What was hallucinated

Fabricated: Case Law | Plaintiff cited a nonexistent CFC case to support unjust enrichment jurisdiction; the citation leads to a different case in the reporter. || Fabricated: Case Law | Plaintiff cited a nonexistent case to argue CFC jurisdiction; the reporter citation points to a different case and subject, and neither Defendant nor the Court could locate any such case. || Fabricated: Case Law | Plaintiff relied on a case that does not exist in the Federal Claims reporter to assert jurisdiction over unjust enrichment. || Fabricated: Case Law | Plaintiff cited a nonexistent case to claim CFC jurisdiction over unjust enrichment; the reporter citation corresponds to a different case. || Misrepresented: Case Law | Plaintiff mischaracterized Hunt Building as acknowledging unjust enrichment claims in government contracts; the actual case is a bid protest with no mention of unjust enrichment. || Misrepresented: Legal Norm | Plaintiff asserted that restitution is a standalone money-mandating source conferring CFC jurisdiction over unjust enrichment; the Court held restitution is not independently money-mandating and such claims lie outside CFC jurisdiction absent a separate money-mandating provision.

Details

AI UseThe plaintiff did not admit to using AI, but the court inferred likely use due to the submission of fabricated citations matching the structure and behavior typical of generative AI hallucinations. The decision referenced public concerns about AI misuse and cited specific examples of federal cases where similar misconduct occurred.Hallucination DetailsPlaintiff cited:Tucker v. United States, 24 Cl. Ct. 536 (1991) – does not existFargo v. United States, 184 F.3d 1096 (Fed. Cir. 1999) – fabricated citation pointing to an unrelated Ninth Circuit caseBristol Bay Native Corporation v. United States, 87 Fed. Cl. 122 (2009) – fictionalQuantum Construction, Inc. v. United States, 54 Fed. Cl. 432 (2002) – nonexistentHunt Building Co., LLC v. United States, 61 Fed. Cl. 243 (2004) – real case misused; contains no mention of unjust enrichmentRuling/SanctionThe court granted the government’s motion to dismiss for lack of subject matter jurisdiction under Rule 12(b)(1). Although the court found a clear Rule 11 violation, it opted not to sanction the plaintiff, citing the evolving context of AI use and the absence of bad faith. A formal warning was issued, with notice that future hallucinated filings may trigger sanctions.Key Judicial ReasoningJudge Roumel noted that plaintiff’s attempt to rely on fictional case law was a misuse of judicial resources and a disservice to her own advocacy. The court cited multiple precedents addressing hallucinated citations and AI misuse, stating clearly that while leeway is granted to pro se litigants, the line is crossed when filings rely on fictitious law.

Sanction teardown · Fed. claims court, USA · 2025-03-31

Sanders v. USA

What happened

In Fed. claims court, USA, 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)

Plaintiff cited a nonexistent CFC case to support unjust enrichment jurisdiction; the citation leads to a different case in the reporter.
Fabricated (Case Law)

Plaintiff cited a nonexistent case to argue CFC jurisdiction; the reporter citation points to a different case and subject, and neither Defendant nor the Court could locate any such case.
Fabricated (Case Law)

Plaintiff relied on a case that does not exist in the Federal Claims reporter to assert jurisdiction over unjust enrichment.
Fabricated (Case Law)

Plaintiff cited a nonexistent case to claim CFC jurisdiction over unjust enrichment; the reporter citation corresponds to a different case.
Misrepresented (Case Law)

Plaintiff mischaracterized Hunt Building as acknowledging unjust enrichment claims in government contracts; the actual case is a bid protest with no mention of unjust enrichment.
Misrepresented (Legal Norm)

Plaintiff asserted that restitution is a standalone money-mandating source conferring CFC jurisdiction over unjust enrichment; the Court held restitution is not independently money-mandating and such claims lie outside CFC jurisdiction absent a separate money-mandating provision.

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

AI UseThe plaintiff did not admit to using AI, but the court inferred likely use due to the submission of fabricated citations matching the structure and behavior typical of generative AI hallucinations. The decision referenced public concerns about AI misuse and cited specific examples of federal cases where similar misconduct occurred.Hallucination DetailsPlaintiff cited:Tucker v. United States, 24 Cl. Ct. 536 (1991) – does not existFargo v. United States, 184 F.3d 1096 (Fed. Cir. 1999) – fabricated citation pointing to an unrelated Ninth Circuit caseBristol Bay Native Corporation v. United States, 87 Fed. Cl. 122 (2009) – fictionalQuantum Construction, Inc. v. United States, 54 Fed. Cl. 432 (2002) – nonexistentHunt Building Co., LLC v. United States, 61 Fed. Cl. 243 (2004) – real case misused; contains no mention of unjust enrichmentRuling/SanctionThe court granted the government’s motion to dismiss for lack of subject matter jurisdiction under Rule 12(b)(1). Although the court found a clear Rule 11 violation, it opted not to sanction the plaintiff, citing the evolving context of AI use and the absence of bad faith. A formal warning was issued, with notice that future hallucinated filings may trigger sanctions.Key Judicial ReasoningJudge Roumel noted that plaintiff’s attempt to rely on fictional case law was a misuse of judicial resources and a disservice to her own advocacy. The court cited multiple precedents addressing hallucinated citations and AI misuse, stating clearly that while leeway is granted to pro se litigants, the line is crossed when filings rely on fictitious law.

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/356/Sanders_v._USA_USA_March_31_2025.pdf, via Damien Charlotin's public AI Hallucination Cases Database (CC0).