UK law firm Pinsent Masons reprimanded by court over AI error

Top UK law firm Pinsent Masons has been admonished by London’s High Court after its lawyers made false submissions to a judge based on AI, the latest high-profile mistake resulting from the industry’s increasing use of the technology. Pinsent Masons misled the court twice by inaccurately citing a statute in relation to a routine insolvency application, an error that was only picked up when the judge queried the reference. Judge Mark Mullen said in his ruling that work pressure did not excuse a “failure to check the accuracy of the material”.

The submissions were made by a junior lawyer, referred to as “LA” in Mullen’s judgment, with oversight from a senior associate and partner. In their witness statements, the supervisors said that they were not aware that the junior lawyer had used AI. The case is the latest reprimand of a large law firm for AI-generated errors, as the industry tries to get to grips with the technology. Pinsent Masons apologised and referred itself to the Solicitors Regulation Authority, which regulates solicitors in England and Wales. Mullen’s judgment set out conversations between “LA” and the AI tool, which were submitted to the court by the firm.

The transcript included a warning from the AI bot that it was “not fully confident” it was reproducing the exact statutory wording, advising the lawyer to verify it before submitting it to a court. “The administration of justice cannot properly function if the court cannot trust its officers . . . to protect it from being misled,” Mullen said in his judgment handed down last week.  He added: “Legal professionals bear ultimate responsibility for their work and cannot outsource the process of legal research or of legal reasoning to an AI. It is a tool to be used with caution. AI has the potential to be wholly unreliable.” Law firm Sullivan & Cromwell told a US federal bankruptcy court last month that a major filing it made in a high-profile case contained multiple AI “hallucinations”. London’s High Court last year handed down a judgment citing two separate cases containing false information in which barristers had used, or were suspected of using, AI.

In one case, as many as 18 fake case citations were used. Pinsent Masons, whose equity partners were paid an average £797,000 last year, said: “We have apologised unreservedly to the court and are taking steps to strengthen our processes and oversight to ensure this does not happen again.” The firm told the court that it was piloting a new AI program and had taken other steps “to put safeguards on its use”. Mullen said that given the firm had made a self-referral to the SRA and borne the costs to the client, it was not necessary to initiate contempt of court proceedings. The SRA said: “We are aware of the report that Pinsent Masons have made, and we are looking into it before deciding on any potential next steps.”