British prosecutor cited an imaginary case found through an AI search in the High Court, in what an expert called a ‘serious failure’

A senior crown prosecutor acting in a High Court case in England cited an imaginary legal precedent, court documents have revealed. The reference is understood to have come from an AI response generated during an internet search, sparking fresh concerns about AI hallucinations infecting the justice system.

Ravinder Dhillon, representing the Crown Prosecution Service (CPS), referenced the entirely made-up case during a dispute over whether a child should be prosecuted for the rape of his younger sister. She submitted a detailed reference to a case she called CPS – R v J [2024] EWCA Crim 3529. It turned out not to exist.

The boy was 11 at the time of the alleged rape of his seven-year-old sister. His lawyers were challenging the CPS decision to prosecute him, alleging 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 rape and serious sexual offences unit, was arguing in favour of the prosecution. The decision to proceed was taken by her in April and confirmed by the chief crown prosecutor. Then, in October, she admitted the nonexistent citation had been made in error, saying she had been referring to a completely different, real decision made 15 years earlier.

It is understood the reference came from an AI summary delivered by an internet search, which contained the fictional case details.

Brian Flanagan, associate professor of law at Maynooth University in Ireland, who investigates the use of AI by judges, called it a “serious failure”. He said a legal source that does not exist had been used to argue for the prosecution of a child, calling into question norms of trust in the law, where authorities are treated as precious and cannot be made up.

Flanagan added that it is not great for any professional to do this, but that when the professional is working for the state it takes on a different aspect, because the power of the state is immense. AI increases the risk because of the time it can save, he said.

The High Court said the CPS 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.

It is only the second known case involving the CPS. In February the service admitted that one of its lawyers, acting in an extradition case involving two Romanians convicted of minor offences, had cited nonexistent legal authorities, likely caused by AI. Those made-up cases were spotted only when opposition lawyers could find no trace of them, and the CPS concluded the risk of recurrence was low.

The case adds to dozens of others where AI-related errors have plagued court proceedings this year, mostly involving people who are not legally qualified representing themselves, and often in employment tribunal cases.

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 if artificial intelligence is misused, and said lawyers misusing AI could face sanctions ranging 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 had identified that an error had occurred from conducting legal research using the internet.

The spokesperson added that as soon as the error was identified, it was remedied and an internal review was carried out to establish how it had occurred and to check that no other cases had been affected. Following the review, learnings were shared, including that case law must be cited from trusted legal sources.

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 and related false citations. He said the cases identified may be the tip of the iceberg, as many lower court decisions are never published. He also pointed to privacy and confidentiality risks, and to the additional work created for barristers who must check the authenticity of legal authorities in case papers where AI may have been used.