| Decisions in the AI Hallucination Cases database (Damien Charlotin) in which a court addressed established or alleged AI use, accessed 20 September 2026 | 2,044 | Summary Judgment as the Test Case (JLA draft v2.0), Part 1 and note 11: Damien Charlotin, AI Hallucination Cases database, https://www.damiencharlotin.com/hallucinations/ (accessed Sept. 20, 2026). The site displayed a last-updated date of Sept. 19, 2026, without stating that the count corresponds to that date. The compiler states that the database covers decisions in which a court addressed established or alleged AI use in more than a passing reference, excludes mere allegations and the wider universe of fabricated citations, and involves judgment calls on inclusion. |
| Same database: decisions worldwide in which a court or tribunal found that a party relied on hallucinated content, August 2026 | approximately 1,980 | Good Law for What? (LLJ draft), note 2: Damien Charlotin, AI Hallucination Cases (last visited Aug. 28, 2026). "The count is as of August 2026 and is updated periodically." |
| Same database, as described in the smoke-alarm essay (20 September 2026) | passed 1,600 cases | Ross Brodskiy, "The Verification Layer Is a Smoke Alarm, Not a Building Code" (Medium, 20 September 2026): "A researcher at HEC Paris keeps a public database of court decisions involving AI-hallucinated material; it passed 1,600 cases this year and the pace is climbing." |
| Same database: worldwide cases involving AI-fabricated material in legal filings, late 2025 | 486 worldwide, 324 in United States courts | The Promise Fulfilled (JCLLT draft), Part 7: "As of late 2025, Charlotin's database documents 486 worldwide cases involving AI-fabricated material in legal filings, with 324 in United States courts." |
| Fabricated citations in a randomized experiment with upper-level law students (Schwarcz et al., SSRN 5162111) | 18 fabricated citations across 768 graded tasks (127 participants): 3 in the Vincent condition, 4 in the no-AI condition, 11 in the o1-preview condition | Summary Judgment as the Test Case (JLA draft v2.0), Part 6.6 and note 43: Daniel Schwarcz, Sam Manning, Patrick Barry, David R. Cleveland, J.J. Prescott & Beverly Rich, AI-Powered Lawyering, SSRN Working Paper No. 5162111 (posted Mar. 4, 2025), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5162111. Working paper, not peer reviewed as of the date read. "Counts are reported here as counts, not as rates, because the denominators differ by condition and task type." |
| Hallucination on direct verifiable questions about real federal cases, four general-purpose models (Dahl, Magesh, Suzgun & Ho) | at least 58 percent | Summary Judgment as the Test Case (JLA draft v2.0), Part 1 and note 10: Large Legal Fictions, 16 J. Legal Analysis 64 (2024). More than 800,000 queries; abstentions counted as non-hallucinations; the authors characterize their reference-free measures as lower bounds. |
| Incorrect or misgrounded responses from retrieval-grounded commercial legal research tools on an adversarial 202-query set (Magesh et al.) | between 17 and 33 percent | Summary Judgment as the Test Case (JLA draft v2.0), Part 1 and note 9: Hallucination-Free? Assessing the Reliability of Leading AI Legal Research Tools, 22 J. Empirical Legal Stud. 216 (2025). Systems queried Mar. 22 to Apr. 22, 2024, and, for one product, May 23 to 27, 2024; figures describe those product versions. |