in ways that copies held by the parties may not be.

Oppression: where conjecture falls short

Perhaps the most instructive aspect of the judgment is the Court’s treatment of the oppression objection. Blane deposed that compliance would be “significant and onerous” given that the project ran for some four years, he worked on multiple projects with the builder, and he did not maintain separate electronic folders for each project.

He estimated that thousands of documents might fall within the subpoena’s scope.

Lundberg J was unimpressed. His Honour held that a subpoena recipient “is expected to have undertaken some good faith efforts to assess the compliance task, so as to then provide the [C]ourt with a more granular assessment of the work and cost involved”: at [47]. Blane’s evidence was, in his Honour’s view, “sparse in this regard, and little more than conjecture”.

The Court observed that examining one person’s email folder and phone memory for a particular project, even over four years, would not be overly onerous, particularly with appropriate search terms. The categories in the subpoena identified documents or classes of documents “with the necessary precision,” and the inclusive phrases such as “all records” had to be read in the context of the limiting descriptions that followed.

The spectre of third-party liability

Blane also raised the concern that the plaintiffs were using the subpoena to assess his potential liability to them. His Honour acknowledged this concern but held it was outweighed by the evident relevance of the material for the legitimate purpose of the arbitration. Any risk of improper use was further mitigated by the implied undertaking that would attach to the documents upon production.

Key takeaways

This decision offers several practical lessons:

1. The arbitration context does not immunise a subpoena from challenge, but the breadth of arbitral issues will inform the relevance inquiry. Where an arbitration involves wide-ranging disputes, a correspondingly broad subpoena may be justified.
2. Mere overlap with potential discovery does not defeat a subpoena. A party seeking to set aside a subpoena on this basis must point to an “additional vice” beyond the overlap itself.
3. Oppression requires evidence, not assertion. A subpoena recipient who claims compliance would be oppressive must demonstrate good faith efforts to assess the compliance task and provide the Court with granular evidence of the work and cost involved. Broad statements about complexity and volume will not suffice.
4. Deference to the arbitrator: Courts will accord a degree of deference to an arbitrator’s assessment that documents are relevant to the hearing and determination of the issues.
5. Costs risk: The provisional indication was that Blane would pay the costs of the unsuccessful application, reinforcing the risk for third parties who challenge subpoenas without adequate evidential support.