April 2026 Practical Guide By Mark Stanarevic

The Problem of Anonymous Online Defamation

Anonymous defamation is one of the fastest-growing categories of reputational harm in Australia. Fake Google reviews posted under pseudonyms, damaging social media posts from fabricated accounts, and malicious emails sent from disposable Gmail addresses can inflict serious financial and personal damage — and the victim often has no idea who is behind the attack.

The anonymity of the internet does not, however, provide immunity from the law. Australian courts have developed a robust procedural framework for preliminary discovery that enables prospective plaintiffs to compel technology companies, internet service providers, and social media platforms to disclose the identifying information of anonymous users. This article explains how that process works in practice.

What Is Preliminary Discovery?

Preliminary discovery is a court process that allows a person who intends to commence legal proceedings to obtain information about the identity or whereabouts of a prospective defendant before filing the substantive claim. In the context of anonymous online defamation, it is the primary mechanism for unmasking the person behind a pseudonymous post.

In the Federal Court of Australia, the power to order preliminary discovery is found in rule 7.22 of the Federal Court Rules 2011 (Cth). Each state and territory has its own equivalent provision. In Victoria, for example, the relevant rule is Reg 32.05 of the Supreme Court (General Civil Procedure) Rules 2015 (Vic).

The court must be satisfied of three matters before making an order:

  1. The applicant may have a right to obtain relief against the prospective respondent (i.e. a reasonable basis for a defamation claim);
  2. The applicant has made reasonable inquiries but is unable to ascertain the identity of the prospective respondent; and
  3. A third party (such as Google, Meta, or an internet service provider) knows or is likely to know the prospective respondent's identity, or has or is likely to have control of a document that would help ascertain it.

If those conditions are met, the court can order the third party to produce documents revealing the anonymous user's identity — typically IP addresses, email addresses, phone numbers, and account registration details.

How It Works in Practice: Two Instructive Cases

The Disgruntled Student: Musicki v de Tonnerre

In Musicki v de Tonnerre [2023] FCA 222, Dr Korana Musicki, a specialist vascular and endovascular surgeon, was the subject of a damaging Google review posted under the pseudonym "Dave Cross". The review stated: "terrible experience, was super keen to get me onto the table but then impossible to get ahold of for follow up, vague about incurred expenses, ended up with a massive bill."

Dr Musicki repeatedly asked Google to remove the review and to disclose the identity of the poster. Google refused on both counts. Dr Musicki then brought a preliminary discovery application in the Federal Court, which successfully compelled Google to produce identifying information associated with the account. The information revealed that "Dave Cross" was a pseudonym used by a disgruntled former student Dr Musicki had supervised.

Dr Musicki subsequently commenced defamation proceedings and obtained judgment for $75,000 in damages, plus legal costs.

The Rival Surgeon: Colagrande v Kim

In Colagrande v Kim [2022] FCA 409, Dr Colagrande, a cosmetic surgeon, was the subject of an anonymous review on the RateMD platform that referenced a criminal conviction — without mentioning that the conviction had been quashed on appeal.

After RateMD refused to remove the post, Dr Colagrande obtained a subpoena compelling RateMD to disclose the IP address of the reviewer. He then brought a separate preliminary discovery application against Telstra (Colagrande v Telstra Corporation Ltd [2020] FCA 1595) to identify the subscriber associated with that IP address. The trail led to a rival cosmetic surgeon and his wife.

The rivals were ultimately ordered to pay more than $450,000 in damages, plus costs and interest. This case illustrates that the process may require multiple steps — first identifying the IP address from the platform, then tracing the IP address to a subscriber through the internet service provider — but the courts have consistently facilitated this process where the underlying claim has substance.

Serving on Overseas Companies: Google, Meta, and Others

A common practical challenge is that the platform holding the identifying information is based overseas — typically in the United States. In Kabbabe v Google LLC [2020] FCA 126, the Federal Court considered an application by a Melbourne dentist to serve an originating application for preliminary discovery on Google in California.

Murphy J granted leave to serve Google by post in the United States, holding that the Federal Court had jurisdiction because the defamatory Google review was published in Australia (being the place where the review was downloaded and read), even if the review was posted from outside Australia. The same principle applies to content on Facebook, Instagram, X (formerly Twitter), and other global platforms.

This means that even where the platform operator is based offshore, Australian courts can and routinely do exercise jurisdiction to order disclosure of the anonymous user's identity. The standard filing fee for a Federal Court preliminary discovery application is approximately $815, though total legal costs will depend on the complexity of the matter and whether the application is contested.

Section 23A: New Privacy Safeguards

The Stage 2 uniform defamation law reforms introduced a new section 23A into the Defamation Act 2005 (enacted in Victoria through the Justice Legislation Amendment (Integrity, Defamation and Other Matters) Bill 2024). This provision requires courts to have regard to "privacy, safety or other public interest considerations" when deciding whether to grant preliminary discovery orders in defamation proceedings.

Section 23A provides for two categories of discovery:

  1. Identity discovery: orders to assist in identifying the person who published the defamatory material; and
  2. Contact discovery: orders to assist in locating a physical or digital address for the publisher, which is necessary for the service of a concerns notice — a mandatory prerequisite before commencing defamation proceedings.

