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AI hallucinations hit the High Court
- Jul 3, 2025
- Latest Journal
by Jamie Tomlinson, Imogen Jones, Lucy Grivvell & Matt Herrmann
www.dacbeachcroft.com
Overview
R. (on the application of Ayinde) v Haringey LBC and Al-Haroun v Qatar National Bank QPSC1
Generative Artificial Intelligence ("GenAI") continues to have a profound impact on the legal profession. While many practitioners are still getting to grips with the various new technologies which promise to improve efficiency, recent developments highlight the dangers of overreliance.
On 6 June 2025 the High Court handed down a judgment in respect of two cases referred to it under the "Hamid Jurisdiction" (a mechanism allowing the court to refer potential abuses of procedure to a "Hamid Judge" for consideration). The Court scrutinised the apparent misuse of GenAI by the parties' legal teams in both instances, reminding lawyers of their fundamental professional duty to take responsibility for their own submissions, including by taking steps to verify GenAI's output.
Ayinde v London Borough of Haringey
The first case2 concerned a dispute between Mr Ayinde and the London Borough of Haringey ("Haringey") arising out of Mr Ayinde's application for social housing assistance. Mr Ayinde had requested urgent interim accommodation, which was not granted, and subsequently brought judicial review proceedings against Haringey for its alleged breach of section 188(3) of the Housing Act 1996.
The barrister instructed by Mr Ayinde drafted grounds for the judicial review supported by (on their face) compelling authorities. Haringey's solicitors wrote to Mr Ayinde's team upon finding that five of the cases referred to in the grounds for judicial review appeared to not exist. Rather than simply providing the authorities, Mr Ayinde's barrister drafted what the Judge later called "a quite remarkable letter", criticising Haringey's focus on "errors in citations" which could, apparently, be "easily explained" (although no attempt to explain was forthcoming).
In reality, those five cases did not exist and Mr Ayinde's grounds misidentified the effect of relevant legislation. The matter was brought to the attention of the Court on the issue of wasted costs, and an order was duly granted in Haringey's favour. The Judge, in an excoriating judgment, said: "It is wholly improper to put fake cases in a pleading. It was unreasonable, when it was pointed out, to say that these fake cases were "minor citation errors" or to use the phrase of the solicitors, "Cosmetic errors". While he stopped short of finding that Mr Ayinde's solicitors or counsel had used GenAI to draft the grounds for judicial review and list of authorities, that inference is easily drawn. The Judge referred Mr Ayinde's barrister to the Bar Standards Board and his solicitors to the Solicitors Regulation Authority.
At the Hamid hearing, Mr Ayinde's barrister accepted that she had been negligent in citing fabricated case law but denied deliberately using GenAI to conduct legal research. She suggested that she had relied on a list of authorities when drafting Mr Ayinde's grounds (but did not explain how that list came to exist). She also accepted that she may have inadvertently relied on GenAI-generated responses to Google searches in her research. In light of those explanations, the
Court found the threshold for contempt of court proceedings to have been met: either the barrister had deliberately included fake citations, or she had covered up the full extent of her use of GenAI. While those proceedings were not ultimately initiated, (owing, in part, to the mitigating factor of counsel's relative inexperience), the Judge was anxious that the Court's leniency should not set a precedent, noting: "Lawyers who do not comply with their professional obligations in this respect risk severe sanction."
Al-Haroun v Qatar National Bank and QNB Capital
Mr Al-Haroun3 sought substantial damages for alleged breaches of a financing agreement. The defendants made applications to dispute the Court's jurisdiction and to strike out the claim. The Court granted the defendants an extension of time to file and serve evidence in relation to those applications. In response, the claimant made an application to have that order set aside. This application was supported by witness statements from Mr Al-Haroun and his solicitor.
The claimant's application was dismissed and referred for consideration by a Hamid Judge after the defendants found that both witness statements relied on authorities which were either fictitious, or, where they did exist, did not contain the passages ostensibly quoted from them.
At the Hamid hearing, the claimant admitted to having generated fake citations using publicly available GenAI tools. While the claimant's solicitor had not himself used GenAI to conduct the research, he had, by his own admission, relied on legal research produced by his own client, the claimant, without independently verifying the authorities. The Court found: "it is extraordinary that the lawyer was relying on the client for the accuracy of their legal research, rather than the other way around." The Court referred to the solicitor's behaviour as "a lamentable failure to comply with the basic requirement to check the accuracy of material that is put before the court." Accordingly, the solicitor was referred to the Solicitors Regulation Authority.
Analysis
These decisions are a stark reminder of the serious consequences of a failure to check-and-challenge GenAI output. The risks of overreliance on GenAI-generated output are numerous and significant (and for a more detailed analysis, see our previous article on AI in the arbitration context here. That is not to detract from the obvious benefits of legal GenAI tools, but while they continue to generate fabricated information (hallucinations), lawyers should exercise appropriate professional scepticism.
The Hamid Judge made a finding to that effect: "Those who use artificial intelligence to conduct legal research notwithstanding these risks have a professional duty therefore to check the accuracy of such research by reference to authoritative sources, before using it in the course of their professional work (to advise clients or before a court, for example)."
This is not new law. Rather, it is a reminder of existing principles which appear, in the age of GenAI, to have been quickly forgotten. Access to a tool which mimics a lawyer's output does not release its user from its duties not to mislead the court or to act in its clients' best interests. Lawyers need not wait for AI-specific regulation to tell them that.
References
[1] The King on the application of Frederick Ayinde v The London Borough of Haringey Hamad Al-Haroun v Qatar National Bank Qpsc, Qnb Capital Llc [2025] EWHC 1383 (Admin)
[2] R (on the application of) Frederick Ayinde v The London Borough of Haringey [2025] EWHC 1040 (Admin)
[3] Hamad Al-Haroun v Qatar National Bank QPSC and QNB Capital LLC