Apparent Obligation On Litigation Parties To Disclose Use Of AI Following Court Of Appeal Decision

In the recent decision in Guerin v Doherty [2026] IECA 48, the President of the Court of Appeal, Ms. Justice Costello, set out new guidelines on the use of AI in legal proceedings. The provision of Judicial guidance in this area is to be welcomed.

Whilst the guidelines in most respects mirror previous guidance from the legal professional bodies, certain of the guidelines in some respects they go beyond equivalent provisions in that professional guidance and in other jurisdictions.

Specifically, Costello P appears to have introduced an obligation on parties to disclose to the other parties and to the Court in the event that they use AI for research during the proceedings. This would be quite a significant development.

The full background is as follows.

Hallucinations and Fictitious Authorities

In Guerin v Doherty, the Defendant/Appellant used AI to prepare written submissions, which were filed in support of her appeal. The Appellant did not however verify the existence of the cases cited or confirm whether the authorities relied upon supported her arguments. Counsel for the Plaintiff/Respondent informed the Court that they searched extensively for the non-existent authorities, and this unnecessarily added to the Respondent's workload and costs. The Court noted that lawyers are subject to professional and ethical obligations which extends to the use of AI when practicing their profession. The Court highlighted that it has a variety of sanctions open to it where parties are in breach of AI guidelines but decided not to make any adverse conclusion against the Appellant in this instance. Costello P did however decide to provide assistance for litigants in terms of use of AI in future cases.

New Guidelines

In this regard Costello P set out the following guidelines for the use of AI in legal proceedings:

• Duty not to mislead the court: Parties are entitled to use AI in carrying out research provided they do so responsibly and do not mislead the Court by advancing propositions that have no legal foundation.
• Disclosing the use of AI:In all cases where parties use AI to carry out such research, they should expressly disclose this to the other parties and to the Court.
• Lay litigants: A self-represented party is responsible for oral or written submissions as much as the lawyers representing the parties.
• Rigorous verification: There is an onus on any party who uses AI as part of their research to verify the accuracy of the authorities cited and propositions advanced.
• Unverified Citations & Authorities: No authority should be cited by a party who has not verified that it is a genuine judgment of the Court that is an authority for the proposition contended.

Comparison to Other Jurisdictions

Similarities in Approach

Consistent with the Irish position, legal practitioners in England & Wales have an obligation to verify the accuracy of the authorities they intend to rely upon. There is an onus on legal practitioners to implement practical and effective measures to regulate the provision of legal services and ensure that every individual providing legal services complies with their professional and ethical duties when using AI.

The Supreme Court of Victoria (Australia) set out its own guidelines on the use of AI in legal proceedings that aim to promote a thorough verification process, a prudent approach when uploading confidential information to AI platforms and ensuring that the submissions advanced have a proper legal basis.

Disclosing the Use of AI

It seems the biggest difference between Ireland and other jurisdictions is the apparent requirement for legal practitioners to disclose the use of AI.

In this regard Costello P stated:-

"...Parties are entitled to use AI to assist in carrying out research in respect of their case .... In all cases where they do so, they should expressly inform both the other parties and the court of their use of AI in this regard".

This appears to mean that both legal practitioners and lay litigants must expressly disclose the use of AI where they use same "...in carrying out research in respect of their case". The Judgment was in the context of the use of AI for the purposes of Legal Submissions filed in Court, and perhaps it was intended to confine the obligation to such use, but taken literally the guidelines go considerably further and create a disclosure obligation where there is any use of AI in carrying out research during the currency of the litigation.

In England & Wales no such disclosure obligation exists at present, while in Victoria, Australia the guidance suggests that parties must not indirectly mislead another party but need only expressly disclose the use of AI "..where appropriate (for example, where it is necessary to enable a proper understanding of the provenance of a document or the weight that can be placed upon its contents)". The same guidelines however go further in terms of lay-litigants who use AI, stating they should "..identify this by including a statement as to the AI tool used in the document that is to be filed or the report that is prepared...". There is a certain logic to the approach taken in Victoria given that legal practitioners already have a duty not to mislead the Court whereas lay litigants have no such obligations.

Conclusion

In Ireland, legal practitioners are also subject to professional and ethical conduct guidelines which includes an obligation not to mislead the Court. Moreover the legal profession has also produced guidelines for the use of AI by practitioners. Yet, in light of these new guidelines, there now appears to be an additional onus on legal practitioners (as well as lay litigants) to expressly disclose the use of AI research to other parties and the Court.

It will be interesting to see how strictly the legal professions interpret these guidelines and how Irish practice evolves generally.

1. See the Law Society's Guidelines for the use of generative artificial intelligence, February 2026at: https://www.lawsociety.ie/artificial-intelligence-ai/generative-ai-guidance/
2. Guerin v O'Doherty [2026] IECA 48 (Unreported, Court of Appeal, 26 March 2026).
3. R (on the application of Ayinde) v London Borough of Haringey [2025] EWHC 1383.
4. Supreme Court of Victoria, 'Guidelines for Litigants: Responsible Use of Artificial Intelligence in Litigation' (May 2024) https://www.supremecourt.vic.gov.au/forms-fees-and-services/forms-templates-and-guidelines/guideline-responsible-use-of-ai-in-litigation accessed [21 April 2026].
5. Ibid.
6. Law Society of Ireland, Guide to Good Professional Conduct for Solicitors (4th edn, Law Society of Ireland 2022), p5.
7. For example the aforementioned Law Society's Guidelines for the use of generative artificial intelligence, February 2026 at: https://www.lawsociety.ie/artificial-intelligence-ai/generative-ai-guidance/

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