‘A serious failure’: CPS prosecutor cites imaginary case to high court after AI search

A senior crown prosecutor acting in a high court case cited an imaginary legal precedent in an error that has sparked fresh concerns about AI hallucinations infecting the justice system. Ravinder Dhillon, representing the Crown Prosecution Service (CPS), referenced an entirely made-up case during a dispute over whether a child should be prosecuted for the rape of his younger sister, court documents have revealed. Her explanation for how the nonexistent case came to be relied on has been called “unsatisfactory” by two senior high court judges and a “serious failure” by an expert in AI and law.

The Guardian understands the reference came from an AI response generated during an internet search. The case adds to dozens of others where AI-related errors have plagued court proceedings this year, mostly from people who are not legally qualified representing themselves, and often in employment tribunal cases. It is only the second known case involving the CPS – the main public agency bringing criminal prosecutions in England and Wales – which admitted in February that one of its lawyers acting in an extradition case involving two Romanians convicted of minor offences cited nonexistent legal authorities, likely caused by AI.

Those made-up cases were only spotted when opposition lawyers could find no trace of them and the CPS concluded “the risk of recurrence was low”. In the latest case, lawyers for the boy, who was 11 at the time of the alleged rape of his seven-year-old sister, were challenging the CPS’s decision to prosecute him. They alleged prosecutors had failed to take into account representations from social workers, youth workers and a forensic psychologist.

Dhillon, a senior crown prosecutor in the CPS’s rape and serious sexual offences unit, was arguing in favour of the prosecution of the child and submitted a detailed reference to a case she called CPS – R v J [2024] EWCA Crim 3529. It turned out not to exist. The decision to proceed was taken by Dhillon in April and confirmed by the chief crown prosecutor. Then in October Dhillon admitted that the nonexistent citation had been made in error.

She said she had been referring to a completely different decision – this time a real one – that was made 15 years earlier. “This was used as a legal source to argue for the prosecution of a child and that legal source doesn’t exist: that’s a serious failure,” said Brian Flanagan, associate professor of law at Maynooth University in Ireland who investigates the use of AI by judges. “It calls into question norms of trust in the law where we treat authorities as precious things.

You can’t make them up; it’s out of bounds. AI increases the risk that is going to happen because of the time you can save. It is not great for any professional to do this, but when the professional is working for the state it takes on a different aspect, because the power of the state is immense.” The high court said the CPS’s reference to a fictitious case did not affect the outcome of the boy’s challenge to the decision to continue with his prosecution, which is listed to go to trial in the youth courts later this week.

In June 2025, the high court responded to AI hallucinations in cases spanning housing to banking, by calling on the Bar Council and the Law Society to consider steps to curb the problem “as a matter of urgency”. Dame Victoria Sharp, then president of the King’s bench division, warned of “serious implications for the administration of justice and public confidence in the justice system if artificial intelligence is misused” and said lawyers misusing AI could face sanctions, from public admonishment to contempt of court proceedings and referral to the police.

Asked for comment, the CPS said it has a strict AI policy “which limits its use so that it is not used to make legal decisions and there must be human checks for accuracy”. A spokesperson said the CPS “identified an error had occurred from conducting legal research using the internet”. skip past newsletter promotion Free newsletter | Every day Sign up to Headlines UK Get the day’s headlines and highlights emailed direct to you every morning Enter your email Sign up after newsletter promotion “As soon as this error was identified, it was remedied and an internal review was carried out to establish how this had occurred and to check that no other cases have been affected,” they said.

“Following the rapid review we shared learnings, including that case law must be cited from trusted legal sources.” It is understood the internet search delivered an AI summary which contained the fictional case details. The latest incident brings to 101 the number of entries in a UK tracker maintained by Doughty Street Chambers barrister Matthew Lee covering confirmed, suspected and disputed AI-related errors, as well as related false citations.

He said the cases identified may be the “tip of the iceberg”, as many lower court decisions are never published. He added there are privacy and confidentiality risks associated with the CPS using AI, given the highly sensitive information it handles, and warned that AI was creating additional work for barristers, who need to spend time checking the authenticity of legal authorities appearing in case papers where AI may have been used in their preparation.

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