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Incident Tracker / United Kingdom

Hancox v Sutherland and others [2026] EAT 139

·Employment Appeal Tribunal·UKWarning

In the UK Employment Appeal Tribunal, an appellant filed a 300-page ChatGPT skeleton argument without checking accuracy or procedural compliance. No reliance was placed on it at the hearing. The tribunal warned that similar filings could be rejected or sanctioned; it allowed one appeal ground to proceed without finding specific fabricated authorities in this document.

Court
Employment Appeal Tribunal
Date
2026-09-17
Who used the AI
Litigant in person
AI tool
ChatGPT
Conduct
A self-represented appellant submitted a 300-page skeleton argument of almost 132,000 words created using ChatGPT, without checking its accuracy or compliance with procedural requirements. He asked opponents to identify inaccuracies by the following afternoon. At the hearing he acknowledged that much of it lacked credibility, and no reliance was placed on it.
Outcome
Warning
Penalty
No monetary penalty recorded
Regulatory outcome
No separate regulatory disposition recorded
Status
Verified against listed sources
Last checked
2026-09-21

What was fabricated or misused

  • A ChatGPT-created skeleton argument of almost 132,000 words across 300 pages, far beyond the 20-page upper limit (paragraphs 82–84)
  • Unverified argument that the appellant acknowledged largely lacked credibility; the judgment does not identify particular fabricated authorities in it (paragraph 85)
  • An attempted transfer of responsibility for identifying inaccuracies to opposing parties, with a deadline the following afternoon (paragraphs 83 and 86)

What the court said

“It was for the Appellant to take responsibility for the contents of his own written argument.”
Employment Appeal Tribunal, paragraph 86
“Compliance with the EAT’s procedural requirements is mandatory, not optional.”
Employment Appeal Tribunal, paragraph 87

Timeline

  1. Appellant filed the 300-page skeleton argument and asked opponents to identify inaccuracies by 4pm on 28 July.
  2. At the preliminary hearing the appellant explained his ChatGPT use; no reliance was placed on the document.
  3. Judgment criticised the unchecked filing and warned of rejection or sanctions in future cases; one appeal ground was permitted to proceed.

Why this case matters

Hancox concerns an unchecked AI-generated filing rather than a judicial finding of specific invented citations. The tribunal identified distinct failures: excessive length, procedural noncompliance, lack of accuracy checks and an attempt to make opponents verify the document at short notice. None required the tribunal to catalogue hallucinated authorities. The ruling also separates criticism of the filing from the merits of the appeal: one ground remained reasonably arguable and was allowed to proceed to a full hearing.

Practice note

Check the tribunal's current practice direction before drafting a skeleton argument, including its length and formatting requirements. Anyone using AI must verify the factual, evidential and legal statements before submission and take responsibility for the resulting document. An opponent's opportunity to respond is not a substitute for that verification. Remove repetitive or irrelevant material rather than submitting an unchecked long-form output because preparation time is short.

Primary sources for this incident

Related regulation records for this incident

No related regulation record has been linked to this incident yet.

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Cite this record

SafeLegalAI Global Legal AI Incident Tracker, “Hancox v Sutherland and others [2026] EAT 139”, safelegalai.com/tracker/hancox-v-sutherland (accessed 2026-09-21). Data: CC BY 4.0.

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