Spanish lawyer facing possible sanctions after court finds 24 fake AI-generated citations in appeal

Judges said the disputed references included non-existent rulings, invented quotations and case numbers linked to unrelated legal matters

Susana Zamora

What began as a dispute over the cause of a worker's lung cancer has resulted in a judicial warning about the risks of using ... artificial intelligence in legal practice after the High Court of Justice of Galicia found 24 false legal citations in an appeal.

The court not only dismissed an appeal filed by a worker who claimed his illness was occupational in origin, but also opened a separate procedure to examine the possible liability of the lawyer who submitted the case.

Judges said the appeal contained non-existent judicial decisions, manipulated quotations and references attributed to courts that had never issued them.

In its ruling, the court stressed that the problem was not the use of artificial intelligence itself, but the failure to verify the information it generated.

Major inaccuracies

The judges reviewed the legal authorities cited in the appeal and found that many of the decisions relied upon were unrelated to the case, while others did not exist at all.

In some instances, case numbers referred to rulings concerning entirely different matters, including dismissals, retirements, mortgage disputes and recruitment processes.

After examining the references, the court concluded that quotations attributed to the Supreme Court and other judicial bodies were fabricated.

"All the texts in quotation marks and the judgments themselves, attributed to the Supreme Court and other courts throughout the appeal, form a coherent and considered discourse, but lie beyond what this Chamber has been able to verify in the Cendoj [official case law database]. They're false," the ruling stated.

Suspicions

The court identified 24 false citations throughout the labour appeal. Some referred to non-existent rulings, while others involved genuine decisions that contained invented passages. Judges also found cases cited in support of their arguments, even though those cases addressed completely unrelated legal issues.

Those findings led the court to suspect the appeal had been drafted using generative artificial intelligence. The ruling described such cases as increasingly common and said that legal documents produced with AI tools may contain fictitious references if they are not properly checked.

The judges said the appeal appeared to correspond to the use of a free generative AI tool without subsequent verification to control the system's repeated "hallucinations", a term used to describe false information presented as factual.

The court referred to a "notorious lack of diligence" and said the lawyer appeared to have relied on AI-generated responses without checking whether the cited rulings actually existed.

While the judges acknowledged that the references could theoretically have been invented deliberately, they said they wished to rule out that possibility at this stage.

"This Chamber wishes to rule out from the outset that the false citations were a conscious invention of the professional," the ruling said.

The court has now opened a separate procedure to determine whether procedural bad faith occurred. Judges said the volume of false citations, non-existent rulings and invented passages suggested a repeated pattern of conduct rather than an isolated mistake.