Apparent AI Hallucinations in Briefing From Both Parties

That's a new one on me, from a UK trademark appeal; the plaintiff, who was self-represented, admitted to using generative AI, and the defendant's lawyer was strongly suspected of so doing:

8. At the start of the hearing, I asked Dr Soufian if he had drafted the documents and he said he had drafted it with the assistance of Chat GPT. I pointed out the numerous errors in the citations and problems with the skeleton and he politely apologised and did so unreservedly. Before moving on, it is worth noting that most of the skeleton produced by Chat GPT was made up of arguments purportedly relating to the evidence in the case. However, the factual issues highlighted were largely not relevant to the issues before me and the proposed arguments were not very helpful. In other words, even aside from the fabricated citations, the output of Chat GPT was in fact unhelpful to him.

9. In the case of Mr Caddy, who is a trade mark attorney, his skeleton argument dated 6 June 2025 included three cases which existed and were correctly cited. But it was unclear to me the cases cited stand for the propositions claimed by Mr Caddy.

10. During the Hearing, I asked Mr Caddy to identify the part of the judgments which supported the propositions made. He said, "I cannot actually remember that now, to be honest with you". I gave him time to read the judgments so as to find the relevant paragraphs. He could not do so. He then said he got the references from a "previous edition of Kerly's Law on Trade Marks". I could not find any support for the propositions (or anything similar) in Kerly during the hearing. He then said he could not remember where he got them from, saying maybe it was Wadlow [on the Law of Passing Off] but said he went on to say that did not make much sense. After the hearing, I checked Wadlow and could not find anything matching the propositions.

11. A few hours after the hearing, Mr Caddy sent an email to the Secretariat, he said in the email that he had not been expecting to "make out my own side's case more so than had been done in the skeleton". He then went on to try and show support for the propositions in the three cases cited in the skeleton. In my view, nothing in the email improved Mr Caddy's position and the quotation above clearly makes it worse….

30. I cannot say how Mr Caddy came up with the propositions of law he put forward for the three cases. I emphasise once more that a fabricated citation is not just an entirely made up case, but also includes citing a case for a proposition where there is absolutely no basis in the case for that proposition to be made. As I have already mentioned, even after his clarification I struggle to see how the cases he cites support his propositions more than in the most general and abstract sense.

31. Three things about Mr Caddy's conduct concern me greatly. First, he did not know when asked in the hearing where he obtained the propositions of law he included in a skeleton argument, even though the document was dated less than a week before the hearing. Secondly, he appears to think that he is not expected to be ready to expand on points made in his own skeleton argument at the hearing. Thirdly, he appears to think it is acceptable to use out-of-date textbooks. It is necessary for all lawyers to have access to relevant and up-to-date textbooks and relevant case reports whether online or printed and whether within their own firm or using one of the law libraries available to them, which for those who are London-based (like Mr Caddy) include the Intellectual Property Reading Room at the British Library.

32. In the end, I have decided I will not refer Mr Caddy to IPREG on this occasion. I accept that it is possible that he found these references and simply read them (misunderstood them) in a way I cannot follow or understand. However, even if this is the case he needs to seriously reflect on how he conducts his practice in the future, including how he undertakes legal research, how he drafts skeleton arguments, and he must ensure that when he appears before a tribunal he is properly prepared to do so. Advocates should always be prepared to explain to a court or tribunal what they have included in skeleton or other written arguments.

Check out Damien Charlotin's AI Hallucination Cases database, which is now at 210 cases (more than half from the U.S.), as well as Peter Henderson's AI Law Tracker, now at 223 cases.