Rechtbank Amsterdam raises a costs award by €2,315.50 after a fabricated DSM/Fox citation the losing party blamed on AI hallucination

Verification status: CHECKING — handed to the checker, not yet graduated. NOT verified, NOT green. This is a court-origin honest-negative AI-governance record, not a client testimonial. No green badge is sought; the war-room never sets verified.

The problem

A commercial dispute over the sale of a company reached the Rechtbank Amsterdam: the parties had agreed a 2024 purchase price of €2.1 million for all shares with an earn-out of up to €2.35 million, the buyers refused to take the second tranche of shares, and they sought to unwind the deal for mistake or fraud (source). In their statement of defence (conclusie van antwoord) the defendants included what the court described as a completely incorrect quotation from the Hoge Raad’s landmark DSM/Fox contract-interpretation ruling: “in hun conclusie van antwoord een volledig onjuist citaat hebben opgenomen uit het arrest DSM/Fox” (source). The court found those words appear nowhere in that ruling nor anywhere else in published case law: “Deze bewoordingen zijn niet in het genoemde arrest te vinden, en ook niet elders in gepubliceerde rechtspraak.” (source). An independent Dutch specialist newsroom reported the same finding, that a party who “een niet-bestaand citaat uit het bekende arrest DSM/Fox opvoerde, moet daarvoor extra proceskosten betalen” (source). A second, unrelated newsroom, the Amsterdam public broadcaster AT5, reported the same fabricated quotation, that “De aangehaalde zinnen staan echter helemaal niet in een andere uitspraak” (source).

What was built

Nothing was built, and that is the point: this is an adjudicated failure of unverified AI output, not a delivered system. The claimant argued the passage came from a hallucinating AI tool, stating that the defendants had used “artificial intelligence, die is gaan hallucineren” to draft their pleading (source). The defendants’ counsel denied it and could not establish how the passage had entered the document: “De raadsman van [gedaagden] heeft dit ontkend maar heeft niet kunnen achterhalen hoe de passage wel in de conclusie van antwoord terecht is gekomen.” (source). The court declined to make the cause decisive, holding “De rechtbank vindt dit laatste niet beslissend.” (source); the independent newsroom likewise reported that the court “de oorzaak in het midden liet” (source). AT5 reported the same sequence independently, that the opposing party alleged an AI tool “zoals ChatGPT of Gemini” produced the false quotes, that the lawyer denied using AI, and that the judge held “Het AI-gebruik kan volgens de rechter moeilijk bewezen worden, maar hij vindt dat ook niet van belang voor de schadevergoeding” (source). The record therefore names no tool and adjudicates no vendor: what it penalises is the fabricated citation itself.

The outcome

The court called the inclusion of non-existent case law reprehensible because it had needlessly cost both the claimant and the court time: “Het als citaat opnemen van niet bestaande rechtspraak acht de rechtbank kwalijk, want dit heeft zowel [eiser] als de rechtbank nodeloos extra tijd en aandacht gekost.” (source). It set the cost of that at a half point in the costs award: “De rechtbank begroot de daarmee gemoeide kosten op een halve punt in de proceskostenveroordeling (€ 2.315,50).” (source). The independent newsroom reported the same increase, that “De proceskostenveroordeling wordt daarom met 2.315,50 euro verhoogd.” (source). With that half point included, the court set the total costs award against the defendants at ”€ 26.100,85” (source), a figure the newsroom reported as “de totale proceskostenveroordeling 26.100,85 euro” (source), on top of which the buyers were ordered to pay €7,591 in attachment costs and €6,775 in extrajudicial collection costs (source). AT5 independently reported the same figures, that the losing party “moeten ze in totaal 26.100 euro aan proceskosten van de verkoper vergoeden, waarvan dus 2315 euro door het niet bestaande citaat” (source).

