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Zzaman v. HMRC

Court
First-tier Tribunal (Tax Chamber)
Jurisdiction
UK
Decided
2025-04-03
AI tool
Implied
Outcome
Warning
Monetary penalty
None reported

What was hallucinated

Fabricated: Case Law | Verify the existence of the case or cite correctly if it exists. || Misrepresented: Case Law | Unilever Italia (ECJ, C-443/98) was invoked as relevant to retrospective tax fairness; the Tribunal found it concerned national technical regulations and was irrelevant. || Misrepresented: Case Law | R v R was cited to support arguments on retrospective legislation and the rule of law; the Tribunal held it was of tangential relevance at best. || Misrepresented: Case Law | Bhatt Murphy was cited on legitimate expectation to support the appeal; the Tribunal held it was not relevant and, in any event, outside its jurisdiction. || Misrepresented: Case Law | National & Provincial Building Society v UK was cited to argue retrospective tax legislation was unlawful; the Tribunal noted the case actually found such legislation lawful. || Misrepresented: Case Law | Garnmoss was relied upon to suggest HMRC had a general duty to notify HICBC liabilities; the Tribunal held it addressed VAT surcharge notification and did not establish such a duty. || Misrepresented: Case Law | Hok was cited to support a general HMRC duty to notify HICBC liabilities; the Tribunal held it concerned notification of default and did not create a general duty. || Misrepresented: Legal Norm | Appellant asserted that his 11 June 2021 phone calls amounted to an appeal notice for s97 FA 2022 purposes; the Tribunal held an appeal must be in writing (s31A TMA) and the calls pre-dated any assessment. || Fabricated: Case Law | Verify the existence of the case or cite correctly if it exists. || Misrepresented: Case Law | James Robertson v HMRC was cited in support of general unfairness arguments; the Tribunal found it not relevant to the issues. || Misrepresented: Legal Norm | Appellant asserted a general legal duty on HMRC to inform taxpayers of HICBC liability; the Tribunal found no authority and stated no such duty exists under the self-assessment regime.

Details

Plaintiff had disclosed the use of AI in preparing his statement of case. The court noted:"29. However, our conclusion was that Mr Zzaman’s statement of case, written with the assistance of AI, did not provide grounds for allowing his appeal. Although some of the case citations in Mr Zzaman’s statement were inaccurate, the use of AI did not appear to have led to the citing of fictitious cases (in contrast to what had happened in Felicity Harber v HMRC [2023] UKFTT 1007 (TC)). But our conclusion was that the cases cited did not provide authority for the propositions that were advanced. This highlights the dangers of reliance on AI tools without human checks to confirm that assertions the tool is generating are accurate.Litigants using AI tools for legal research would be well advised to check carefully what it produces and any authorities that are referenced. These tools may not have access to the authorities required to produce an accurate answer, may not fully “understand” what is being asked or may miss relevant materials. When this happens, AI tools may produce an answer that seems plausible, but which is not accurate. These tools may create fake authorities (as seemed to be the case in Harber) or use the names of cases to which it does have access but which are not relevant to the answer being sought (as was the case in this appeal).There is no reliable way to stop this, but the dangers can be reduced by the use of clear prompts, asking the tool to cite specific paragraphs of authorities (so that it is easy to check if the paragraphs support the argument advanced), checking to see the tool has access to live internet data, asking the tool not to provide an answer if it is not sure and asking the tool for information on the shortcomings of the case being advanced. Otherwise there is a significant danger that the use of an AI tool may lead to material being put before the court that serves no one well, since it raises the expectations of litigants and wastes the court’s time and that of opposing parties."

Sanction teardown · First-tier Tribunal (Tax Chamber), UK · 2025-04-03

Zzaman v. HMRC

What happened

In First-tier Tribunal (Tax Chamber), UK, a filing relied on an unnamed/unconfirmed AI tool to help draft legal argument. The court identified the following problems with the citations in that filing:

