A senior Crown Prosecution Service prosecutor cited a legal case that does not exist while arguing in a High Court dispute over whether a child should be prosecuted, court documents have revealed. Two senior High Court judges called her explanation for how the nonexistent case came to be relied on "unsatisfactory", and Brian Flanagan, an associate professor of law at Maynooth University who investigates judges' use of AI, called it a "serious failure". The Guardian understands the reference came from an AI response generated during an internet search.
Ravinder Dhillon, a senior crown prosecutor in the CPS's rape and serious sexual offences unit, submitted a detailed reference to a case she called CPS - R v J [2024] EWCA Crim 3529 while arguing in favour of prosecuting the child. The citation turned out not to exist. Lawyers for the child were challenging the CPS's decision to prosecute, alleging prosecutors had failed to take into account representations from social workers, youth workers and a forensic psychologist.
The decision to proceed was taken by Dhillon in April and confirmed by the chief crown prosecutor. In October, Dhillon admitted the nonexistent citation had been made in error, saying she had been referring to a completely different decision, this time a real one, made 15 years earlier.
The CPS is the main public agency bringing criminal prosecutions in England and Wales. It admitted in February 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 only spotted when opposition lawyers could find no trace of them, and the CPS concluded that "the risk of recurrence was low". 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".
Flanagan said the use of a fabricated authority in a prosecution argument raised wider questions. "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," he said. "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 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", adding: "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. 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 that contained the fictional case details.
The High Court said the CPS's reference to a fictitious case did not affect the outcome of the child's challenge to the decision to continue with the prosecution.
The episode 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 that 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.
Dame Victoria Sharp, then president of the King's bench division, warned at the time of the June 2025 response 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 ranging from public admonishment to contempt of court proceedings and referral to the police.
Analysis
Why This Matters
- The case puts a state prosecuting authority, not a self-represented litigant, at the centre of the AI hallucination problem in courts, and the CPS has now acknowledged two such episodes.
- It raises the question of how fabricated authorities are caught: in both CPS cases the invented citations surfaced only because opposing lawyers could not find them.
- The boy's challenge failed to stop his prosecution, and the case is listed for trial in the youth courts later this week.
Background
AI tools that summarise search results or draft legal text can produce plausible-looking citations to cases that were never decided, a failure widely described as hallucination. Courts in England and Wales have been grappling with the consequences, and the High Court has already asked the professional bodies for barristers and solicitors to consider how to curb the problem. The CPS is the public body that brings criminal prosecutions in England and Wales and handles highly sensitive material, making its use of such tools a particular concern for practitioners.
Key Perspectives
Brian Flanagan, Maynooth University: says using a nonexistent legal source to argue for a child's prosecution is a "serious failure" that calls into question trust in legal authorities, and that the risk takes on a different aspect when the professional works for the state.
The Crown Prosecution Service: says its AI policy bars use of the tools for legal decisions and requires human accuracy checks, that the error came from legal research using the internet, and that it was remedied with an internal review and lessons shared on citing case law from trusted sources.
Two senior High Court judges: called the prosecutor's explanation for how the nonexistent case came to be relied on "unsatisfactory".
Matthew Lee, Doughty Street Chambers: says the cases in his tracker may be the "tip of the iceberg" and warns of privacy and confidentiality risks in CPS use of AI and extra checking work for barristers.
Dame Victoria Sharp: warned of serious implications for the administration of justice and public confidence if AI is misused, and said lawyers misusing it could face sanctions up to contempt proceedings and police referral.
What to Watch
- The boy's trial in the youth courts, listed for later this week, and whether the fabricated citation features in any argument there.
- The outcome of the CPS internal review and whether it identifies any other affected cases.
- Whether the Bar Council and the Law Society act on the High Court's June 2025 request for urgent steps, and how the tracker of AI-related court errors develops.
Checked
12 claims in this story checked against 1 source: 12 supported.
Show each claim
- SupportedDhillon cited a nonexistent legal case while arguing for prosecuting a child in a High Court dispute.UK news | The Guardian: “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.”
- SupportedThe Guardian understands that the reference came from an AI response generated during an internet search.UK news | The Guardian: “The Guardian understands the reference came from an AI response generated during an internet search.”
- SupportedTwo senior High Court judges called Dhillon’s explanation for relying on the nonexistent case “unsatisfactory”.UK news | The Guardian: “Her explanation for how the nonexistent case came to be relied on has been called “unsatisfactory” by two senior high court judges”
- SupportedBrian Flanagan called the use of the fabricated authority a “serious failure”.UK news | The Guardian: ““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”
- SupportedThe citation Dhillon submitted was CPS – R v J [2024] EWCA Crim 3529.UK news | The Guardian: “submitted a detailed reference to a case she called CPS – R v J [2024] EWCA Crim 3529.”
- SupportedThe child’s lawyers challenged the CPS decision to prosecute, alleging prosecutors had not considered representations from social workers, youth workers and a forensic psychologist.UK news | The Guardian: “They alleged prosecutors had failed to take into account representations from social workers, youth workers and a forensic psychologist.”
- SupportedDhillon made the decision to proceed in April, and the chief crown prosecutor confirmed it.UK news | The Guardian: “The decision to proceed was taken by Dhillon in April and confirmed by the chief crown prosecutor.”
- SupportedIn October, Dhillon admitted the citation was made in error and said she had meant to refer to a real decision made 15 years earlier.UK news | The Guardian: “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.”
- SupportedIn June 2025, the High Court called on the Bar Council and Law Society to consider steps to curb AI hallucinations “as a matter of urgency”.UK news | The Guardian: “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”.”
- SupportedThe CPS said its strict AI policy bars AI from making legal decisions and requires human accuracy checks.UK news | The Guardian: “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”.”
- SupportedA CPS spokesperson said the error was remedied, an internal review was carried out, and learnings included citing case law from trusted legal sources.UK news | The Guardian: ““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.””
- SupportedThe episode brought the UK tracker maintained by Matthew Lee to 101 entries.UK news | The Guardian: “The latest incident brings to 101 the number of entries in a UK tracker maintained by Doughty Street Chambers barrister Matthew Lee”
