Pinsent Masons slammed by judge over junior lawyer’s AI blunder

Cited law that didn’t exist

Pinsent Masons has been criticised by a High Court judge after AI-hallucinated legal authorities, produced during a junior lawyer’s research, were relied upon during insolvency proceedings.

According to the judgment, the firm cited an insolvency rule that did not exist, which arose from a junior solicitor using AI tools to conduct legal research for the proceedings.

The incident revolved around a “bulk transfer” insolvency application. Broadly speaking, this mechanism allows for the simultaneous transfer of open insolvency cases from one insolvency practitioner to another.

During the proceedings, Pinsent Masons, acting for the applicants, wrote to the court citing an insolvency rule (and quoting supporting statutes) which it claimed gave the court power to release outgoing liquidators from liability.

After the judge queried the original letter, the firm doubled down and sent a second letter explaining that the wording was a “summary conclusion” drawn from multiple rules.

However, the judge stated that this explanation was “impossible to accept”, saying he was “astonished” by the response. Citing inconsistencies in the letter, he added:

“[The first letter] had caused me to be concerned that a cavalier attitude was being taken as to the accuracy of the material that Pinsent Masons were putting before the court. As I say, it struck me as likely to be an AI hallucination, which had not been checked. The attempt to explain it away in what appeared to be an untruthful manner in the 14th April Letter only heightened my concerns.”

According to the ruling, the junior lawyer was repeatedly warned by the tool to verify the material and check it against authoritative legal sources. The second letter was also found to be prepared with AI.

The judgment contains extensive records of internal AI chat history. For instance, the junior lawyer appeared to have asked the AI tool what the Insolvency Act said, rather than checking the legislation themselves, a point which the judge found “concerning”.

The judge also criticised the failure of supervisors (despite not being aware of the use of AI) to properly check the work done and that there appeared to be a “failure to supervise [the junior lawyer] adequately”.

The firm has since self-referred to the Solicitors Regulatory Authority (SRA).

In a statement to Legal Cheek, Pinsent Masons 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. As the matter has been before the Court, it would not be appropriate to comment further.”