  • Fabricated (Case Law)
    Verify the existence of the case or cite correctly if it exists.
  • Misrepresented (Case Law)
    Unilever Italia (ECJ, C-443/98) was invoked as relevant to retrospective tax fairness; the Tribunal found it concerned national technical regulations and was irrelevant.
  • Misrepresented (Case Law)
    R v R was cited to support arguments on retrospective legislation and the rule of law; the Tribunal held it was of tangential relevance at best.
  • Misrepresented (Case Law)
    Bhatt Murphy was cited on legitimate expectation to support the appeal; the Tribunal held it was not relevant and, in any event, outside its jurisdiction.
  • Misrepresented (Case Law)
    National & Provincial Building Society v UK was cited to argue retrospective tax legislation was unlawful; the Tribunal noted the case actually found such legislation lawful.
  • Misrepresented (Case Law)
    Garnmoss was relied upon to suggest HMRC had a general duty to notify HICBC liabilities; the Tribunal held it addressed VAT surcharge notification and did not establish such a duty.
  • Misrepresented (Case Law)
    Hok was cited to support a general HMRC duty to notify HICBC liabilities; the Tribunal held it concerned notification of default and did not create a general duty.
  • Misrepresented (Legal Norm)
    Appellant asserted that his 11 June 2021 phone calls amounted to an appeal notice for s97 FA 2022 purposes; the Tribunal held an appeal must be in writing (s31A TMA) and the calls pre-dated any assessment.
  • Fabricated (Case Law)
    Verify the existence of the case or cite correctly if it exists.
  • Misrepresented (Case Law)
    James Robertson v HMRC was cited in support of general unfairness arguments; the Tribunal found it not relevant to the issues.
  • Misrepresented (Legal Norm)
    Appellant asserted a general legal duty on HMRC to inform taxpayers of HICBC liability; the Tribunal found no authority and stated no such duty exists under the self-assessment regime.

Which AI tool

an unnamed/unconfirmed AI tool. Note: Charlotin's public database records tool attribution only where a court order, brief, or reporting on the matter states it explicitly; "unidentified" or "implied" means the record indicates AI use but does not name a specific product — we do not guess.

Outcome

Warning

Additional detail

Plaintiff had disclosed the use of AI in preparing his statement of case. The court noted:"29. However, our conclusion was that Mr Zzaman’s statement of case, written with the assistance of AI, did not provide grounds for allowing his appeal. Although some of the case citations in Mr Zzaman’s statement were inaccurate, the use of AI did not appear to have led to the citing of fictitious cases (in contrast to what had happened in Felicity Harber v HMRC [2023] UKFTT 1007 (TC)). But our conclusion was that the cases cited did not provide authority for the propositions that were advanced. This highlights the dangers of reliance on AI tools without human checks to confirm that assertions the tool is generating are accurate.Litigants using AI tools for legal research would be well advised to check carefully what it produces and any authorities that are referenced. These tools may not have access to the authorities required to produce an accurate answer, may not fully “understand” what is being asked or may miss relevant materials. When this happens, AI tools may produce an answer that seems plausible, but which is not accurate. These tools may create fake authorities (as seemed to be the case in Harber) or use the names of cases to which it does have access but which are not relevant to the answer being sought (as was the case in this appeal).There is no reliable way to stop this, but the dangers can be reduced by the use of clear prompts, asking the tool to cite specific paragraphs of authorities (so that it is easy to check if the paragraphs support the argument advanced), checking to see the tool has access to live internet data, asking the tool not to provide an answer if it is not sure and asking the tool for information on the shortcomings of the case being advanced. Otherwise there is a significant danger that the use of an AI tool may lead to material being put before the court that serves no one well, since it raises the expectations of litigants and wastes the court’s time and that of opposing parties."

How Citation Safe would have caught this

Citation Safe runs three deterministic layers before a brief is filed: (1) does the citation exist against CourtListener's database of published opinions, (2) if quoted, does that exact language appear in the source, (3) does the cited case actually support the proposition it is cited for. Fabricated case citations fail Layer 1. Fabricated or misattributed quotations fail Layer 2 even when the underlying case is real. Misrepresented holdings — a real case cited for a proposition it does not support — are the target of Layer 3. None of these checks involve asking another language model whether the citation looks right; they are lookups and text-matches against the actual source, which is why a hallucinated citation has to survive a direct lookup against the authoritative source — not another model's opinion — to earn a VERIFIED stamp; our measured false-verify rate is published live at /quality.

Check a brief before you file it → · See our live false-verify rate

Source: https://www.damiencharlotin.com/documents/452/Zzaman_v._HMRC_UK_April_3_2025.pdf, via Damien Charlotin's public AI Hallucination Cases Database (CC0).

Source: https://www.damiencharlotin.com/documents/452/Zzaman_v._HMRC_UK_April_3_2025.pdf

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