In March 2026, the Irish Court of Appeal provided its first guidance to lawyers and litigants on the use of generative AI in litigation in Guerin v O’Doherty  [2026] IECA 48. The decision concerned an appeal by the defendant, Gemma O’Doherty against the dismissal of her application to strike out a defamation claim.

The Court dismissed Ms O’Doherty’s appeal. In rejecting all eight grounds of appeal, the Court observed that much of Ms O’Doherty’s submissions and complaints addressed matters that either did not arise on the appeal, or were irrelevant to the question whether the court below had erred in refusing to strike out the proceedings (at paragraph 27).

Acting in person, Ms O’Doherty used AI to prepare her written submissions for the appeal. However, she did not notify the plaintiff’s solicitors in advance that she had done so. The Court found that Ms O’Doherty’s submissions contained a number of “hallucinated authorities” which did not exist, or which did not support the propositions they purported to establish. This caused the plaintiff’s solicitors to spend time and costs attempting to locate non-existent authorities.

The Court emphasised that all parties, whether represented or not, have an obligation not to mislead the court. This includes the obligation not to rely on or advance submissions based on authorities that have no basis in law. The Court also noted that lawyers are subject to professional and ethical obligations which do not apply to litigants in person, but did not address those obligations as they did not arise in the case.

To assist parties, the Irish Court of Appeal set out the following general guidance for parties, whether acting through counsel or in person:

1. Parties are entitled to use AI to assist in carrying out research in respect of their case provided they do so responsibly and do not, even inadvertently, mislead the court by advancing propositions or relying upon supposed authorities which have no foundation.
2. In all cases where they do so, they should expressly inform both the other parties and the court of their use of AI.
3. A self-represented party is as equally responsible for the ultimate written or oral work as lawyers.
4. It is important, therefore, that any party who uses AI as part of their research independently verifies the accuracy of their submissions and the authorities cited as supposedly establishing the propositions advanced.
5. No authority should be cited by a party who has not verified that it is a genuine judgment of the court and that it is, or at least arguably is, authority for the proposition contended for.

The Court had strong words of caution against the improper use of AI, noting that it could lead to wasted time and costs, cast an unfair burden on the opposing party, potentially bring the administration of justice into disrepute, and mislead the court. The Court emphasised that it had a variety of sanctions at its disposal in cases where parties use AI in breach of these guidelines and where such improper use has the potential to mislead the court.

Fortunately for Ms O’Doherty, the Court declined to draw any adverse conclusions against her on that occasion, reasoning that at the time submissions were filed, no guidance was available to litigants in relation to their obligations to the other parties and to the court as regards the use of AI-generated material in proceedings.

What it does mean is that going forward, all litigants and lawyers appearing before the Irish courts will have to ensure that they abide by the guidance set out above, or risk adverse inferences and sanctions.

Closer to home, at least two published decisions of the Cayman Islands courts have addressed the improper use of AI in litigation involving litigants in person (see our previous blog: Cayman Court issues warning on AI use in legal filings). Given the courts’ warnings, lawyers can have no excuse.

In other jurisdictions, there have, unfortunately, been several cases of lawyers being found to have used generative AI improperly, resulting in not only professional embarrassment but also personal costs orders. For instance, in Singapore, the improper use of generative AI recently resulted in the imposition of a personal costs order of S$800 against a lawyer who blamed his junior for the use of AI: see Tajudin bin Gulam Rasul v Suriaya bte Haja Mohideen  [2025] SGHCR 33.

By now, lawyers ought to be keenly aware of the limitations and common pitfalls of AI. When in doubt, and even when not in doubt, always challenge the AI.

Disclaimer

Harneys does not practise the laws of Ireland and this blog post is not intended as legal advice in respect of Irish law. However, the guidance from the Irish Court of Appeal is instructive for practitioners across all jurisdictions, including the offshore jurisdictions in which Harneys operates, where courts have similarly cautioned against the improper use of generative AI in litigation.