Harber v. HMRC
First-tier Tribunal (Tax Chamber) · Dec 4, 2023
- Jurisdiction
- international
- Court
- First-tier Tribunal (Tax Chamber)
- Record ID
- harber-v-hmrc-2023-12-04
- Observed outcome
- No Sanction on Litigant; Warning implied for lawyers.
- Known monetary consequence
- Not recorded
Why this matter warrants attention
Outcome: No Sanction on Litigant; Warning implied for lawyers.. AI UseCatherine Harber, a self-represented taxpayer appealing an HMRC penalty, submitted a document citing nine purported First-Tier Tribunal decisions supporting her position regarding "reasonable excuse". She stated the cases were provided by "a friend in a solicitor's office" and acknowledged they might have been generated by AI. ChatGPT was mentioned as a likely source.Hallucination DetailsThe nine cited FTT decisions (names, dates, summaries provided) were found to be non-existent after checks by the Tribunal and HMRC. While plausible, the fake summaries contained anomalies like American spellings and repeated phrases.…
The Tribunal emphasized that submitting invented judgments was not harmless, citing the waste of public resources (time and money for the Tribunal and HMRC). It explicitly endorsed the concerns raised in the US Mata decision regarding the various harms flowing from fake opinions. While lenient towards the self-represented litigant, the ruling implicitly warned that lawyers would likely face stricter consequences. This was the first reported UK decision finding AI-generated fake cases cited by a litigant
UK tribunals excused the pro-se taxpayer but telegraphed that solicitors filing the same fake cases will be punished.
Failure modes and consequences
- Pro Se
- Trial
- Warning
- None Adjudicated
- AI attribution
- Not Established
- Recorded tool
- Unidentified
- Known monetary consequence
- Not recorded
- Procedural posture
- No Sanction on Litigant; Warning implied for lawyers.
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What this record does—and does not—establish
The current record does not establish a specific AI tool. Do not infer AI use beyond the source.
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Latest evidence review: Source Unavailable (medium confidence).
Controls suggested by the public record
- Read the linked source and subsequent docket history before relying on this record for legal work.