Legal Professional Content | 5 min
December 16, 2025 ・ 5 min read
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This appeal arose from the first-instance decision of Mertz & Mertz (No 4) [2025] FedCFamC1F 400. The appellant appealed the final orders, but ultimately discontinued the proceedings two days before the hearing of the appeal was listed.
After the discontinuance, the only remaining issue for determination was the issue of costs. However, the matter became notable because of concerns about the accuracy and integrity of the documents filed on the appellant’s behalf, specifically, the Summary of Argument and the List of Authorities.
When the Full Court (comprised of Aldridge, Carew and Behrens JJ) examined the appellant’s written materials, it identified that:
Several cited authorities did not exist; and
The documents had the appearance of being generated by AI and included 'inaccurate and misleading references to case law' [4].
Importantly, the documents had been settled by Senior Counsel, Junior Counsel, and the solicitor acting, yet the errors were not detected by any of them before filing.
The Full Court stressed that while drafting tools (including AI) can be useful, they never displace the human lawyer’s professional responsibility to ensure accuracy. This dovetails with the principle repeatedly emphasised in Australian case law: lawyers owe an overriding duty to the Court not to mislead, whether deliberately or inadvertently.
In Helmold & Mariya (No 2) [2025] FedCFamC1A 163, the Full Court (comprised of Christie, Campton and Aldridge JJ) similarly warned against the careless submission of material generated using automated tools. The judgment underscored that the convenience of technology can become a liability if practitioners fail to perform the necessary critical evaluation of what is produced in their name. Technology can assist, but it cannot replace professional judgment and verification.
Likewise, in Dayal [2024] FedCFamC2F 1166, the Court criticised the presentation of legally unsound or unverified material and described such conduct as falling below expected professional standards. The Court made clear that tools that “assist” cannot excuse a failure to check accuracy, confirm authority or correct errors.
Together, these cases form a trilogy of reminders that lawyers remain ultimately accountable, regardless of whether the initial text is generated by a junior lawyer, a template or generative AI.
The appeal was discontinued by the appellant.
The Full Court ordered the appellant to pay the respondent’s costs, fixed in the sum of $36,955. The Court also made an order, by consent, that the solicitor pay the respondent the sum of $10,000 towards the costs thrown away in dealing with the AI issue.
The Full Court directed that the practitioners involved be referred to the relevant professional regulatory bodies (The South Australian Legal Profession Conduct Commission and the Victorian Legal Services Board and Commissioner), given the seriousness of submitting documents containing non-existent authorities.
Mertz & Mertz (No 3) is not a case about condemning AI. It is a case about professional responsibility in an AI-enabled legal environment.
The Full Court’s message aligns with what was said in Helmold & Mariya and Dayal:
AI is valuable, but only when paired with a lawyer’s skill, judgment and verification.
Generative AI can:
Speed up legal drafting;
Locate relevant authorities faster;
Improve structure and clarity of submissions; and
Reduce administrative burden when it is used wisely.
The problem in this case was not the use of AI itself. It was the failure to verify AI-assisted outputs, even after three different practitioners endorsed them.
For firms using sophisticated tools, such as LEAP’s Matter AI and LawY, this case demonstrates the following principle in practice:
AI is a powerful partner in legal work. Lawyers unlock its full potential when they combine its efficiency with their own expertise, scrutiny and ethical judgment.
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On 23 July 2025 in Shinohara & Shinohara [2025] FedCFamC1A 126 (“Shinohara”), the Full Court put an end to the long-established family law practice of notionally ‘adding back’ to the asset pool, at step 1, property that no longer exists. While in Bevan [2013] FamCAFC 116, the Full Court questioned the use of addbacks, differently constituted Full Courts have since consistently authorised the use of addbacks as a legitimate pathway to calculate a just an equitable property settlement order. So, what does this mean for everyday practice?
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Whether you're starting work this new year at home or in the office, there are a number of tasks we recommend checking off your to do list to set yourself up for a productive and rewarding year in practice.
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The LEAP forms blog is now conveniently located in the LEAP Help Centre. Clients can stay up to date with LEAP Matters, forms and automated templates all through the searchable LEAP Help Centre. Clients can read about the latest changes to matter types and legal forms, but also find step-by-step guides, new feature announcements, user forums and a comprehensive library of resources, all in one place.
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LEAP users can now take advantage of LEAP's integration with InfoTrack's Will Register. Complimentary for all LEAP users, the Will Register makes it easier to navigate wills and probate matters. Accessible directly from the LEAP Marketplace, the Will Register allows you to sync selected LEAP matters to the registry. Information synced to the registry includes your client's details such as their name and date of birth as well as any wills you hold for them. The register, however, does not hold copies of wills or any testamentary documents to ensure the privacy of your client.
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