Weakest load-bearing source. The strongest evidence is the Tier-1 primary: the published Rechtbank Amsterdam judgment itself, from which every figure and quote above is taken verbatim. It is corroborated by two genuinely independent secondary origins: accountancyvanmorgen.nl (Tier 2, accounting/fiscal trade press; its sibling title fiscaalvanmorgen.nl carries the same editorial and does not count twice) and AT5 (Tier 2, Publieke Omroep Amsterdam, Amsterdam’s public broadcaster, a wholly separate newsroom). The honest limit on the secondaries is precision: AT5 rounds the figures to whole euros (2315, 26.100), so the exact cents (€2,315.50 and €26,100.85) rest on the primary judgment and accountancyvanmorgen.nl, not on AT5. The honest limit on the AI framing is in the ruling itself: the court did not find AI to be the cause. The AI attribution is the claimant’s allegation, the defence denied it, and the court expressly declined to decide it, so this record stands for a fabricated-citation cost sanction, not a proven AI-hallucination finding.

How this was verified. Method: every figure is quoted verbatim from the published judgment of the Rechtbank Amsterdam (ECLI:NL:RBAMS:2026:8258, 12 August 2026 — Tier 1, primary court record), retrieved this session as the data.rechtspraak.nl content XML (46,548 bytes, sha1 df751f3717e7d3c26597fd41879e2c40028e2fa8) and saved to sources/ECLI-NL-RBAMS-2026-8258-primary.xml. Two independent secondaries corroborate the DSM/Fox fabrication finding, the €2,315.50 half-point penalty and the €26,100.85 total: accountancyvanmorgen.nl (Tier 2, accounting/fiscal trade press; archived Wayback 20260824232943) and AT5 (Tier 2, Publieke Omroep Amsterdam, byline Toon Meijerink, 23 Aug 2026; saved to sources/at5-2026-08-23.html, Wayback capture requested this session). AT5 reports the figures rounded to whole euros. Archive flag: web.archive.org/save returned HTTP 500 for the rechtspraak deeplink and content URL this session, so the primary’s own Wayback snapshot is pending a retry; the local byte-tied XML is the retained primary evidence in the meantime. Verified 2026-08-24 (checking round).

Sources

1. Rechtbank Amsterdam · Vonnis ECLI:NL:RBAMS:2026:8258 · 12 August 2026 · https://uitspraken.rechtspraak.nl/details?id=ECLI:NL:RBAMS:2026:8258 — Tier 1 (primary published court judgment; retrieved as data.rechtspraak.nl content XML, byte-tied locally, sha1 df751f3717e7d3c26597fd41879e2c40028e2fa8; Wayback snapshot pending retry).
2. Accountancy Vanmorgen · Rechtbank verhoogt veroordeling in proceskosten na gebruik niet-bestaand citaat: “kwalijk” · 21 August 2026 · https://www.accountancyvanmorgen.nl/2026/08/21/rechtbank-verhoogt-veroordeling-in-proceskosten-na-gebruik-niet-bestaand-citaat-kwalijk/ — Tier 2 (independent Dutch specialist newsroom, accounting/fiscal trade press; reproduces the DSM/Fox fabrication finding, the €2,315.50 increase and the €26,100.85 total; archived Wayback 20260824232943).
3. AT5 · Advocaat gebruikt nepcitaat, mogelijk door AI, en moet ruim 2300 euro betalen · 23 August 2026 · https://www.at5.nl/artikelen/239607/advocaat-gebruikt-nepcitaat-mogelijk-door-ai-en-moet-ruim-2300-euro-betalen — Tier 2 (Publieke Omroep Amsterdam, Amsterdam’s public broadcaster; a second, unrelated newsroom independently reporting the fabricated DSM/Fox citation, the court’s “kwalijk” finding, the 2315-euro penalty and 26.100-euro total rounded to whole euros, and the AI attribution with cause left undecided; byline Toon Meijerink; saved locally to sources/at5-2026-08-23.html, Wayback capture requested this session).

Related case files

• The Raad van Discipline ‘s-Hertogenbosch reprimanded a Dutch lawyer and ordered €1,250 costs over AI-fabricated ECLI citations — the same fabricated-citation failure mode in the Netherlands, but via the bar-discipline route rather than a civil costs order.
• A.P. v. S.K., where the Quebec Court of Appeal ordered $1,000 costs over ChatGPT-fabricated case law — another court using its costs power, not a fine, to sanction invented authorities.
• Tribunale di Siracusa imposed €30,206 for AI-fabricated citations as lite temeraria — a civil court reaching a far larger money figure for the same conduct, useful for gauging how European courts price fabricated case law.