The provision is principally aimed at preventing abuse of the preliminary discovery process — for example, by perpetrators of domestic violence seeking to unmask victims, or by powerful parties seeking to intimidate whistleblowers. In the majority of commercial and professional defamation cases, section 23A is unlikely to present a barrier. As the Law Council of Australia has observed, courts already possessed broad discretionary power to refuse discovery in inappropriate cases, and section 23A functions more as a guiding framework than a decisive rule of law.

That said, applicants should be prepared to address the court on why the privacy interests of the anonymous poster are outweighed by the applicant's legitimate interest in pursuing a defamation claim. This is particularly relevant where the anonymous material may constitute protected whistleblowing or political communication.

Step-by-Step: The Unmasking Process

The practical steps for identifying an anonymous defamer in Australia typically follow this sequence:

  1. Preserve the evidence. Take screenshots with timestamps, download cached versions, and record URLs. Anonymous content can be deleted at any time, and platform data retention policies mean that identifying information may not be stored indefinitely.
  2. Request removal and identity disclosure from the platform. Before approaching the court, you should make reasonable inquiries directly with the platform. Most platforms will not voluntarily disclose user identities, but making the request is necessary to satisfy the court that reasonable inquiries have been made.
  3. Assess the merits of the defamation claim. The court must be satisfied that you may have a right to obtain relief. This does not require proving your case in full, but you must demonstrate a reasonable basis for the claim — including that the material is defamatory, identifies you, and has caused or is likely to cause serious harm to your reputation.
  4. File a preliminary discovery application. In the Federal Court, this is made by originating application under rule 7.22 of the Federal Court Rules 2011. The application is supported by an affidavit setting out the defamatory material, the inquiries already made, and the basis for believing the third party (e.g. Google) holds identifying information.
  5. Obtain and serve the order. If the court is satisfied, it will order the platform or ISP to produce documents identifying the anonymous user. This typically includes email addresses, phone numbers, IP addresses, and account creation details.
  6. Trace the IP address (if necessary). If the platform can only provide an IP address, a second application may be needed against the internet service provider (Telstra, Optus, etc.) to identify the subscriber associated with that address.
  7. Issue a concerns notice. Once the defamer is identified, you must serve a concerns notice before commencing proceedings — a mandatory step under the uniform defamation legislation. This is where the contact discovery limb of section 23A is particularly useful.
  8. Commence defamation proceedings. If the matter is not resolved at the concerns notice stage, formal proceedings can then be filed.

Key Considerations Before Applying

Preliminary discovery is a powerful tool, but it is not appropriate in every case. Before proceeding, consider the following:

  • Strength of the underlying claim. The court will assess whether there is a reasonable basis for defamation proceedings. If the material is arguably true, or is clearly opinion rather than fact, the application may fail.
  • Serious harm. For publications after 1 July 2021, the applicant must demonstrate that the material has caused or is likely to cause serious harm to reputation. A single anonymous review seen by very few people may not meet this threshold.
  • Data retention. Platform operators do not retain identifying data indefinitely. Prompt action is essential. If months or years have passed since publication, the relevant records may no longer exist.
  • Costs. While the Federal Court filing fee is modest ($815), legal costs for the application, service on overseas entities, and any contested hearings will add up. In straightforward cases, total costs for the preliminary discovery stage are typically in the range of $10,000 to $30,000. Multi-step processes (e.g. platform to ISP to subscriber) will be at the higher end.
  • The Streisand effect. Pursuing legal action can sometimes draw more attention to the defamatory material. A strategic assessment of reputational risk is important before proceeding.
  • Alternative remedies. In some cases, content removal through the platform's internal processes, or through the eSafety Commissioner's Adult Cyber Abuse Scheme, may be more effective than identifying and suing the anonymous poster.

Can You Also Sue the Platform?

A related question is whether the platform itself — Google, Facebook, or a review site — can be held liable for hosting the anonymous defamation. Following the High Court's decision in Fairfax Media Publications Pty Ltd v Voller [2021] HCA 27, platform operators may be treated as publishers of third-party defamatory content in certain circumstances.

However, the Stage 2 reforms introduced section 31A, which provides a new defence for digital intermediaries — including social media platforms and review sites — where they were not aware of the defamatory nature of the content and took reasonable steps in response to a complaint. The availability of this defence depends heavily on whether and how the platform was notified, and the steps it took in response.

Where a platform has been notified of defamatory content and has failed to act, it may still face direct liability as a publisher. This is an important consideration when dealing with defamatory Google reviews or social media posts.

How Matrix Legal Can Help

Identifying anonymous online defamers requires a combination of legal expertise, forensic awareness, and strategic judgment. The process is time-sensitive — delay can result in the loss of critical identifying data — and must be calibrated to the strength of the underlying claim and the likely costs of recovery.

Mark Stanarevic and the Matrix Legal team advise on all aspects of anonymous defamation, including evidence preservation, preliminary discovery applications in the Federal Court and state Supreme Courts, service on overseas technology companies, and the strategic assessment of when to pursue identification versus content removal. If you are the target of anonymous online defamation, request a free assessment or call 1800 950 627.

This article is general information and not legal advice. Defamation risk turns on the precise words used, the publication context, the audience, and available evidence.