CPS: Full internal review
The Crown Prosecution Service (CPS) put hallucinated cases produced by artificial intelligence (AI) before the High Court in an extradition appeal, it has admitted.
But it told Mr Justice Sweeting that “while the immediate source of the error may have been the use of generative artificial intelligence, the operative cause was human error in the failure to verify the authorities relied upon in formal submissions placed before the court”.
The judge said: “The CPS emphasised that this was not a deliberate attempt to mislead, but rather an isolated incident arising from inadequate checking of written work.”
The errors came to light before the hearing of the two appeals against extradition orders – which were ultimately rejected – and “therefore had no impact on argument or the court’s judgment”, said Sweeting J.
“I have accepted the apology given on behalf of the Crown Prosecution Service and the assurance that there was no attempt to mislead.
“I have noted the steps taken to ensure that there is no repetition but considered that it was necessary to set out what had taken place in this judgment given the serious consequences that an error of this nature might have had in other circumstances.
“It would be naive to assume that there will not be an increasing use of artificial intelligence in legal work in future; indeed, that may be both necessary and beneficial. The episode highlights the risks of its use without appropriate oversight particularly for legal research.”
There was no indication in the ruling that the judge applied the guidance set out in Ayinde last year to decide whether further action was required.
The two non-existent authorities were cited in the grounds of opposition prepared last year by the CPS, errors that were carried forward in a document headed ‘Respondent submissions’ prepared by junior counsel.
They were not identified at the permission stage, even though there were before the court at that point, but were not relied upon in the skeleton argument prepared by senior and junior counsel in February this year.
The skeleton did not explain that the false citations had by then been identified.
Junior counsel had raised questions about them internally, shortly before the appellants did too.
A Chief Crown Prosecutor told the court that the CPS had carried out “a full internal review” to establish how the error occurred, while senior managers reviewed 78 cases conducted by the same lawyer. “That review did not identify similar issues, and the lawyer’s work was otherwise assessed to be of a good standard.”
Sweeting J went on: “Thirdly, the CPS used the incident as an opportunity to reinforce professional obligations within the Extradition Unit. In particular, lawyers were reminded of their duty, as officers of the court, to ensure the accuracy of written submissions.
“Internal processes were also reviewed, and the learning points arising from the incident were disseminated more widely across the organisation.”
In a commentary on the case, barrister Matthew Lee – who has been charting cases of AI hallucinations in the courts – said the case showed how they could cascade.
“The error was not caught immediately. The false authorities appear to have moved from the CPS’s grounds of opposition into a further document, with the result that non-existent cases were likely before the court in more than one place. They then survived the permission stage.
“That matters because it shows how easily hallucinated material can pass from one document to another and how quickly an initial error can become embedded in the litigation process.
“Once that happens, the risk is not only that the court is misled, but that later readers may assume the material has already been checked simply because it has appeared more than once.”
He added that the case was notable because “when the state puts non-existent case law before a court in proceedings touching the liberty of the subject, the consequences of relying on hallucinated content without careful checking are significant”.
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